Nikola Tesla: Mechanical Oscillator ~ US Patent # 514,169 & # 517,900 ~ Tele-Geodynamics

NIKOLA TESLA, AT 79, USES EARTH TO TRANSMIT SIGNALS: EXPECTS TO HAVE $100,000,000 WITHIN TWO YEARS

Could Destroy Empire State Building with Five Pounds of Air Pressure, He Says
by Earl Sparling

"Nikola Tesla is 79 years old, and he is one of the true geniuses of this time. Nevertheless, twenty-odd newspapermen came away from his Hotel New Yorker birthday party yesterday, which lasted six hours, feeling hesitantly that something was wrong either with the old man's mind or else with their own, for Dr. Tesla, serene in an old-fashioned Prince Albert and courtly in a way that seems to have gone out of this world, announced that: -

1. He had discovered the so-called cosmic ray in 1896, at least five years before any other scientist took it up and twenty years before it became popular among scientists, and he is now convinced that many of the cosmic particles travel fifty times faster than light, some of them 500 times faster.

Needs No Commutator

2. He has found a way to produce a direct electric current by induction and without the use of a commutator, which is something the experts in electricity have considered impossible for the past hundred years.

3. He has invented an "absolutely impossible" machine which will impart vibrations to the earth which, with proper receiving apparatus can be picked up anywhere on the earth's surface, and that this mysterious machine will allow scientists to explore the deep interior of the earth, will enable practical geologists to discover gold, coal and petroleum, and at the same time will give ships the means of navigating without compass or sextant.

Dr. Tesla has 600 to 700 patents to his name. He invented the rotary field motor, and is admittedly the seer and father of all modern electrical development. As has been his custom for five years now, he arranged his own birthday party, drank only hot milk as his part of the celebration, and made his announcements with the superb certainty of a man who knew what he was talking about, even if none of his guests did.

Tells of "Quake"

He said, among other things, that he expects to have $100,000,000 within two years, and he revealed that an earthquake which drew police and ambulances to the region of his laboratory at 48 E. Houston St. in 188.7 or 1888 was the result of a little machine he was experimenting with at that time which "you could put in your overcoat pocket."

The bewildered newspapermen pounced upon this as at least one thing they could understand and "the father of modern electricity" told what had happened as follows: -

"I was experimenting with vibrations. I had one of my machines going and I wanted to see if I could get it in tune with the vibration of the building. I put it up notch after notch. There was a peculiar cracking sound.

"I asked my assistants where did the sound come from. They did not know. I put the machine up a few more notches. There was a louder cracking sound. I knew I was approaching the vibration of the steel building. I pushed the machine a little higher.

"Suddenly all the heavy machinery in the place was flying around. I grabbed a hammer and broke the machine. The building would have been down about our ears in another few minutes. Outside in the street there was pandemonium. The police and ambulances arrived. I told my assistants to say nothing. We told the police it must have been an earthquake. That's all they ever knew about it."

Watch Out, Mr. Smith

Some shrewd reporter asked Dr. Tesla at this point what he would need to destroy the Empire State Building and the doctor replied: - "Five pounds of air pressure. If I attached the proper oscillating machine on a girder that is all the force I would need, five pounds. Vibration will do anything.- It would only be necessary to step up the vibrations of the machine to fit the natural vibration of the building and the building would come crashing down. That's why soldiers always break step crossing a bridge."

His early experiments in vibration, he explained, led to his invention of his "earth vibrating" machine. Tall and thin and ascetic face, his eyes sunken but … humorous under protruding brows, he was cagey about describing what his new machine is, although he believes it will be "the chief thing of my many inventions posterity will thank me for." …

"Two important papers, hidden for more than 60 years, are presented for the first time. The principles behind teleforce -- the particle-beam weapon, and telegeodynamics -- the mechanical earth-resonance concept for seismic exploration, are fully addressed. In addition to copies of the original documents, typed on Tesla's official stationery, this work also includes two Reader's Aid sections that guide the reader through the more technical aspects of each paper. The papers are followed by Commentary sections which provide historical background and functional explanations of the two devices. Significant newspaper articles and headline accounts are provided to document the first mention of these proposals. A large Appendix provides a wealth of related material and background information, followed by a Bibliography section and Index.

