The Steam Turbine and Other Inventions of Sir Charles Parsons, O.M. by R H Parsons (1942)


Reprinted by David Steinberg with permission of copyright holders the British Council.































Since the amenities of civilised life depend almost entirely on the availability of power for industrial purposes, those pioneers who have provided mankind with the means of obtaining power more cheaply and abundantly will always rank high among the benefactors of humanity. From this point of view no man has made a greater contribution to human welfare than Sir Charles Parsons by the revolutionary improvements he brought about in the use of steam. His name will always be particularly associated in the minds of the public with the invention of the steam turbine and its application to duties on land and sea, although, as will be seen, his contribution to the advance of science and engineering extended far beyond the limits of a single invention. Even if Parsons had done nothing more than produce the first practical steam turbine his fame as an engineer would have been secure for all time. By its introduction he exercised an influence upon industry that was comparable only with that of Watt about a century earlier, though vastly more far-reaching in its effects by reason of the wider field open to him.

When Watt built his first condensing steam engines, the operation of pumping machinery for mines was almost the only duty for which engines were required. Towards the end of the eighteenth century steam engines began to take the place of water wheels as prime movers for mills and factories, but as the dynamo had not then been invented, the generation of electricity and all the industrial development that depends on it lay still in the future. Nor was there at the time, except perhaps in the minds of a few enthusiasts, any idea that steam would ever be used for the propulsion of ships. There is no evidence that Watt foresaw the immense field there would be for steam power in marine work, even though his firm of Boulton and Watt constructed the engine that drove Fulton's historic little steam vessel the Clermontin 1806. Parsons, on the other hand, commenced his life's work when the two great branches of electrical and marine engineering were already established, each of them offering an unbounded scope for the steam turbine as soon as its practicability could be demonstrated. In another respect also the times were auspicious for him. The reciprocating steam engine, which had held the field unchallenged for a hundred years, had practically reached the limit of its development. The labours of generations of engineers had raised it to a very high degree of excellence, and no further refinement of design was capable of effecting any substantial increase in its efficiency. Furthermore, the powers for which reciprocating engines could be built were restricted by considerations of size and weight to units of a few thousand horse-power only, so that if any further advance was to be made in steam engineering it could only take place along some totally different lines. It is as true in engineering as in every other kind of evolutionary activity, that approach to perfection in any direction is equally the approach to stagnation, so that if progress is to continue some radical departure has to be made.




Parsons, alone among his contemporaries, saw in the turbine principle the means of escape from the limitations of the reciprocating engine, or perhaps it would be more accurate to say that he alone possessed the genius and courage to transform a possibility into a reality. That he foresaw from the outset the wide diversity of the duties to which the turbine could be applied is clear from his earliest patents, which also showed a remarkable understanding of the conditions essential to success in meeting the requirements of each particular case. Problem after problem was solved in the most admirable way, and. instead of being merely an ingenious toy, as many people at first considered it, the turbine steadily and surely won recognition as the standard type of prime mover wherever the production of steam power was concerned. It can be constructed for far larger outputs than any reciprocating engine, and it is moreover much more economical of steam. Indeed, apart from the benefits that the work of Parsons has conferred upon the present generation, the economy which he made possible in the consumption of the exhaustible fuel resources of the world entitles him to the gratitude of posterity.

For those who are not acquainted with the principle of the steam turbine, it may be well to explain briefly the nature of the great invention of Parsons. The object that he set himself was that of producing power by utilising the velocity of a jet of steam, instead of using the pressure of the steam to drive a piston as in the ordinary reciprocating engine. It was evident that a jet of steam could be made to turn a wheel by acting on blades set around its circumference, or alternatively it could be used to develop power by its own reaction when escaping tangentially from an orifice in a rotating wheel or arm. Both devices had already been suggested by innumerable inventors, but the hitherto insuperable difficulty in constructing a practical turbine by either method lay in utilising the excessive velocity of the steam. Even steam at a comparatively low pressure escaping into the atmosphere may easily be travelling at more than 2500 feet per second, or over I700 miles an hour, while twice this velocity may be attained by high-pressure steam flowing into a good vacuum. To make use of such velocities effectively in a simple turbine, the blades or other moving elements would have to travel at about half the speed of the steam, for otherwise an undue proportion of the energy of the jet would be uselessly carried away in the steam leaving the wheel. The blade speeds required for efficiency would therefore be so high that they would be prohibited by reason of centrifugal force alone, apart from other considerations. That Watt, with his sound engineering instinct, had appreciated this fact’ is shown by one of his letters to Boulton. His partner had expressed fears as to the effect that the competition of a proposed steam turbine might have on their engine-building business, but Watt had disposed of them with the remark that ' Without God makes it possible for things to move 1000 feet per second, it cannot do much harm'.

Although there are to-day large turbines containing blades whose tips travel at speeds even greater than Watt thought would be possible only by a special dispensation of Providence, such speeds were out of the question under the conditions existing when Parsons commenced his work. He could therefore only secure a proper relationship between steam speed and blade speed by reducing the former to a manageable amount. Now the speed of a jet of steam will obviously depend upon the difference of pressure that causes the flow. It occurred to Parsons that he could attain his end by the device of causing the whole expansion of the steam to take place by a series of steps, each partial drop of pressure being only sufficient to generate a velocity that could be efficiently utilised by blades running at a moderate speed. To put this idea into effect he constructed a turbine consisting of a cylindrical rotor enclosed in a casing. The steam flowed along the annulus between the two, parallel to the axis of the machine, and in so doing it had to pass through rings of blades fixed alternately in the casing and rotor. The passages between the blades of each ring formed virtually a set of nozzles in which a partial expansion of the steam could take place. In passing through each ring of fixed blades the steam acquired a certain velocity due to this expansion, and the jets so formed gave up their energy in driving the succeeding row of moving blades. The passages between the latter blades also acted as nozzles, permitting a further partial expansion, so that the moving blades were impelled partly by the 'action' of the steam entering them and partly by the 'reaction' of the steam leaving them.

The principle of subdividing the whole expansion of the steam into a number of stages, so that only comparatively moderate velocities have to be dealt with, still forms the basis of all efficient turbine design. The secondary principle of utilising the 'reaction' of the steam expanding in moving blades has remained typical of the Parsons turbine. It is not, however, an indispensable characteristic of an efficient turbine, and certain inventors subsequent to Parsons, notably C. G. Curtis in the United States and Professor A. Rateau in France, preferred for constructional reasons to confine the expansion of the steam to fixed nozzles. Machines of the latter type, in which the steam drives the blading of each stage by virtue of its velocity only, are known as 'impulse' turbines. Although they have attained an honourable position in the industry, it is generally recognized that the 'reaction' principle, chosen by Parsons for his original turbine, is conducive to the highest efficiency, so that large machines which are nominally of the impulse type are now often designed to work with a certain amount of reaction in their blading.

In addition to laying down the broad lines necessary to success in the development of the new kind of prime mover, Parsons had many practical problems to solve before his ideas could be embodied in an actual machine. Not only had a suitable form of blading to be invented and appropriate manufacturing methods devised, but the design generally had to conform to conditions quite outside the range of ordinary engineering practice. For example, to obtain the desired blade velocity in the small turbine he first constructed a rotational speed of no ,000 revolutions per minute had to be adopted. This was over fifty times as fast as the fastest reciprocating engine of the day, and It involved the invention of a new kind of bearing which would permit of a long rotor, inevitably out of mathematically perfect balance, running at such a speed without vibration. Means had also to be provided for the continuous lubrication of these bearings, and a totally new method of controlling the speed of the machine had to be devised. Again, it was realised that the flow of the steam would result in an end-thrust on the blading, and to prevent this being transmitted to the bearings, where it might have caused trouble, Parsons neutralised it by the ingenious expedient of admitting the steam midway along the rotor and causing it to flow equally towards each end. His subsequent invention of 'dummy pistons' rendered the double flow principle unnecessary for machines of moderate output, but without it the large and efficient high-speed machines of to-day could hardly be built. A study of Parsons' first turbine patent, taken out in 1884, will show how clearly he appreciated the difficulties in his path and how thoroughly he had considered the means of overcoming them. Again, obvious as the principle of expanding the steam by stages now appears to us, the invention must be regarded in the light of the state of the art at the time. The only previous attempts to develop any useful amount of power from steam, otherwise than by causing it to drive a piston, had taken the form of machines driven by the reaction of jets issuing from the ends of rotating arms, on the lines of the classical Aeropile of Hero of Alexandria. The famous Cornish engineer, Richard Trevithick, had constructed what he called a ''whirling engine' on this principle in 1815, and other more or less workable machines of the same kind had been made from time to time, but the lessons to be drawn from them were rather of warning than encouragement. It is true that various inventors had propounded plans for the more rational utilisation of steam in machines of the turbine type, but no such machines had assumed a practical form and steam engineers in general believed that any attempt to supersede the reciprocating engine as a prime mover was foredoomed to failure. The success of Parsons' first little turbine marked the beginning of the most revolutionary change in the history of steam engineering. By developing power from the velocity of steam rather than from its static pressure, the turbine was exempt from the mechanical limitations of the reciprocating engine. Its invention has enabled the power that could be produced by a given weight and size of machinery to be multiplied a hundredfold and it has provided that purely rotational motion at high speed so desirable for the driving of electrical generators and many other classes of machinery. In addition to these advantages, it has brought about a remarkable economy in the use of steam.




The most obvious field for such a high-speed prime mover as the turbine was in the driving of electric generators, and it was for this purpose that it was originally designed. The dynamos of those days were small machines driven usually at 1000 to 1500 revolutions per minute by a belt from the flywheel of a reciprocating engine. Parsons required a dynamo that could be driven directly by his turbine at a speed of 18,000 revolutions per minute, in order that the combination should constitute a small, simple and self-contained generating unit. None of the established dynamo makers would have considered for a moment the construction of a machine so completely outside the range of previous experience. It must be remembered that at the time electrical engineering was in a very elementary condition and dependent mainly upon empirical knowledge, for two years had still to elapse before Hopkinson propounded the theory of the magnetic circuit and laid down the fundamental principles of the design of electrical machinery. Parsons faced the question with the same boldness that he showed in the design of his turbine and he achieved an equally striking success. Both electrical and mechanical problems had to be solved, for the alternations of magnetism in the core were vastly more rapid than in any machine yet built, while the mechanical stresses to be provided against will be realised from the fact that a centrifugal force of 5.5 tons was developed by every pound of metal at the surface of the armature. The dynamo was of the bi-polar type with an output of 75 amperes at 100 volts. Both turbine and dynamo fulfilled the anticipations of their designer, and after many years of useful work this historic unit was presented to the Science Museum at South Kensington, where it is carefully preserved for the instruction of future generations.

