Reprinted by David Steinberg with permission of copyright holders the British Council.
THE BRITISH COUNCIL
BY LONGMANS, GREEN AND CO.
SIR CHARLES PARSONS AND HIS WORK
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.
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
THE STEAM TURBINE
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'.
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
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.
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
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
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
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
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
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.
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
OTHER USES OF THE STEAM TURBINE ON LAND
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 STEAM TURBINE AT SEA
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 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, 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.
lives of the Viper and Cobra had been brief, but their
performance had attracted the attention of certain enterprising engineers
connected with the Merchant
first turbine vessel to cross the
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'.
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
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.
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
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
PARSONS' WORK ON SCREW PROPELLERS
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.
MECHANICAL GEARING FOR MARINE AND LAND TURBINES
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.
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
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
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
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.
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
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
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.
first step was to acquire in 1921 a controlling interest in the firm of Ross,
Ltd., of Clapham,
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.
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
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
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
Another of his inventions was the 'Auxetophone', 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.
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.
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
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
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
Charles Parsons died on
CHARLES PARSONS; His Life and Work by Rollo Appleyard, LONDON, CONSTABLE & CO LTD 1933
Parsons on Internal Combustion Turbine
Quotes from CHARLES PARSONS; His Life and Work by Rollo Appleyard, LONDON, CONSTABLE & CO LTD 1933
“DEAR SIR CHARLES,
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!
“: 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.
 For details see chapt V of CHARLES PARSONS; His Life and Work by Rollo Appleyard, LONDON, CONSTABLE & CO LTD 1933
 For details of Cobra and Viper see chapt VI of Appleyard
 “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.
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.
history of the invention was sketched. by Parsons himself in 1921 in a letter
to Sir Ambrose Fleming. From this account it appears that
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.
It appeared that Short had
played an instrument on the top of the
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.
sound-box of this type was also constructed for trial on an
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….”
Magnavox started as the
Commercial Wireless and Development Co., a small laboratory in
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
Laurits Jensen described as the Danish Edison, and founder of Jensen Car Audio,
came to the
Poulsen sold his American patent rights to the Poulsen Wireless Telephone and
Telegraph Company, which reorganized as the Federal Telegraph 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'
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.
David, "Peter L. Jensen and the
Amplification of Sound" in Carroll W. Pursell, Jr., ed. Technology in
 For details see chapt IX of Appleyard
 “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
Although many devices
were subsequently proposed, the first significant advance was covered in an
1872 patent granted to F. Stolze of