"This book contains the original texts of two unique proposals that Nikola Tesla offered up during his later years. In both cases, the technologies described trace their roots back to an earlier and tremendously productive decade in Tesla's life beginning in the early 1890s. At the time of the proposals' unveiling, "teleforce," the particle beam concept, and "telegeodynamics," the mechanical earth-resonance concept, received significant press coverage...

"On the occasion of his annual birthday celebration interview by the press on July 10, 1935 in his suite at the Hotel New Yorker, Tesla announced a method of transmitting mechanical energy accurately with minimal loss over any terrestrial distance, including a related new means of communication and a method, he claimed, which would facilitate the unerring location of underground mineral deposits. At that time he recalled the earth-trembling "quake" that brought police and ambulances rushing to the scene of his Houston Street laboratory while an experiment was in progress with one of his mechanical oscillators..."

"These are generated by Tele-Geo-Dynamic transmitters which are reciprocating engines of extreme simplicity adapted to impress isochronous vibrations upon the earth, thereby causing the propagation of corresponding rhythmical disturbances through the same which are, essentially, sound waves like those conveyed through the air and ether. . . . With a machine of this kind it will be practicable, in the differentiation of densities and aggregate states of subterranean strata and tracing their outlines on the earth's surface, to reach a precision approximating that which is secured in the investigation of the internal structure of bodies by penetrative rays. For just as the vacuum tube projects Roentgen shadows on a fluorescent screen, so the transmitter produces on the earth's surface shadows which can be detected by acoustic devices or rendered visible by optical instruments. The receiver can be made so sensitive that prospecting may be accomplished while riding in a car and without limit of distance from the transmitter."

"Much of the material presented in this book is related to the construction of a class of machine invented by Tesla and known as the reciprocating Mechanical Oscillator. Serious students of Tesla's work may recognize this machine as the basis of his system for producing electrical vibrations of a very constant period. In 1898 another variation was used to create a small earthquake in the neighborhood surrounding his Houston Street lab. Tesla called this method of transmitting mechanical energy "telegeodynamics." Included are mechanical drawings that will guide you through the construction of a working model of the Tele-Geo-Dynamic Oscillator, plus a comprehensive description of the machine in Tesla's own words."

Tele-Geo-Dynamics is the transmission of sonic or acoustic vibrations, which can be produced with comparatively simple apparatus. There is of course much sonic equipment available now for different applications, but this has little or nothing to do with Nikola Tesla's oscillator-generator. What Tesla proposed represents a new technology in sonic transmission even today.

In Tesla's oscillator-generator, a Resonance effect can be observed. Since resonance seems to be an ever increasing effect with this oscillator-generator, it can be deduced that there must be a great source of energy available through it.

Why can a resonance be created in the oscillator-generator when it cannot in a ordinary reciprocating engine? With the oscillator-generator, all governing mechanisms are eliminated. On the other hand, consider the car engine. Starting with the cylinder, a reciprocating motion is converted into rotary motion by a means of shafts, cranks, gears, drivetrains, transmissions, etc.

These parts all consume work by friction, but the greatest loss occurs in the change from reciprocating to rotary motion. At each point every varying inclination of the crank and pistons work at a disadvantage and result in loss of efficiency.

In Tesla's oscillator-generator, the piston is entirely free to move as the medium impels it without having to encounter and overcome the inertia of a moving system and in this respect the two types of engines differ radically and essentially.

This type of engine, under the influence of an applied force such as the tension of compressed air, steam, or other gases under pressure, yields an oscillation of a constant period.

The objective of the Tesla oscillator-generator is to provide a mechanism capable of converting the energy of compressed gas or steam into mechanical power. Since the oscillator-generator is denuded of all governing devices, friction is almost non-existent. In other words, the piston floats freely in air and is capable of converting all pressure into mechanical energy.