It required much persistence on the part of Parsons before his turbo-generators were able to enter their proper field of central station work. By 1888, although about two hundred of them were in service, they were employed almost exclusively for ship-lighting duties, and no electric light company had yet taken any notice of them. Parsons therefore decided that he would, himself, have to effect the introduction of the turbine into the industry that it was destined to dominate; so, aided by friends, he founded the Newcastle and District Electric Lighting Co., which began operations in January 1890 with a station at Forth Banks equipped with a pair of 75 kw. turbo-alternators. But even this demonstration of its suitability for power-station service failed to arouse any general interest, and Parsons had to accept a financial risk in the businesses of companies formed to supply electricity to Cambridge in 1892 and to Scarborough in 1893 in order to give them sufficient confidence to install turbine machinery.

Progress thenceforward was rapid. The success of the turbine in saving the chief London station of the Metropolitan Electric Supply Co. from being shut down altogether in 1894 on account of the nuisance caused by its reciprocating engines attracted general attention and definitely established its footing in the industry. Larger and larger units were continually called for, and with every increase in size the advantages of the turbine became more apparent. Parsons' earlier machines had been constructed at the works of Messrs Clarke, Chapman and Co., in which firm he was a partner, but in 1889 he founded the present firm of Messrs C. A. Parsons and Co., Ltd., at Heaton, near Newcastle, in order to have complete control over their manufacture. Parsons would have attained high fame for his electrical work alone had not this been- overshadowed in the minds of the public by the spectacular developments of his steam turbine. By 1900 he was building generating sets of 1000 kw. capacity, while in 1912 he undertook to build a turbo-alternator with an output of 25,000 kw., by far the largest and most efficient generating unit in the world at the time. This machine was installed in the Fisk Street Power Station of the City of Chicago, and it proved so successful that in 1923 Parsons was entrusted with the contract for a unit of 50,000 kw. for the same city. He lived to see an output of more than 200,000 kw. delivered by a single turbo-generator, and the reciprocating steam engine completely superseded by the turbine for central station work.

The growth of electricity supply consequent upon the invention of the turbine created a demand, not only for larger generating units, but also for higher transmission voltages in order that more extensive areas might be economically served. In the early days the practice had been to generate at about 2000 volts, and to step up this pressure when required by means of transformers. Ferranti had given a lead in the direction of higher generating voltages in 1889 by designing large slow-speed alternators to generate single-phase current at 10,000 volts for his famous Deptford Station. These machines were, however, recognised as exceptional and they had little or no influence on the industry generally. The first real advance towards modern conditions was made by Parsons in 1905 when he supplied a pair of 1500 kw. turbo-alternators generating at 11,000 volts to the Frindsbury Power Station in Kent. Once it had been demonstrated that high-speed alternators could be safely constructed for this voltage, it soon became a usual generating pressure and remained so for many years. As before, when higher pressures were required for transmission they were obtained by the use of transformers, which were commonly attached permanently to the machines they served. There was, however, to Parsons' mind, something illogical in generating at 11,000 volts or thereabouts when the whole current might have to leave the station at a higher voltage. He therefore attacked the problem with his usual energy and insight, with the result that in 1928 he produced a 25,000 kw. Turbo-alternator designed to generate directly at 36,000 volts. This was installed in the Brimsdown Power Station the same year. The windings of the machine were constructed in accordance with an entirely new principle, which made it possible to generate at 36,000 volts without submitting the insulation of the windings to any greater electrical stress than is usual in an ordinary 11,000 -volt generator. The machine was entirely successful and once more Parsons had set a new standard in power-station machinery. Many of the most important power stations, both in Great Britain and abroad, have now adopted the practice of generating directly at 36,000 volts, thereby eliminating the large and costly step-up transformers necessary with the previous method.

Enough has been said to indicate, in some small measure, how much the electrical industry owes to Parsons. He not only provided it with the turbo-generator, but led the way for more than a generation in every important development of power-station machinery. Excepting the introduction of the cylindrical form of rotor for turbo-alternators by the late C. E. L. Brown, who was building turbine machinery on the Continent under Parsons' patents, it may fairly be said that there was no notable improvement in the design of high-speed electrical machines that did not originate in the Heaton Works. Moreover, whenever a larger type of machine was called for, Parsons was ready to construct it, even if far beyond the capacity of anything previously built, provided only he was satisfied that the requirements could be successfully fulfilled. His enterprise was never restrained by considerations of what had been done, but only by what could be safely accomplished with the materials of the day. Typical of his engineering courage was the jump from 350 to 1000 kw. in 1900, and the still more spectacular leap from 6000 to 25,000 kw. in 1912. He was an equally great pioneer in all matters pertaining to efficiency. As long ago as 1900 he made the first practical experiments with regard to the reheating of steam in the course of its expansion, and later proved the benefits of this procedure in the important power stations of North Tees, Barking, and Dunston, the last of which held for a time the record of efficiency for all British stations. It was Parsons also who introduced the now universal practice of extracting air from a condenser by means of a steam-jet, his ‘Vacuum Augmentor' of 1902 being the direct prototype of the modern steam-jet air-ejector, without which the present efficiency of condensing plants would be impossible.

Parsons, again, was the first engineer to take practical advantage of the possibility of effecting an improvement of the thermodynamic cycle of a steam turbine plant by the regenerative heating of the feed water, a development for which he acknowledged his indebtedness to the original proposal of Mr James Weir in 1876. He applied this principle in the Blaydon Burn Power Station in 1916 by heating the feed water progressively by means of partially expanded steam extracted from the turbine at different pressures, a procedure which has since been adopted as an indispensable feature of every efficient steam power plant in the world. The result of these advances, coupled with innumerable other improvements due to his prolific brain, enabled him to construct generating units capable of operating with a heat consumption of no more than 9280 B.T.U.per kw. hour, a figure that even to-day could hardly be surpassed by the largest and most efficient machines in existence.

Although the technical merits of Parsons' work in the development of turbines and electrical generators can only be fully appreciated by experts, the benefits that have accrued from it are obvious to all. It is sufficient to contemplate the part played by electricity in our domestic and industrial well-being to realise how greatly we are dependent upon a cheap and abundant supply. This has come to be regarded as one of the necessities of civilised life, and it is very certain that the service we now enjoy would have been utterly impossible without the turbo-generator. The cheapness of electricity produced by a steam power station depends mainly upon three factors, namely the quantity of fuel required to generate it, the capital charges on the station and equipment, and the expenses of running and maintaining the plant. On all of these the influence of turbine machinery has been profound. A modern station can be operated with a fraction of the fuel that would have been necessary for the same output in the days of the reciprocating engine, chiefly because the turbine can take advantage of a far greater range of expansion of the steam. The capital and labour charges are less because of the larger sizes of individual turbine units, while the maintenance costs are much reduced on account of the much greater simplicity and reliability of turbine machinery. The economy of fuel that has been due to the work of Parsons is incalculable. In the power stations of Great Britain alone the saving amounts to many millions of tons of coal per annum.




Although the steam turbine finds its greatest field of usefulness on land in power stations and in driving the electrical generators in private plants, it has many other industrial applications. Turbines were employed at a very early date for driving centrifugal pumps, fans and blowers, all of which were naturally suitable for direct operation by a high-speed prime mover. Parsons also realised that if a turbine were driven by power, instead of being used to produce it, the machine could be used as a compressor. Many compressors for air and gas were constructed by him on the principle of the reversed axial-flow turbine. Better results, however, appeared at the time to be obtainable by machines working on the centrifugal principle, so that the axial-flow compressor fell into disuse. The researches in aerodynamics carried out in recent years have now led to a better understanding of the action of the blades in an axial compressor, with the result that the earlier difficulties have been overcome, and the present tendency is to revert to the type of machine originated by Parsons, especially when the highest efficiency is imperative.

The perfection of toothed gearing, to which Parsons contributed so greatly by his invention of the 'creep' system of cutting the teeth of gearwheels, opened up the whole industrial field to the turbine, as it was then no longer confined to the driving of such high-speed machinery as could be directly coupled to it. It was successfully applied even to the driving of steel rolling mills and other duties of a similarly exacting nature, and was often used to replace ordinary steam engines for driving the main shafts of factories. Even when reciprocating engines were retained, the ability of the turbine to work with steam at very low pressures was frequently taken advantage of by installing turbines to develop extra power from the exhaust steam of the engines which had hitherto been blown to waste. Under other circumstances turbines could be used to generate the whole of the power required, and supply at the same time any desired amount of partially expanded steam at a given temperature and pressure for heating and process work. In all these developments Parsons took a leading part, providing turbine machinery to meet the most diverse requirements and thereby enabling factories and industrial undertakings to produce their own power much more cheaply and efficiently than before.




The use of the steam turbine for the propulsion of ships was among the claims made by Sir Charles Parsons in his original patent of 1884, but he confined his energies at first to the task of establishing the position of the turbine on land, and it was not until 1894 that he took steps to apply it to marine duties. His works at Heaton were then so fully occupied with turbo-generators that he decided to establish a separate organisation, with works at Wallsend-on-Tyne, to deal with the special problems involved in marine propulsion. This company, which became known later as The Parsons Marine Steam Turbine Co., Ltd., proceeded immediately with the construction of a little vessel whose fame is now historic. This was the Turbinia[1] with a length of 100 feet and a displacement of 44 tons. After much experimental work with her propellers, the Turbinia attained a speed of 34 knots, which was a very remarkable achievement, since the fastest destroyers of the time could hardly exceed 27 knots. The fact that the steam turbine was inaugurating a new era in marine practice was brought home to the public in an unmistakable manner at the great Naval Review held in 1897 to celebrate the Diamond Jubilee of Queen Victoria. A vast fleet, representing not only the might of the British Navy, but the sea-power of other leading nations as well, was assembled off Spithead when the little Turbinia, with Parsons himself in control of the machinery, created a sensation by racing down the lines of warships at a speed obviously greater than that of any other vessel afloat. The Admiralty could not ignore such a demonstration, and entrusted Parsons with the construction of a 30-knot turbine-driven destroyer, H.M.S. Viper[2], but so grudgingly was the order given that Parsons and his associates were required to deposit a sum of no less than £100,000 as a security, in case the vessel should not come up to expectations. These, however, were more than fulfilled, the Viper attaining a speed of over 37 knots when officially tested over the measured mile with turbines developing 12,000 H.P. A second turbine-driven destroyer, built about the same time, was taken over by the Admiralty and added to the Navy under the name of H.M.S. Cobra; but shortly afterwards both of these boats were lost at sea by accidents quite unconnected with the nature of their machinery, so that the little Turbinia became once again the only representative of the turbine principle afloat.

The lives of the Viper and Cobra had been brief, but their performance had attracted the attention of certain enterprising engineers connected with the Merchant Service, and in 1901 the first turbine-driven passenger vessel, the King Edward, was built for service on the river Clyde. This was followed by the Queen Alexandra for the same duties, and within the next year or two, turbine propulsion had also been adopted for the cross-channel boats Queen and Brighton. Meanwhile, in order that the advantages of turbines for warships should once more be demonstrated to the Naval authorities, The Parsons Marine Steam Turbine Co. laid down another turbine-driven destroyer which was eventually acquired for the Fleet under the name of H.M.S. Velox. The Admiralty now began to take the turbine more seriously, and when, in 1902, orders were placed for four 3000-ton cruisers, it was decided that one of them, H.M.S. Amethyst, should be fitted with turbines in order that a comparison might be made between her performance and that of the three sister vessels equipped with the usual reciprocating engines. The results were so conclusively in favour of the Amethyst that the last prejudices against turbine machinery in the Navy were overcome and the way was open for its general adoption.

The first turbine vessel to cross the Atlantic was the steam yacht Emerald, built in 1909 to the order of Sir Christopher Furness, but the next year the Allan Line ordered two 13000-ton vessels, the Virginian and Victorian, for their Liverpool-Canada passenger service, and with praiseworthy enterprise they decided that they should be propelled by turbines. The Cunard Company followed with a 30,000-ton liner, the Carmania, which once more demonstrated the superiority of the turbine by proving, on her trials in 1905, fully a knot faster than her sister ship the Caronia, equipped with reciprocating engines. By this time Parsons had won his battle for the recognition of the turbine at sea. His victory was confirmed, so far as Naval vessels were concerned, by a Committee on Naval Design appointed by the Admiralty in 1905, who advised that in future turbine machinery should be used exclusively in all classes of warships. As a consequence of this decision, turbines were adopted for the propulsion of H.M.S. Dreadnought, the fastest and most powerfully armed battleship in the world at the time.

The greatness of the contribution that Parsons had made to Naval progress will be understood from the words used by the First Lord of the Admiralty in justification of the decision to adopt turbine machinery. The turbine system, he said, had been decided on 'because of the saving in weight and reduction in the number of working parts and reduced liability to breakdown; its smooth working, ease of manipulation, saving in coal consumption at high powers, and hence in boiler-room space, and saving in engine-room complement; also because of the increased protection provided with this system, due to the engines being lower in the ship'.

Most of the reasons which caused the Admiralty to renounce reciprocating engines in favour of turbines in Naval vessels applied with equal force to a large part of the Mercantile Marine. Indeed, the conditions of service of fast liners, required to make uninterrupted passages at full speed across the ocean, enabled the turbine to make an even more advantageous showing than in war vessels, which were rarely required to navigate at full speed. In 1904 the British Government came to an arrangement with the Cunard Company, under which the latter should construct two new liners with an average speed of at least 24.5 knots, in order to be serviceable, not only as fast mail carriers but also as Naval auxiliaries in the event of war. The question of their propelling machinery was referred to a strong Commission representative both of the Admiralty and the leading shipbuilding firms, who reported definitely in favour of the turbine. This decision, coupled with that of the Admiralty to adopt turbine propulsion exclusively in the Navy, shows how enormous had been the change in practice since the first appearance of the Turbinia only ten years before. The two new liners, the Lusitania and Mauretania, were launched in 1906 and went into service the following year. The vessels were practically identical in design. The Mauretania had a displacement of 38,000 tons, and obtained a speed of 26.04 knots on her 48 hours' full-power trials with her turbines developing 70,000 horse-power. She captured the 'Blue Ribbon of the Atlantic' for the fastest crossing and held this honour for nearly a quarter of a century. Her sister vessel, the Lusitania, will be remembered as having been sunk without warning by a German submarine in 1917 with the loss of over a thousand passengers and crew. The Mauretania was taken out of commission in 1935 and broken up after a working life of 28 years. Her 70,000 H.P. by no means marked the limit of power of marine installations. In the Royal Navy H.M.S. Hood was constructed during the last war with turbines of 150,000 H.P., and even this power exceeded in recent Atlantic liners such as the Queen Mary and Queen Elizabeth.

Enough has been said to show that the success of the turbine at sea was no less striking than its achievements on land, and its supremacy over the reciprocating engine for all the most important classes of service was even more rapidly established. It permitted vessels to be driven at speeds that had previously been impossible, and enabled those speeds to be maintained in the roughest of seas. In warships the turbine machinery could be protected more effectively than engines, the fuel economy was greater and the maintenance costs less. Commercial vessels benefited similarly in speed and economy by turbine propulsion, while the space available for cargo and passengers was increased and vibration was lessened. The cumulative effect of these advantages was sufficient to establish the turbine, within a few years only, as the recognised prime mover for all the Navies of the world, as well as for all the fastest ocean liners. The subsequent introduction by Parsons of gearing between the turbines and the propellers was another great step in advance, for it not only diminished the size of the machinery and increased its efficiency, but it enabled the ordinary cargo vessel to profit equally by the employment of turbines.

The turbine, however, has never altogether succeeded in ousting the well-tried marine engine from slow-speed cargo vessels. On the contrary it did much to give the engine a new lease of life, for by the addition of a turbine to develop power from the exhaust steam of the engines, the efficiency of the machinery was considerably increased. A combination of this kind was patented by Parsons in 1906, and was first used on a commercial scale in the 10,000-ton S.S. Otaki in 1908. This vessel showed a reduction in service of 12 per cent in fuel consumption as compared with her sister ships equipped with engines only, the saving amounting to 750 tons of coal on the round voyage to New Zealand and back. The Otaki was a three-shaft vessel with the turbine alone driving the centre shaft, but in subsequent developments it has been the general practice to couple the turbine through gearing to one of the engine-driven shafts. This arrangement, in one form or another, has been exploited by various Continental manufacturers, who have associated their names with particular variants of it, but the credit of it belongs properly to Parsons. It was stated on good authority in 1926 that the efficiency of machinery for the propulsion of ships had been more than doubled during the twenty years that had then elapsed since the introduction of the turbine, the improvement being due in no small measure to the use of gearing. Progress has, of course, continued, although it may not have proceeded subsequently with the same rapidity, and the consequent aggregate reduction in the quantity of fuel consumed by the Mercantile and Naval fleets of all nations due to the work of Parsons has been incalculable.

The insistent desire of shipowners for an even greater economy of fuel led to the development of the marine oil engine, which, after the end of the war of 1914-18, began to challenge the supremacy of turbine machinery, particularly for mercantile vessels of slow and moderate speed. The turbine, however, had the advantage of much greater mechanical simplicity, and Parsons sought to bring its fuel consumption more nearly into line with that of the oil engine by urging the adoption of higher steam pressures and temperatures at sea. Although marine engineers had been converted to a belief in turbines and gearing, they had always been conservative in the matter of boiler practice. In 1926 conditions in the mercantile marine did not much exceed a pressure of 200 lb. per sq. inch and a temperature of 500° F. In Naval work matters were somewhat better, but not much, as the steam pressure in warships was only about 275 lb. Practice on land was very much more advanced. At that time many central stations were already using steam at 500 or 600 lb. pressure, superheated to 750° F. or over, while in some cases pressures of the order of 1400 lb. per sq. inch had been adopted. Parsons felt very strongly that marine engineers ought to take advantage of the economies resulting from higher pressures and temperatures. Knowing that a practical demonstration was the surest and quickest way of convincing the sceptics, he arranged for the equipment of a small passenger vessel, the King George V, with geared turbines of 3500 H.P. to work with steam at 550 lb. per sq. inch, superheated to 750° F. The steam was supplied by water-tube boilers of the Yarrow type. The King George V was the pioneer of high-pressure steam at sea. Although the installation was a comparatively small one, and the conditions of a river steamer making short trips with frequent stops were not the most favourable for the experiment, the machinery fulfilled the expectations of its designers, the full-load trials made after a short period of commercial service showing a steam consumption of only 8.01 lb. per shaft horse-power hour of the turbines. This enterprise of Parsons once more opened up a new field for marine engineers, and higher pressures at sea soon became general. Within the next few years there were a number of Atlantic and Pacific liners operating with steam at 350 and 400 lb. pressure, and in 1931 the Admiralty gave their approval to the advance in steam conditions by adopting a boiler pressure of 500 lb. per sq. inch and a temperature of 750° F. in H.M.S. Acheron. This vessel had a consumption of only 7.7 lb. of steam and 0.608 lb. of fuel per shaft horse-power hour, which constituted a record for economy in Naval work. Mercantile practice has now attained rivalry with Naval practice by the use of steam at an even higher pressure in the latest Cunard liners.