Our objective in building the engine is to provide an oscillator which under the influence of an applied force such as the elastic tension of a gas under pressure will yeild an oscillating movement which within very wide limits, will be of constant period, irrespective of variation of load, frictional losses, and other factors which in ordinary engines change in the rate of reciprocating.

It is a well-known priciple that if a spring possessing a sensible inertia is brought under tension, i.e., being stretched, and then freed, it will perform vibrations which are isochronous. As far as the period in general is concerned, it will depend on the rigidity of the spring, and its own inertia or that of the system of which it may form an immediate part. This is known as Simple Harmonic Motion.

This simple harmonic motion in the form of isochronous sound vibrations can be impressed upon the earth, causing the propagation of corresponding rhythmical disturbances through the same which pass through its remotest boundaries without attenuation so that the transmission is affected with an efficiency of one hundred percent.

He attached an oscillator no larger than an alarm clock to a steel link 2' long and 2" thick.

"For a long time nothing happened, but at last the great steel link began to tremble, increased its trembling until it dilated and contracted like a beating heart, and finally broke. Sledgehammers could not have done it", he told a reporter, "crowbars could not have done it, but a fusillade of taps, no one of which would have harmed a baby, did it."

Pleased with this beginning, he put the little oscillator in his coat pocket. Finding a half-built steel building in the Wall Street district, 10 stories high with nothing up but the steelwork, he clamped the oscillator to one of the beams.

"In a few minutes I could feel the beam trembling. Gradually the trembling increased in intensity and extended throughout the whole great mass of steel. Finally the structure began to creak and weave, and the steelworkers came to the ground panic-stricken, believing that there had been an earthquake. Before anything serious happened, I took off the oscillator, put it in my pocket, and went away. But if I had kept on 10 minutes more, I could have laid that building flat in the street. And with the same oscillator I could drop Brooklyn Bridge in less than an hour."

Sparling, Earl: N. Y. World-Telegram (July 11, 1935), "Nikola Tesla, at 79, Uses Earth to Transmit Signals; Expects to have $100,000,000 Within Two Years" ~ Here Tesla tells the story of the earthquake generated by the mechanical oscillator in his NYC laboratory in 1898, which brought the police there to stop him. They entered the lab just in time to see Tesla swing a slegehammer and smash the tiny device, which was mounted on a girder:

Nikola Tesla revealed that an earthquake which drew police and ambulances to the region of his laboratory at 48 E. Houston St., New York, in 1898, was the result of a little machine he was experimenting with at the time which "you could put in your overcoat pocket."

The bewildered newspapermen pounced upon this as at least one thing they could understand and "the father of modern electricity" told what had happened as follows:

"I was experimenting with vibrations. I had one of my machines going and I wanted to see if I could get it in tune with the vibration of the building. I put it up notch after notch. There was a peculiar cracking sound.

"I asked my assistants where did the sound come from. They did not know. I put the machine up a few more notches. There was a louder cracking sound. I knew I was approaching the vibration of the steel building. I pushed the machine a little higher. "Suddenly all the heavy machinery in the place was flying around. I grabbed a hammer and broke the machine. The building would have been about our ears in another few minutes. Outside in the street there was pandemonium.

"The police and ambulances arrived. I told my assistants to say nothing. We told the police it must have been an earthquake. That's all they ever knew about it."

Some shrewd reporter asked Dr. Tesla at this point what he would need to destroy the Empire State Building and the doctor replied: "Vibration will do anything. It would only be necessary to step up the vibrations of the machine to fit the natural vibration of the building and the building would come crashing down. That's why soldiers break step crossing a bridge."

In another interview, he boasted that, "With this principle one could split the earth in half like an apple".

Century Magazine, p. 921, Figure 2 (April 1895) ~ In 1893 Tesla constructed a preferred embodiment of the mechanical oscillator which he described as a "double compound mechanical and electrical oscillator for generating current of perfect, constant, dynamo frequency of 10 horsepower."

Allan L. Benson: World Today (Feb. 1912); "Nikola Tesla, Dreamer" ~ An illustration for the article shows an artist's conception of the planet splitting in two. The caption reads: "Tesla claims that in a few weeks he could set the earth's crust into such a state of vibration that it would rise and fall hundreds of feet and practically destroy civilization. A continuation of this process would, he says, eventually split the earth in two."