The application of the steam turbine to marine propulsion gave rise to many incidental problems, by the solution of which Parsons made notable contributions to the progress of marine engineering. One of the earliest difficulties he encountered was due to the high speed of the propellers. The first machinery of the Turbinia consisted of one turbine driving a single propeller at 2000 R.P.M. The results of the trials were disappointing. Different designs of propeller were tried but the best speed that could be obtained was only about 20 knots. It was clear, either that the turbine was not developing its rated power, or that the efficiency of the propeller was extremely low. To settle this question Parsons devised a special apparatus to measure the torque exerted by the turbine on the propeller shaft. This instrument was the prototype of the modern torsion meter, and by its use he assured himself that the fault was in the propeller and not in the turbine. About the same time similar difficulties in obtaining the anticipated speed were experienced in a new class of very fast torpedo-boats which were fitted with reciprocating engines. Both Parsons and the Naval authorities arrived at the same conclusion, namely, that the trouble was caused by the inability of the water to follow the rapidly moving propeller blades, so that a vacuous space was left behind the blade tips, with a consequent loss of propulsive power. This phenomenon, now known as 'cavitation', is also liable to occur in centrifugal pumps and water turbines when conditions are favourable to it. Parsons met his immediate difficulties by providing the Turbinia with three shafts each carrying three propellers so that the whole propulsive power was divided among nine propellers. With this alteration the vessel attained a speed of over 34 knots.

Many men would have rested content to have successfully circumvented their difficulty, but Parsons realised the importance of a thorough investigation of the whole question of cavitation, as this was clearly going to be a matter of concern to designers of high-speed vessels. He therefore constructed a tank with glass sides in which a model propeller could be run at high speeds. The propeller was strongly illuminated by intermittent light, the speed of the flashes being regulated in accordance with the revolutions of the propeller so that the blades could be made to appear stationary or only revolving very slowly. It was recognised that cavitation would be favoured by working with water near its boiling-point, so the first experiments were made with hot water. It was found, however, more convenient to attain the same result by maintaining a vacuum above the water in the tank, and the nature of cavitation was exhaustively studied in this manner. The knowledge gained by these investigations led to great improvements in the design of high-speed propellers, and the methods of study initiated by Parsons have since become generally adopted.

Closely allied with the phenomenon of cavitation is that of the erosion of propeller blades, although the connection between the two was not at first realised. Erosion had become such a serious problem that in 1915 the Admiralty appointed a Committee to report on the subject. In view of Parsons' experience of propeller design, he was requested to serve on the Committee, and it was he who suggested that the erosion was probably a secondary effect of cavitation. His view, which is now generally accepted, was that the vacuous spaces typical of cavitation were continually collapsing, causing a hammering by the water on the metal of the propeller. This. hammering might easily attain a destructive intensity owing to the absence of any appreciable quantity of air or gas in the cavity to soften the blows. It was typical of Parsons that he would accept no theory, not even own, that could not be supported by experiment, so he set himself to test his idea. The method he adopted was as simple and direct as it was ingenious. He made a hollow brass cone with a small hole in its apex which could be closed by a plate of the metal to be operated on. This cone was held face downwards in a tank, and when filled with water it was forced suddenly downwards until arrested by a rubber cushion on the bottom of the tank. The resilience of the rubber permitted the water in the cone to continue its downward motion for a moment after the cone had stopped, thus causing a vacuous space to occur at the top of the cone. This space immediately collapsed, and the returning water was found to strike the plate with a force often sufficient to puncture it. Pressures as great as 140 tons per sq. inch were obtained in this way, and the results of the experiments left no doubt that the damage met with in propeller blades could be fully accounted for by the hammering action consequent upon cavitation, as suggested by Parsons.




The steam turbine is essentially a high-speed prime mover, and it therefore shows to its best advantage when directly coupled to machinery that can be run at the economical speed of the turbine. This speed is, fortunately, suitable for a large range of electrical machines, but the smaller sizes of alternators and most continuous current generators require to run at less than the optimum turbine speed, which indeed may be altogether too high to make direct driving advisable or even practicable in many instances.

The obvious way of arranging for the speed of the turbine to be independent of that of the driven machinery is by interposing speed-reducing gear between' the two. The use of gearing in connection with steam turbines was originated by Dr de Laval in Sweden about the year 1889. He used it with great success in the small single-wheel turbines associated with his name, but Parsons was able to develop his turbines without recourse to gearing because of their lower efficient speed. He did, however, construct a geared unit in 1896, consisting of a 150 kw. alternator running at 4800 R.P.M. driven by a turbine running at 9600 R.P.M., and the next year he equipped a small steam launch with a turbine running at no less than 19,600 R.P.M. and driving two propeller shafts at 1400 R.P.M. by means of single-helical gear-wheels. Both these installations were quite successful, but for the next ten years or so Parsons made no further applications of gearing to either land or marine turbines. By that time he had firmly established the position of the steam turbine at sea. The Dreadnought, Lusitania and Mauretania were already in service, and the performances of these and other vessels had demonstrated the great superiority of the turbine over the reciprocating engine for the propulsion of all warships and the fastest mercantile vessels. But there remained a large field still to be conquered. The immense fleets of slow-speed tramp steamers and cargo ships on all the seven seas were unable to benefit from turbine propulsion because the normal speeds of their propellers were too far below the rotational speeds desirable for turbines.

The reason for the discrepancy between the most efficient speeds of a turbine and a propeller lies in the enormous difference in the density of the media-steam and water-in which they are respectively working. A turbine can only be made to run slowly with efficiency, either by constructing it with a very large diameter in order to maintain the peripheral speed of the blades, or by using a very large number of blade rows so as to reduce the steam velocity per stage. In either case the dimensions become excessive. Parsons realised that the only real solution to the problem was to be found in providing some connection between the turbine and the propeller shaft which would enable each to run at the speed most conducive to efficiency, and he therefore turned his attention again to the possibilities of mechanical gearing. He commenced by carrying out exhaustive experiments to determine what tooth-speeds could be employed and what power could be transmitted consistently with safety and durability. The results were so encouraging that new possibilities were opened up for turbine machinery both on land and sea. To make a practical test of the use of gearing in marine work, The Parsons Marine Steam Turbine Co. purchased in 1909 an old cargo vessel, the Vespasian, of 4350 tons displacement, and replaced her 750 H.P. triple expansion engines by geared turbines. The success of the experiment has become historical. With the same boilers and steam pressure, the substitution of geared turbines for the original machinery resulted in a reduction of the fuel consumption by 15 per cent. The gearing worked perfectly, and after the Vespasian had completed several years of commercial service, her hull, which was then worn out, was broken up and the turbines and gearing transferred to another vessel.

By 1919, or only ten years after the first experiments with gearing in the Vespasian, it was estimated that no ,000,000 H.P. were being transmitted through gearing in warships and merchant vessels, and as much as 25,000 H.P. had been transmitted by a single gear-wheel. The introduction of gearing in connection with marine turbines gave rise to a new problem. So long as it was the practice to couple turbines directly to the propeller shafts, it was possible to arrange that the thrust of the propeller should be largely counterbalanced by the axial pressure of the steam on the rotor blading, so that only a small differential pressure had to be carried by the thrust-block. With geared turbines no such counterbalancing was possible, and the thrust-block had the duty of transmitting the whole of the propeller thrust to the structure of the vessel. The old multi-collar thrust-block had served well enough with reciprocating engines, and had indeed been retained in the Vespasian, but the type was no longer adequate for the higher shaft speeds of turbine-driven vessels generally. Fortunately, about this time, the pivoted-pad type of thrust-block, in which the whole of the end-thrust could be carried on a single collar, was invented by Mr A. G. Michell in Australia. It was an engineering novelty and had only been made in quite small sizes, but Parsons at once realised its potentialities for marine work. He therefore constructed an experimental thrust-block on the Michell principle, designed to work with an axial pressure of 40,000 lb. and large enough for the propeller shaft of a destroyer. The result was so satisfactory that this type of thrust-block became a standard ,component of all geared marine turbine installations.

During the war of 1914-18 single-collar pivoted-pad thrust-blocks were fitted to Naval vessels totalling 10,000,000 H.P., and the construction of such a ship as H.M.S. Hood, in which 36,000 H.P. had to be transmitted through each of the four propeller shafts, would have been impossible without this type of thrust-block.

Simultaneously with the application of gearing to marine purposes, an equally bold departure was made by Parsons in land practice. He supplied a 750 B.H.P. turbine running at 2000 R.P.M. for the onerous duty of driving a rolling-mill for the production of ships' plates. The rolls had to run at 70 R.P.M., and this speed was obtained by the interposition of double reduction gearing between the turbine and the mill. The plant proved a most gratifying success, and there could no longer be any doubt that the use of mechanical gearing would enable the turbine to drive the reciprocating engine from almost its last strongholds.

In order that gear-wheels should work quietly and without deterioration under the conditions of speed and power imposed by their new duties, it was of course essential that their teeth should be extremely accurate both as to form and pitch. In the ordinary method of gear cutting, every error of pitch that may exist in the master wheel of the gear-cutting machine will necessarily be reproduced in the wheel being cut. No master wheel can be mathematically perfect, and the accuracy desired by Parsons was greater than any ordinary gear-cutting machine could provide. He therefore turned his attention to the production of better gears, and to this end he devised what is known as the 'Parsons Creep Mechanism'. By this mechanism the work-table of the machine was caused to rotate slightly faster than the master wheel, with the result that any errors existing in the latter were distributed spirally round the wheel being cut, instead of being concentrated at one part of the circumference. The consequence was that the unavoidable defects of the master wheel were, for all practical purposes, completely eliminated in the work.

This method of 'creep-cutting', invented by Parsons in 1912, created an entirely new standard of accuracy for mechanical gearing, and made it possible to produce gear-wheels that could be relied on to transmit any desired power with quietness and durability. Thenceforward the turbine was free from all limitations imposed by the speed of the driven machinery, for each could be run at its most efficient rate, the connection between the two being made by appropriate gearing. Geared turbines were soon employed as the propelling machinery for steam ships ranging from slow cargo vessels to the fastest warships and liners, for even in the case of fast ships it was recognised that high-speed turbines and gearing were more economical in service than direct-coupled machines running at a speed dictated by the requirements of the propeller. The improvement brought about by gearing may be illustrated by the following comparison. With the early direct-coupled marine turbines the steam consumption was about 15 or 16 lb. per shaft horse-power hour, while by 1923 geared installations could operate with a consumption of less than 10 lb. of steam for the same power, which could be reduced to 8 lb. or less if the steam was superheated. If we take into account the simultaneous increase of the efficiency of the propeller due to its lower speed, it is fair to say that by the introduction of gearing Parsons effected a further economy in fuel comparable with that originally brought about by the application of the turbine to marine work.

On land there was not the same scope for geared turbines as in marine practice, but the introduction of gearing has nevertheless widened the field and improved the performance of turbine machinery in many directions. Continuous current dynamos, centrifugal pumps and small alternators have in general to be run at speeds considerably below the economical speeds of small turbines. By the incorporation of gearing into the unit, these and other machines can be driven by efficient high-speed turbines, thus leaving a very small field for the reciprocating engine in industry.




The importance of the part played by Parsons in the development of efficient searchlights is better appreciated by Naval and Military technicians than by the general public. Searchlights were, of course, already in use at the commencement of Parsons' engineering career. They were employed by the British Navy in 1876, and their value was demonstrated in the Egyptian campaign of 1882. The advantage of using an accurately parabolic reflector to project the beam of light from the arc was recognized from the first, but owing to the difficulty of making a true parabolic shape, the earliest reflectors for searchlights were formed with spherical surfaces. The light was reflected from a coating of silver deposited on the back of the glass from which the mirror was made, and the glass was given an increasing thickness from the centre to the rim so that the consequent difference in refraction experienced by the rays should cause them to be projected in a fairly parallel beam. Large mirrors of this design were very heavy and expensive, and they were liable to become fractured in service owing to the differential expansion when subjected to the heat of the arc.

Parsons set himself the problem of producing at reasonable cost, a silvered reflector that should be of uniformly thin glass and of the ideal parabolic curvature. He worked out a process of manufacturing such reflectors while he was a partner in the firm of Clarke, Chapman and Co., of Gateshead, and as soon as he established his own Works at Heaton in 1889 he organised a special department for their production. By so doing' he virtually founded a new industry, and one that has contributed greatly not only to the needs of national defence, but also to those of peaceful commerce. The first parabolic reflectors for searchlights did not exceed 30 inches in diameter, but to meet the increasing demands of the Naval and Military authorities, parabolic reflectors up to more than 7 feet in diameter were successfully produced at Heaton. Concurrently with these developments in size, Parsons introduced many improvements in construction. The silvered side of the glass was protected by a coat of copper deposited electrically, and later on further protection was given by an additional backing of sheet lead reinforced by wire netting. This rendered the reflector immune from damage by exposure to oil fumes, salt water and other destructive influences met with in service. It also greatly reduced the risks of breakage. Indeed, a mirror protected in this way may remain serviceable after being pierced by a rifle bullet or a shell splinter.

Parsons, however, did not confine his efforts to the perfection of parabolic reflectors for throwing straight parallel shafts of light. For certain purposes, as for example when a large area such as a harbour or the landing ground of an aerodrome has to be illuminated, what is required is a flat divergent beam. To produce such beams, Parsons invented and devised methods for the manufacture of a most ingenious form of reflector, curved to a parabolic form in the vertical plane and to an elliptical form in the horizontal plane, both curves having a common focus. The parabolic curvature resulted in the light issuing in a beam of uniform depth, while the effect of the transverse elliptical curvature was to cause the rays first to converge into a vertical line at the secondary focus of the ellipse, and then to diverge at a predetermined angle. Searchlights equipped with such reflectors therefore not only projected a fan-shaped beam of the required type, but the whole of the light was able to pass through a narrow vertical slot situated at the secondary focus. Consequently the searchlight could be operated behind a loop-hole where its chances of being damaged by rifle fire would be very slight. Another of Parsons' inventions in connection with searchlights that has proved of the greatest value in navigation, particularly to ships passing through the Suez Canal, is the split parabolic-elliptical reflector. This is divided vertically into halves which are hinged to one another. Normally the combination acts as a single reflector, throwing one slightly diverging beam of light straight ahead from the ship. Such a beam enables the Canal to be safely traversed at night, but it would have a blinding effect on the pilot of any other vessel that might be approaching. It is to avoid this danger that the split reflector was devised. As soon as another ship is seen coming, the hinged halves of the mirror are swung apart by the manipulation of a small lever at the back, with the consequence that the beam is divided into two parts with a dark unlit space between them. The sides of the Canal are thus brilliantly illuminated, while the approaching pilot is not in any way inconvenienced by the light. Parsons constructed complete searchlight units of this kind, and in the early days they were hired out to ships at the entrance of the Canal and returned to shore at the other end for the use of ships making the reverse passage. This service enabled shipping to navigate the Canal during the hours of darkness, with a consequent saving of time and harbour dues.




The interest that Parsons took in matters connected with optics was no doubt largely hereditary, his father, Lord Rosse, having been a well known astronomer and famous as the constructor of the great 6-foot reflecting telescope at his country seat at Birr, in Ireland. An early outcome of this interest was the development of parabolic and parabolic-elliptic reflectors for searchlights, by which Parsons contributed so greatly to military and naval defence. He built up what became probably the most important business in the world devoted to the manufacture of such reflectors, but it was not until after the first great war that he turned his attention to optical work generally.

His first step was to acquire in 1921 a controlling interest in the firm of Ross, Ltd., of Clapham, London, well known as makers of binoculars and other small optical apparatus of the highest class. Here he introduced various improvements in the methods of glass grinding, but soon turned his mind to the much larger question of the manufacture of optical glass itself. Prior to 1914 an important part of the optical glass used in this country had been imported from the Continent. When this source of supply was no longer available, due to the outbreak of war, the position became serious because, quite apart from the ordinary requirements of industry, the efficiency of the fighting services could not be maintained without adequate supplies of the special kinds of glass needed for rangefinders, periscopes, field-glasses and other optical instruments necessary to war. The Government therefore took action which resulted in the establishment of an optical glass factory near Derby, and so ensured an adequate provision for the Services. More than this was indeed accomplished, for it was demonstrated that British experts could manufacture optical glass which was superior in many respects to the over-praised products of the German factories.

With the great reduction in the demand for optical glass that was brought about by the termination of the war, the Derby factory fell upon evil days, and in spite of the warning that had been received as to the danger of depending upon foreign countries for an essential war requirement, it appeared probable that the works would have to be closed. At this juncture Parsons appeared upon the scene, and inspired far more by public-spirited motives and by scientific interest than by any idea of making money, he purchased the entire factory in 192I. Under the name of the Parsons Optical Glass Company, the undertaking acquired a new lease of life, thanks to his energetic direction. The making of optical glass had always been very much of a secret process, understood by few and conducted along more or less traditional lines. Such conditions inevitably lead to a stagnation of practice, and to the conservation of somewhat primitive methods of manufacture. Parsons was not bound by the precedents of the industry, and he at once applied his wonderful mechanical and scientific knowledge to the improvement of the processes employed. He devised better ways of melting the glass and of stirring it in when molten, while he also introduced the practice of running the melted glass directly into a mould for immediate transference to the annealing furnace. By these and other improvements he was able to make exceptionally good discs of optical glass of any size required and possessing such special properties as might be demanded, Under his management the works produced about one hundred different kinds of glass for optical purposes, each best suited for some particular duty.

Parsons certainly did a great deal to establish the excellent reputation that English optical glass now enjoys all over the world, but according to his friend and colleague, Dr Gerald Stoney, F.R.S., he spent a fortune in the task, for his enterprise is said to have cost him something like £60,000. After his death the factory was acquired by the old-established firm of Chance Brothers of Birmingham, whose name is well known in connection with optical glass manufacture.

His success in producing large discs of optical glass for the objectives of astronomical telescopes led Parsons to take an increasing interest in the' telescopes themselves, the construction of which appealed both to his scientific and mechanical instincts. He had, from his childhood, been well acquainted with the Grubb family of DubIin, who had built notable astronomical instruments, and he had made glass for the lenses of some of their telescopes. During the first world war, Sir Howard Grubb and Sons, Ltd., transferred their optical works to England, establishing a factory at St Albans in Hertfordshire, but after the war their business went into liquidation and there was a likelihood of the works being closed altogether. Parsons determined to save the old-established undertaking, and in 1925 he purchased the assets of the firm and continued its activities under the name of Sir Howard Grubb, Parsons and Co. He built new works for it at Walkergate, adjacent to his turbine works at Heaton, and under his direction it started afresh upon a prosperous career. Many notable instruments have been constructed at Walk erg ate, including a 36-inch reflecting telescope for Greenwich Observatory and two 74-inch reflectors, one for the Dunlap Observatory of the University of Toronto and the other for the Radcliffe Observatory at Pretoria. These latter instruments are the largest in the British Empire.




There is always an interest in the life and personality of men whose achievements have been an outstanding contribution to the record of human progress. Parsons was undoubtedly one of these men, and his name is likely to rank in history as that of the greatest engineer that the nineteenth century produced. Although he owed his success to his own genius and enterprise, he was nevertheless fortunate in his parentage, upbringing and circumstances of life. Charles Algernon Parsons was born in London on June 13, 1854, the sixth and youngest son of the third Earl of Rosse, whose ancestors had migrated from England to Ireland at the end of the sixteenth century. The family had produced men who had made names in politics, war and science. Parsons' grandfather had been a Vice-president of the Royal Society, and his father, who was distinguished both as an engineer and an astronomer, was a President of the same learned body. The family seat of Birr Castle in King's County, Ireland, was a rendezvous for the leading scientific men of the day, so that as a boy Charles Parsons was nurtured in a thoroughly intellectual atmosphere. He was never sent to school but had, along with his brothers, the benefit of private tuition by men of such scientific calibre as Sir Robert Ball and Dr Johnstone Stoney. At the age of seventeen he entered Trinity College, Dublin, where he spent two years before proceeding to Cambridge in 1873. There was at that time no Engineering School at Cambridge, but Parsons attended such lectures as were given on Mechanism and Applied Mechanics, and he studied Mathematics with such effect that he passed out in 1877 as Eleventh Wrangler.