New York Sun (July 10, 1935); "New Apparatus Transmits Energy - Tesla Announces Method of Remote Control," .

N. Y. American (July 11, 1935), Section 2; "Tesla's Controlled Earth Quakes Power Through the Earth, A Startling Discovery".

New York Herald Tribune (July 11, 1935), pp. 1, 8; "Tesla, at 79, Discovers New Message Wave - At Birthday Luncheon He Announces Machine for 1-Way Communication"

New York Sun (July 11, 1935); "Nikola Tesla Describes New Invention - Art of Tele-Geodynamics"

New York Times (July 11, 1935), p. 23, col. 8; "Tesla, 79, Promises to Transmit Force - Transmission of Energy Over World,"

Be it known that I, Nikola Tesla, a citizen of the United States, residing at New York, in the county and State of New York, have invented certain new and useful Improvements in Reciprocating Engines, of which the following is a specification, reference being had to the drawing accompanying and forming a part of the same.

In the invention which forms the subject of my present application, my object has been, primarily to provide an engine, which under the influence of an applied force such as the elastic tension of steam or gas under pressure will yield an oscillatory movement which, within very wide limits, will be of constant period, irrespective of variations of load, frictional losses and other factors which in all ordinary engines produce change in the rate of reciprocation.

The further objects of the invention are to provide a mechanism, capable of converting the energy of steam or gas under pressure into mechanical power more economically than the forms of engine heretofore used, chiefly by overcoming the losses which result in these by the combination with rotating parts possessing great inertia of a reciprocating system; which also, is better adapted for use at higher temperatures and pressures, and which is capable of useful and practical application to general industrial purposes, particularly in small units.

The invention is based upon certain well known mechanical principles a statement of which will assist in a better understanding of the nature and purposes of the objects sought and results obtained. Heretofore, where the pressure of steam or any gas has been utilized and applied for the production of mechanical motion it has been customary to connect with the reciprocating or moving parts of the engine a fly-wheel or some rotary system equivalent in its effect and possessing relatively great mechanical inertia, upon which dependence was mainly placed for the maintenance of constant speed. This, while securing in a measure this object, renders impossible the attainment of the result at which I have arrived, and is attended by disadvantages which by my invention are entirely obviated. On the other hand, in certain cases, where reciprocating engines or tools have been used without a rotating system of great inertia, no attempt, so far as I know, has been made to secure conditions which would necessarily yield such results as I have reached.

It is a well known principle that if a spring possessing a sensible inertia be brought under tension, as by being stretched, and then freed it will perform vibrations which are isochronous and, as to period, in the main dependent upon the rigidity of the spring, and its own inertia or that of the system of which it may form an immediate part. This is known to be true in all cases where the force which tends to bring the spring or movable system into a given position is proportionate to the displacement.

In carrying out my invention and for securing the objects in general terms stated above, I employ the energy of steam or gas under pressure, acting through proper mechanism, to maintain in oscillation a piston, and, taking advantage of the law above stated, I connect with said piston, or cause to act upon it, a spring, under such conditions as to automatically regulate the period of the vibration, so that the alternate impulses of the power impelled piston, and the natural vibrations of the spring shall always correspond in direction and coincide in time.

While, in the practice of the invention I may employ any kind of spring or elastic body of which the law or principle of operation above defined holds true, I prefer to use an air spring, or generally speaking a confined body or cushion of elastic fluid, as the mechanical difficulties in the use of metallic springs are serious, owing mainly, to the tendency to break. Moreover, instead of permitting the piston to impinge directly upon such cushions within its own cylinder, I prefer, in order to avoid the influence of the varying pressure of the steam or gas that acts upon the piston and which might disturb the relations necessary for the maintenance of isochronous vibration, and also to better utilize the heat generated by the compression, to employ an independent plunder connected with the main piston, and a chamber or cylinder therefore, containing air which is normally, at the same pressure as the external atmosphere, for thus a spring of practically constant rigidity is obtained, but the air or gas within the cylinder may be maintained at any pressure.