He commenced his engineering training by a four years' apprenticeship at the Elswick Works of Sir William Armstrong and Co. This was followed by two years with Messrs Kitson and Co. of Leeds, where he developed a four-cylinder high-speed epicycloidal steam engine that he had invented, and he also occupied himself with experiments on the propulsion of torpedoes by means of rockets. In 1884 he acquired a junior partnership in the firm of Clarke, Chapman and Co., of Gateshead-on-Tyne, and assumed charge of their newly organised electrical department. He applied himself immediately to the problem of producing a practical steam turbine, and constructed in the same year his first turbo-generator. In 1889, by which time over 300 of these machines were in service, mostly for ship-lighting, he severed his connection with Messrs Clarke, Chapman and Co., and founded his own works for the manufacture of turbines and electrical machinery at Heaton. His subsequent achievements in the development of turbine machinery for land and sea, and his enterprises in connection with optical work, have been recounted above. The manifold activities of Parsons were, however, by no means confined to the kinds of engineering by which he earned his greatest fame. His interests embraced the whole range of the physical sciences, and his knowledge of physical processes appeared universal. As a young man at Gateshead in 1885 he devised methods for the manufacture of incandescent electric lamps for the Sunbeam Lamp Co., of which he was one of the founders. His ingenuity was equal both to the production of the carbon filaments and to the exhausting of the bulbs, for which purpose he employed a mercury vacuum pump constructed to his own designs. He was also a firm believer in the possibilities of mechanical flight at a time when most engineers considered it to be an impracticable dream, and as early as 1893 he constructed a steam-driven helicopter which was able to lift itself several yards into the air. He then converted it into a monoplane by fitting it with wings of 11 feet span, and in this form it was capable ofrising to a height of about 20 feet and flying for a distance of 80 yards[3].

Another of his inventions was the 'Auxetophone'[4], a device for the amplification of musical and vocal sounds without any of the tone-distortion inseparable from reproduction by means of a mechanical diaphragm. The principle of the instrument was the production of the sound by suitably controlling the flow of compressed air through a valve, in imitation of the action of the vocal cords in the human throat. The valve could be operated by a needle travelling over a gramophone record or by any other convenient way. Auxetophones were used with success to reinforce the sounds of the 'cellos and double-bass fiddles of Sir Henry Wood's Orchestra in the Symphony Concerts at the Queen's Hall in 1906, and met with the enthusiastic approval of the great conductor. The musicians, however, objected to the consequent reduction of the number of performers, and the experiment had to be abandoned. The Auxetophone was as remarkable for its mechanical perfection as for the volume and purity of the sound it produced, but its usefulness came to an end with the invention of the amplification of sound by electrical means[5].

No account of Parsons' scientific work would be complete without some reference to the important researches he carried out with the object of making diamonds by the crystallisation of carbon[6]. This was a subject in which he was interested all his life, and he attacked the problem with his usual energy and ingenuity. To obtain pressures and temperatures at which the liquefaction of carbon might be possible, he employed a 2,500-ton hydraulic press and a battery capable of giving a current of 50,000 amperes. Another method which he devised to obtain extreme pressures and temperatures consisted in firing a bullet from a service rifle into a hole in a block of steel fixed a few inches in front of the muzzle. The carbonaceous substance to be experimented upon was placed at the bottom of the hole. By these and other means he obtained pressures up to 5000 tons per sq. inch and temperatures exceeding 15,000° C. He also repeated the experiments by which Moissan had claimed to have produced microscopic diamonds. Moissan had obtained his pressure by taking advantage of the contraction of molten iron when solidifying, but Parsons came to the conclusion that Moissan had been mistaken, the minute crystals thus obtained being merely some form of carbide. Parsons continued his researches intermittently for about twenty-five years, and, admitted that he had spent some £20,000 on them. His experiments were numbered by thousands, but he never succeeded in producing even the smallest crystal that would pass the crucial test of a diamond, namely that it should disappear without leaving the slightest trace when ignited in oxygen. He was therefore forced to the conclusion that the secret of Nature remained still to be discovered. Whatever aspect of Parsons' work is considered, one is struck by the extraordinary ability, energy and courage which he brought to bear on every problem in hand. The results he achieved have revolutionised whole branches of engineering and exercised a profound influence upon the structure of civilised life. Yet the means by which his mind was guided are, for the most part, as inexplicable as manifestations of genius always must be. His success in developing the steam turbine was certainly not the outcome of any theory of thermodynamical processes, for such theories were at the time in a rudimentary state. Nor was he ever known to make the slightest use of the formal procedure of mathematical reasoning, though his mathematical attainments were high enough to have gained special distinction for him at Cambridge. His intuition served him as an infallible guide in design, and elementary arithmetic sufficed for such calculations as he ever made. He was a profound believer in experiment, and had the faculty of devising simple experiments that would give him exactly the data he sought. As an example of his skill, he determined the power that would be required to drive the Turbinia at full speed by towing a small model of the hull across a pond by means of a fishing-rod, and his forecast proved to be practically exact. His dexterity as a mechanic was extraordinary. He delighted in the making of models, not for show, but for their utility in the demonstration of some principle in which he was interested at the time. Any material that might be at hand was made use of, and the result was always something that would work.

On Parsons' engineering courage there is no need to enlarge. A man who would take the responsibility for the 70,000 H.P. turbines of the Lusitania and Mauretania when the most powerful turbines afloat did not exceed 14,000 H.P. and who would construct a 25,000 kw. turbo-alternator for a foreign power station when his previous largest unit had a capacity of no more than 6000 kw. was certainly not lacking in boldness. There was, however, nothing of recklessness in his nature. His courage was tempered with prudence and he would never allow himself to be persuaded into any undertaking that he felt instinctively to be unsound. But once he had satisfied himself that any desirable object could be achieved, the magnitude of the step required for its attainment never deterred him for a moment. He was always anxious to make advances in practice, and his enterprise was boundless. His whole career was indeed a continuous progress into uncharted fields, undaunted by fears of failure and guided to success by an incomparable genius.

One of the most delightful features of Parsons' character was his extraordinary modesty. Even when at the zenith of his fame he seemed unable to realise that his achievements had been exceptional or that his ability was anything out of the ordinary. This natural humility of his disposition led him to expect other people to possess an insight equal to his own, and he was always ready to listen to any reasonable argument and to discuss it on terms of equality. His manner was kindly, courteous and considerate to all, though he was capable of an occasional abrupt explosion of impatience with stupidity of thought or action. His public and private benefactions were many. He contributed freely of his knowledge to the proceedings of scientific and technical societies, and many of them in return conferred upon him the highest distinctions in their power. The leading European and American technical institutions also showed their appreciation of his merits by electing him to honorary membership, while nine Universities awarded him honorary degrees. The bestowal upon him of the Companionship of the Order of the Bath was followed later by a Knighthood of the same Order, and in 1927 he was given the supreme distinction of the Order of Merit, being the first engineer ever to receive this honour.

Sir Charles Parsons died on February 11, 1931, while on a cruise in the West Indies, and there then passed away one of the greatest engineers of all time. He was in his seventy-seventh year, having lived to see the fruit of his labours in the complete transformation of the methods of producing power from steam, both on land and sea. To few men is it given to accomplish so much for the material benefit of humanity, or to set so high an example to those that come after.

CHARLES PARSONS; His Life and Work by Rollo Appleyard, LONDON, CONSTABLE & CO LTD 1933

Annex 1

Parsons on Internal Combustion Turbine[7]

Quotes from CHARLES PARSONS; His Life and Work by Rollo Appleyard, LONDON, CONSTABLE & CO LTD 1933



I so well remember being told it was a "vital objection" to the Turbine-the large number of blades! "An insuperable objection!" I always think your triumph so great because of the multiplicity of your enemies! However, I am only writing this to suggest to you whether it is feasible to try your fascinating plan in one of the seven new Admiralty vessels under order with internal combustion engines. The last three of 10,000 tons displacement are yet unallocated.

We are looking forward to seeing you on November 2I, and I hope Sir John Jellicoe will be with us, it's all important he should be; he is the coming man, or rather he has come! I wish you could see your way to the continuance of the Turbine in connection with the Internal Combustion principle. Remember, we can't have funnels for future fighting! And we want the armament amidships or more amidships than boilers will allow of. It means victory to see the enemy before they see you and to be absolutely devoid of a puff of inadvertent black smoke through some accident with the oil-spraying apparatus!

Yours truly,



Bellevue Lodge,



Nov. 3, 1912.

: I do not think the internal combustion turbine will ever come in. The internal combustion turbine is an absolute impossibility.” (Response of Charles Parsons p. 178)


Had Parsons responded to Fisher’s request he might have been the inventor of the gas turbine.




[1] For details see chapt V of CHARLES PARSONS; His Life and Work by Rollo Appleyard, LONDON, CONSTABLE & CO LTD 1933

[2] For details of Cobra and Viper see chapt VI of Appleyard

[3] “In the summer of 1893 Parsons made some experiments on the effect of steam-jacketing small steam-engine cylinders, by placing the whole of the cylinder and valvechest inside the boiler. The increase of economy was so marked that he was led to try whether a small toy engine could be made to sustain its own weight in the air by the lifting-power of the plane when propelled by an airscrew on the crank-shaft. The boiler was seamless steel 2.5 inches diameter, 14 inches long, and 0.01 to 0.015 inch in thickness. The steam cylinder, single-acting, of cast steel, was 1.25 inches diameter, with a 2-inch stroke. The piston was of thin cup form, of tool steel. The admission valve was cylindrical 5l16  inch diameter, cutting off at ¾ stroke. Some parts of the engine were hard-soldered, and some were soft-soldered. The working pressure was therefore limited to about 50 lb. per square inch. The total weight of the apparatus, with its 3-oz. charge of water but without lamp or burner, was 1.25 lb. He says in his own note:

Steam was raised by placing the boiler on a spirit lamp, and when 50 lb. was registered on the gauge, and the engine started, it raised itself in the air vertically to a height of several yards-the revolutions of the engine were about 1,200 and the I.H.P. 0.25 horse-power. The same engine was then mounted on a framework of cane covered with silk forming two wings of I I feet span, and a tail, the total area being about 22 square feet. The total weight was now 3.5 lb. When launched gently from the hand in an inclined. . . direction, it took a circular course, rising to a maximum height of about 20 feet. When the steam was exhausted, it came down, having traversed 80 yards.