In order to describe the best manner of which I am aware in which the invention is or may be carried into effect, I refer now to the accompanying drawing which represents in central cross-section an engine embodying my improvements.

A is the main cylinder in which works a piston B. Inlet ports CC pass through the sides of the cylinder, opening at the middle portion thereof and on opposite sides. Exhaust ports DD extend through the wall of the cylinder and are formed with branches that open into the interior of the cylinder on each side of the inlet ports and on opposite sides of the cylinder.

The piston B is formed with two circumferential grooves EF, which communicate through openings G in the piston with the cylinder on opposite sides of said piston respectively.

I do not consider as of special importance the particular construction and arrangement of the cylinder, the piston and the ports for controlling it, except that it is desirable that all the ports, and more especially, the exhaust ports should be made very much larger than is usually the case, so that no force due to the action of the steam or compressed air will tend to retard of affect the return of the piston in either direction.

The piston B is secured to a piston rod H, which works in suitable stuffing boxes in the heads of the cylinder A. This rod is prolonged on one side and extends through bearings V in a cylinder I suitably mounted or supported in line with the first, and within which is a disk or plunger J carried by the rod H.

The cylinder I is without ports of any kind and is air-tight except as a small leakage my occur through the bearings V, which experience has shown need not be fitted with any very considerable accuracy. The cylinder I is surrounded by a jacket K which leaves an open space or chamber around it. The bearings V in the cylinder I, extend through the jacket K which leaves an open space or chamber around it. The bearings V in the cylinder I, extend through the jacket K to the outside air and the chamber between the cylinder and jacket is made steam or air tight as by suitable packing. The main supply line L for steam or compressed air leads into this chamber, and the two pipes that lead to the cylinder A run from the said chamber, oil cups M being conveniently arranged to deliver oil into the said pipes for lubricating the piston.

In the particular form of engine shown the jacket K which contains the cylinder I is provided with a flange N by which it is screwed to the end of cylinder A. A small channel O is thus formed which has air vents P in its sides and drip pipes Q leading out from it through which the oil which collects in it is carried off.

To explain now the operation of the device above described. In the position of the parts shown, or when the piston is at the middle point of its stroke, the plunger J is at the center of the cylinder I and the air on both sides of the same is at the normal pressure of the outside atmosphere. If a source of steam or compressed air be then connected to the inlet ports CC of the cylinder A and a movement be imparted to the piston as by a sudden blow, the latter is caused to reciprocate in a manner well understood. The movement of the piston in either direction ceases when the force tending to impel it and the momentum which it has acquired are counterbalanced by the increasing pressure of the steam or compressed air in that end of the cylinder toward which it is moving and as in its movement the piston has shut off at a given point, the pressure that impelled it and established the pressure that tends to return it, it is then impelled in the opposite direction, and this action is continued as long as the requisite pressure is applied. The movements of the piston compress and rarify the air in the cylinder I at opposite ends of the same alternately. A forward stroke compresses the air ahead of the plunger J and tends to drive it forward. This action of the plunger upon the air contained in the opposite ends of the cylinder is exactly the same in principle as though a piston rod were connected to the middle point of a coiled spring, the ends of which are connected to fixed supports. Consequently the two chambers may be considered as a single spring. The compressions of the air in the cylinder I and the consequent loss of energy due mainly to the imperfect elasticity of the air, give rise to a very considerable amount of heat. This heat I utilize by conducting the steam or compressed air to the engine cylinder through the chamber formed by the jacket surrounding the air-spring cylinder. The heat thus taken up and used to raise the temperature of the steam or air acting upon the piston is availed of to increase the efficiency of the engine. In any given engine of this kind the normal pressure will produce a stroke of determined length, and this will be increased or diminished according to the increase of pressure above or the reduction of pressure below the normal.