It was clearly seen by the experiment that for practical commercial success of this class of steam apparatus an air condenser is essential, as the weight of water used in a few minutes' run equals the total weight of engine and boiler. Without a condenser, the length of flight must be limited to a very few miles, and it would seem that the chief problem that workers in the field have to solve is to obtain an efficient and light dry-air condenser.

Photographs of this primitive aeroplane were taken at the time by Mr. Gerald Stoney, showing the engine and boiler, with the propeller revolving in a horizontal plane. A vertical sail attached to the boiler prevented its too rapid rotation from the torque of the propeller. The note by Parsons continues:

The difficulty in maintaining the steam by a lamp was not satisfactorily overcome, but very satisfactory results were obtained by using methylated spirit in the boiler instead of water, and burning the exhaust under the boiler. Great difficulty was experienced in maintaining the flame when the apparatus was flown, owing to the currents of air from the propeller.

When working with methylated spirit flame, the evaporation per square foot of heating surface reached the extraordinary figure of the equivalent of 120 lb. of water evaporated per square foot of heating surface. It seems to me that the problem of aerial flight can be attacked much more favourably by means of cigar-shaped balloons propelled by gas or oil engines.

[4] ON October 12, 1906, there was posted at the Queen's Hall, London, a Notice as follows:

The two huge trumpets, resembling ventilating shafts on an ocean steamer, which have been in use during the past week on the Queen's Hall Orchestra, have been looked upon by many Promenade Concert Patrons as part of an improved system of Ventilation. The supposed Ventilators are, however, parts of a new invention by the Honble. Charles A. Parsons called the Auxetophone, respecting which he supplies the following explanation:

The Auxetophone is a pneumatic device for increasing the volume and richness of tone of stringed instruments, and is worked by air supplied by a blower in the basement of the building. The Auxetophone consists of a small comb-like valve made of aluminium which is connected to the front wood of the instrument near the" bridge," and vibrates in response to the tones produced by the player. This valve controls the exit of the air from a small box fed from the blower into a large spiral-shaped trumpet which emits sound-waves identical in quality and intonation but richer in tone and larger in volume than those produced by the instrument itself unaided by the Auxetophone.

At the Queen's Hall, the Auxetophone has so far been applied to one Double Bass only, but it is claimed that it is also applicable to the Violoncello, Viola, and Violin, and some other stringed instruments.

The history of the invention was sketched. by Parsons himself in 1921 in a letter to Sir Ambrose Fleming. From this account it appears that Edison, in 1876, suggested an air-relay for increasing sound. The idea was further developed by Horace L. Short, and subsequently by Parsons, as described in three patents, between the years 1903-1905. Parsons says:

I worked at this subject as a hobby in my workshop at home and tried many types of valve-double beat, slide-valves with multiple openings, then a form of valve made of sheet metal on edge like a fireworks cracker, and lastly the" comb-valve "- much the best because it delivered a flat-faced sound wave into the trumpet and it is not liable to be impeded or struck by small particles of dirt. It is similar to Short's. I made valves of comb pitches from one-fiftieth of an inch for reproducing from faint phonograph records, up to some .of 0.25 inch pitch for attachment to double-bass stringed instruments. The very fine ones were made of hard gold, the rest of magnalium. The air-valve reproducer was shown at the Royal Society about 1904, on a gramophone. Professor Johnston Stoney, F.R.S., was much interested, suggested the name" Auxetophone," and treated the matter mathematically.

If the motion of the valve is expressed in a series of sine terms (Fourier), then the sound-wave produced is the first differential, and consequently the harmonics are much increased in amplitude above the fundamental, and the tone much increased in richness. This was found to be the case when used on the gramophone or when actuated from the bridge of a stringed instrument.

It was shown soon afterwards in the Library of the Royal Institution and notices appeared in the papers, and then Short's letter reached me. Previously I had not made any patent search and was not aware of his patent. Edison's had either been cited by the Patent Office or Marks and Clerk had known of it.

It appeared that Short had played an instrument on the top of the Eiffel Tower some years before. He (Short) was at that time connected with Colonel Gouroagh of the Edison Company, but when I met him he had very little money and readily assented to sell his patent to me for £700 down, and an agreement for four years at £400 per annum. Soon afterwards, the Gramophone Company of 21 City Road bought mine and Short's rights for gramophones and phonographs for all countries for £5,000. I retained the rights for musical instruments.

The valve you have (taken to pieces) was made by Short in our shops (at Heaton) and was played on a double-bass at the Promenade Concerts at the Queen's Hall all one winter about 1906.

We spent much time and money in endeavours to introduce it on violins, 'cellos, and double-bass instruments, but were eventually blocked or boycotted by the Musical Fraternity, because they found it would reduce the number of executants from one-fifth to one-tenth for the same volume of sound. I dropped the whole matter….

The limiting factor to greater magnification of sound by means of an air-valve seemed to be viscous resistance in passing through minute apertures. Experiments showed that this was very marked below 1/1000 inch aperture. Hence there results a limit to the fineness of the comb. I was never able to obtain an actual magnification of the voice by means of an air-valve. Your (Fleming's) ionic valve has solved this problem.

The three patents of Parsons were …

No. 10,468/1903. Improvements in Sound Reproducers or Intensifiers applicable to Phonographs, Gramophones, Telephones and the like.

No. 10,469/1903. Improvements in and relating to Musical Instruments.

No. 20,892/1904. Improvements in and relating to Reproducers or Resonators for Gramophones, Phonographs and the like.

In these he states that after careful consideration of the conditions, the dynamical forces, the velocities of sound-waves and the displacements, the velocities of transmission of vibrations in metals, and the velocities of flow of air and gases through small orifices, it became clear " that none of the previous experimenters have understood the problem sufficiently to make a successful apparatus." He was referring to earlier devices in the form of " relays" chiefly for intensifying the sounds of the human voIce.

The first of the patents describes his relay that operates by means of an elastic fluid, a valve comprising a stationary grating or valve-seat and a movable grating or valve-cover on the side of less pressure, opening substantially normal to the gratings, and so constructed that the area of opening is approximately proportional to the displacement of the valve; it also describes his compressed-air box containing a filter for the air. The valve-cover is " mounted on a weigh-bar in rigid connection with the reproducing style-holder of a gramophone." This weighbar is capable of oscillating, rotation ally only, about its own axis.

The second of the patents describes, amongst other details, a violin in which the sounding-board is replaced by a reproducing device controlled by a valve, " operated from the vibrations of the strings."

The third of the patents includes a description of a sound-reproducer in which a rod slides in a hole or holes, in one or both of the parts of the valve to be connected; this rod is lubricated with a viscous material, to avoid" scratching " sounds. He adds, " the viscous connection may be made with a mixture of bicycle cement and castor oil or dub bin, or any thick oil, glue, vaseline, or similar substance."

The air-pressure employed by him in his early experiments was from two to three pounds to the square inch. The supply-tube communicating between the valve and the trumpet was usually provided with a longitudinal dividing strip to prevent resonance.

The weigh-bar requires explanation. In some of the later auxetophones it consisted of a short piece of metal of rectangular section, having on one of its sides a projection forming a socket for gripping the gramophone needle. This bar was suspended between a pair of end-springs. The end-springs-narrow, straight, flat, and flexible-were inserted into the bar in the direction of their lengths. They were then held firmly in a pair of saw-cuts in the stiff frame of the apparatus. When thus mounted, the gramophone needle was capable of slight rotary motion, with twist of the springs.

The valve-cover was suspended between end-springs, in a manner similar to the suspension of the weigh-bar, the end-springs in this case acting as a pair of hinges enabling the valve-cover to repose with gentle pressure upon the valve-seat.

To provide for operation of the auxetophone, the weigh-bar had to be linked to the valve-cover in such a manner as to allow the opening and closing of the valve to follow the motion of the gramophone needle. Parsons found that if this link was a stiff continuous rod fixed at its ends it transmitted vibrations of high-frequency, including those corresponding to squeaks, scratches, scrapings, and other intolerable noises. His genius showed itself in devising a link formed of a rod passing through a partially yielding substance that, while denying transmission to high-frequency vibrations, gave freedom to pleasant tones of lower frequency to pass.

As an alternative, and sometimes as an addition, he provided a small air-piston, to damp the movements of the link.

In his early auxetophone, such as he exhibited at the Royal Society and at the Royal Institution, the weigh-bar formed one piece with the thickened back of the valve-cover, which carried in a socket the gramophone needle. Pressure between cover and seat was in this type of valve controlled by a steel wire soldered at one end to the valve-cover and attached at the other to a fixed clamp carrying an adjustable eyelet filled with viscous material through which the end of the wire passed for flexible anchorage.

The first experiments of Parsons in this direction had for their object the production of a sound-box for gramophones and phonographs, which at the beginning of the twentieth century were far from being musical instruments. He began to study the matter as an engineering problem, to determine the forces and to discover what characteristics were necessary in the valve to secure musical results. His first valves, except in essentials, were more or less roughly made-he used boxwood for the valve-combs, and he moulded many of the parts out of his favourite constructional material, sealing wax. The boxwood combs were sawn out with a jewellers' hand-saw. With these primitive means he satisfied himself that his ideas could be developed and that a loud musical tone could be obtained.

He then procured watchmakers' tools and he worked with the care and accuracy that, by his preliminary investigation, he had decided were necessary for success. To ensure that the valve tongues were accurately spaced and that the correct overlaps were being obtained, he made up a measuring microscope. As the result of experiments with several types of valve, he decided upon one that proved to be much superior to the others.

To operate the auxetophone, air filtered by passing through cotton wool and fine metal gauze was pumped through a tube into a wind-box-which also contained a fine cotton-wool filter-from which it could only escape through a stationary grid with narrow openings. This stationary grid, comb, grating, or valve-seat fitted over an aperture in the wind-box. Above it, a similar grid forming the valve-cover, was hinged. Whenever this second grid was deflected outwards from the nearly closed position, it allowed air to pass through the valve-ports. The mounting had to be such that the valve-cover moved, relatively to its seat, in a direction substantially normal to it, thus sending out a flat-faced pressure wave, which passed through an outlet trunk and caused the air in a trumpet to vibrate.

In the earliest successful models of this type of auxetophone, the gramophone needle was fixed into a socket formed integrally with the valve-cover but at the far side of a torsional weigh-bar support. The needle ran in the groove on the face of the "record" disc; and the air-valve moved in sympathy with the waves recorded on the disc.

A sound-box of this type was also constructed for trial on an Edison phonograph. Here the" record" grooves are cut on the surface of a wax cylinder; they are of varying depth according to the amplitude of the recorded sound-waves. Parsons used the Edison counter-weight lever and sapphire style for picking up and for transmitting the vibrations to his auxetophone valve. A few months later he introduced a separate needle-holder, torsionally mounted in the same way as his air-valve. He then transmitted the vibration of the "record" disc of a gramophone to the air-valve through a viscous connection, consisting of a wire passing through holes in both the needle-holder and the valve-cover, the wire being coated with a medium made of bicycle-tyre cement and castor-oil. This viscous connection eliminated needle-scratch as well as the effect of eccentricty or other lack of symmetry, i.e. it was selective with regard to the vibrations it transmitted or rejected.

He also introduced at this time a spring-borne piston, arranged with a passage that allowed the air-pressure in the wind-box to act on the top of the piston to give partial balance to the otherwise simple-acting valve. This piston actuated a wire-spring lever attached to the valve-cover and rendered it possible to impart to the valve-cover the correct setting in relation to the valve-seat. In addition, the piston supplied some degree of automatic correction for slight variations of wind-pressure.

After he had completed the development of his auxetophone for gramophones and phonographs, and after the talking-machine patent rights had been sold to the Gramophone Company, he devoted himself to the application of the devices to violins, double-bass instruments, 'cellos, and harps. For reasons that were investigated mathematically by Dr. Johnstone Stoney, the application to violins was not very successful; but with double-bass instruments the results were excellent, for the musical quality and the intensity of sound from them were strikingly enhanced.

When applying the auxetophone valve to large instruments, Parsons modified the design by adopting grids of coarse pitch to suit the lower-frequency tones with which these instruments have to deal. Unfortunately, what Parsons termed the "boycott by the Musical Fraternity" discouraged him from further efforts in this direction. His experimental shop was accordingly diverted to other work.

In 1922-3, when wireless broadcasting became established, the long-neglected auxetophones were resurrected at Heaton by Mr. A. Q Carnegie, the colleague of Parsons. Carnegie applied the gramophone type of valve to a magnetic motor mechanism as a "loudspeaker." The results were superior to any "loudspeaker" then available. Parsons took interest in these experiments; but as the master-patents had expired, no monopoly could be obtained and further experimental work was judged to be likely to be unremunerative. Carnegie, however, preserved the apparatus, and it is still used as a "loud-speaker." The experimental valves made by Parsons in his home workshop with his own hands are, fortunately, in safe keeping at Heaton.

If the work of Parsons on the auxetophone had been done twenty years earlier than it was, his fame would have gone forth to the ends of the earth as a benefactor in the realm of acoustics and music. If that work had been done twenty years later than it was, he would have found a remunerative field in wireless broadcasting and in, "talking-pictures." Genius does not always exhibit discretion in timing the shot….

In 1906, gramophone machines were made for the Gramophone Company by the Victor Talking Machine Company of Camden, United States of America, who also manufactured the auxetophone and did a great deal of experimental work upon it. The chief drawback found by them was that the auxetophone was very susceptible to derangement on account of dust. The pneumatic valve" sound-box," the cabinet, and some other parts, were manufactured for several years by the Gramophone Company at Hayes….

It will thus be seen by those who have taken up subsequently the task of perfecting vibration instruments for telephony, music, and the gramophone, by analysis of the energy conditions, that in designing the auxetophone Parsons was leading the way.

The theory of the instrument attracted his old friend and tutor Dr. G. Johnstone Stoney, the famous mathematician and physicist. Parsons explained to him the fundamental principle involved in the device, and elicited from him the following letter….”

See also



[5] Magnavox started as the Commercial Wireless and Development Co., a small laboratory in Napa Valley, Calif., where Edwin Pridham and Peter Jensen invented the first loudspeaker (1922), public- address system (1915), and first completely electric phonograph (1916).


Peter Laurits Jensen (1886-1962 )Developed the first commercially available  moving coil direct radiator loudspeaker and the first speaker system designed to  match the first car radio


Peter Laurits Jensen described as the Danish Edison, and founder of Jensen Car Audio, came to the United States from Denmark in 1902. In 1903 Jensen went to Copenhagen as an apprentice in the laboratory of radio pioneer Valdemar Poulsen. Poulsen had just developed an improved transmitter for generating continuous radio waves. As his assistant, Jensen was involved in Poulsen's efforts to broadcast the human voice rather than telegraphic impulses. In 1906 Jensen made a breakthrough by linking a microphone and a transmitter circuit as a sending apparatus and connecting a crystal detector to a grounded telegraph ticker as a receiver. Jensen also experimented with broadcasting recorded music to ships at sea.


In 1909 Poulsen sold his American patent rights to the Poulsen Wireless Telephone and Telegraph Company, which reorganized as the Federal Telegraph Company. Jensen went to California to install the Poulsen equipment and met Edwin Pridham, an electrical engineer who taught him English. The reorganization left Jensen and Pridham jobless. They obtained financial backing and established their own firm, the Commercial Wireless and Development Company.


Jensen discovered the remarkable high fidelity characteristics of the moving coil when it was applied to the reproduction of sound. Although patented by 1913, it was two years later when Jensen discovered a revolutionary application for his ideas. While he was working to develop a telephone receiver, Jensen connected the telephone ear tubes to a 22' Edison Horn that he named the Magnavox -- "Great Voice." He applied his principle at a Christmas celebration surprising townspeople that heard the spoken voice amplified throughout the city. Additional capital was obtained leading to the establishment of the Magnavox Company in 1917.


During World War I, Jensen and Pridham developed an "antinoise microphone" that made the human voice audible over the roar of an airplane engine. Magnavox also won acclaim for a public address system for battleships that Jensen and Pridham invented. But the company achieved its greatest recognition in 1919, when President Woodrow Wilson addressed a crowd of 50,000 people and was heard distinctly with the aid of two Magnavox loudspeakers.


During the 1920's Magnavox moved into the production of phonographs and home radio sets. Jensen disagreed with Magnavox executives and resigned in 1925. In 1927 he founded the Jensen Radio Manufacturing Company. Jensen worked to eliminate distortion and improve fidelity in sound reproduction. In 1943 disputes with financial backers led once more to his resignation from a firm of his own creation; he then founded Jensen Industries to manufacture phonograph needles.


Jensen Car Audio milestones during Jensen's lifetime included the first commercial moving coil radiator loudspeaker in 1926. In 1930 the first permanent magnet dynamic loudspeaker, the first commercial compression-driven horn tweeter and the first molded hi-fi speaker diaphragm were unveiled. The speaker system for the first car radio produced by Paul Galvin debuted in 1931. In 1936 the bass reflex enclosed speaker was introduced. 1942 saw the first commercial coaxial two-way loudspeaker. In 1950 the first Triaxialä three-way unitary loudspeaker hit the market, and in 1952 the first horn-type super tweeter was launched. The last development under Jensen's reign was in 1960 when the first flat piston woofer was introduced. In 1956, the King of Denmark knighted Jensen. The American Institute of Radio Engineers and the Audio Engineering Society also honored him.

Lewis, W. David, "Peter L. Jensen and the Amplification of Sound" in Carroll W. Pursell, Jr., ed. Technology in America: a History of Individuals and Ideas. 2nd ed. Cambridge, Mass.: MIT Press, 1990.


[6] For details see chapt IX of Appleyard

[7] “The earliest device for extracting rotary mechanical energy from a flowing gas stream was the windmill (see above). It was followed by the smokejack, first sketched by Leonardo da Vinci and subsequently described in detail by John Wilkins, an English clergyman, in 1648. This device consisted of a number of horizontal sails that were mounted on a vertical shaft and driven by the hot air rising from a chimney. With the aid of a simple gearing system the smokejack was used to turn a roasting spit.


Various impulse and reaction air-turbine drives were developed during the 19th century. These made use of air, compressed externally by a reciprocating compressor, to drive rotary drills, saws, and other devices. Many such units are still being used, but they have little in common with the modern gas-turbine engine, which includes a compressor, combustion chamber, and turbine to make up a self-contained prime mover. The first patent to approximate such a system was issued to John Barber of England in 1791. Barber's design called for separate reciprocating compressors whose output air was directed through a fuel-fired combustion chamber. The hot jet was then played through nozzles onto an impulse wheel. The power produced was to be sufficient to drive both the compressor and an external load. No working model was ever built, but Barber's sketches and the low efficiency of the components available at the time make it clear that the device could not have worked even though it incorporated the essential components of today's gas-turbine engine.


Although many devices were subsequently proposed, the first significant advance was covered in an 1872 patent granted to F. Stolze of Germany. Dubbed the fire turbine, his machine consisted of a multistage, axial-flow air compressor that was mounted on the same shaft as a multistage, reaction turbine. Air from the compressor passed through a heat exchanger, where it was heated by the turbine exhaust gases before passing through a separately fired combustion chamber. The hot compressed air was then ducted to the turbine. Although Stolze's device anticipated almost every feature of a modern gas-turbine engine, both compressor and turbine lacked the necessary efficiencies to sustain operation at the limited turbine-inlet temperature possible at the time.” Encyclopedia Brittanica