In constructing the apparatus I allow for a variation in the length of stroke by giving to the confining cylinder I of the air spring properly determined dimensions. The greater the pressure upon the piston, the higher will be the degree of compression of the air-spring, and the consequent counteracting force upon the plunger. The rate or period of reciprocation of the piston, however, is no more dependent upon the pressure applied to drive it, than would be the period of oscillation of a pendulum permanently maintained in vibration, upon the force which periodically impels it, the effect of variations in such force being merely to produce corresponding variations in the length of stroke or amplitude of vibration respectively. The period is mainly determined by the rigidity of the air spring and the inertia of the moving system, and I may therefore secure any period of oscillation within very wide limits by properly portioning these factors, as by varying the dimensions of the air chamber which is equivalent to varying the rigidity of the spring, or by adjusting the weight of the moving parts. These conditions are all readily determinable, and an engine constructed as herein described my be made to follow the principle of operation above stated and maintain a perfectly uniform period through very much wider limits of pressure than in ordinary use it is ever likely to be subjected to, and it may be successfully used as a prime mover wherever a constant rate of oscillation or speed is required, provided the limits within which the forces tending to bring the moving system to a given position are proportionate to the displacements, are not materially exceeded. The pressure of the air confined in the cylinder when the plunger J is in its central position will always be practically that of the surrounding atmosphere, for while the cylinder is so constructed as not to permit such sudden escape of air as to sensibly impair or modify the action of the air spring there will be a slow leakage of air into or out of it around the piston rod according to the pressure therein, so that the pressure of the air on opposite sides of the plunger will always tend to remain at that of the outside atmosphere.

As an instance of the uses to which this engine may be applied I have shown its piston rod connected with a pawl R the oscillation of which drives a train of wheels. These may constitute the train of a clock or of any other mechanism. The pawl R is pivoted at R’ and its bifurcated end engages with the teeth of the ratchet wheel alternately on opposite sides of the same, one end of the pawl at each half oscillation acting to propel the wheel forward through the space of one tooth when it is engaged and locked by the other end on the last half of the oscillation which brings the first end of the oscillation into position to engage with another tooth.

Another application of the invention is to move a conductor in a magnetic field for generating electric currents, and in these and similar uses it is obvious that the characteristics of the engine render it especially adapted for use in small sizes or units.

Having now described my invention, what I claim is: [ Claims not included here ]

Be it known that I, Nikola Tesla, a citizen of the United States, residing at New York, in the county and State of New York, have invented certain new and useful Improvements in Steam Engines, of which the following is a specification, reference being had to the drawing accompanying and forming a part of the same.

Heretofore, engines, operated by the application of a force such as the elastic tension of steam or a gas under pressure, have been provided with a flywheel, or some rotary system equivalent in its effect and possessing relatively great mechanical inertia, which was relied upon for maintaining a uniform speed. I have produced, however, an engine which without such appurtenances produces, under very wide variations of pressure, load, and other disturbing causes, an oscillating movement of constant period, and have shown and described the same in [ US Patent # 514,169 ]. A description of the principle of the construction and mode of operation of this device is necessary to an understanding of my present invention. When a spring which possess a sensible inertia is brought under tension as by being stretched and then freed it will perform vibrations which are isochronous and, as to period, in the main dependent upon the rigidity of the spring, and its own inertia or that of the system of which it may form an immediate part. This is known to be true in all cases where the force which tends to bring the spring or movable system into a given position is proportionate to the displacement. In utilizing this principle for the purpose of producing reciprocating movement of a constant period, I employ the energy of steam or gas under pressure, acting through proper mechanism, to maintain in oscillation a piston, and connect with it or cause to act upon such piston a spring, preferably an air spring, under such conditions as to automatically regulate the period of the vibration, so that the alternate impulses of the power impelled piston and the natural vibrations of the spring shall always correspond in direction and coincide in time. In such an apparatus it being essential that the inertia of the moving system and the rigidity of the spring should bear certain definite relations, it is obvious that the practicable amount of work performed by the engine, when this involves the overcoming of inertia is a limitation to the applicability of the engine. I therefore propose, in order to secure all the advantages of such performances as this engine is capable of, to utilize it as the means of controlling the admission and exhaust of steam or gas under pressure in other engines generally, but more especially those forms of engine in which the piston is free to reciprocate, or in other words, is not connected with a flywheel or other like device for regulating or controlling its speed.

The drawings hereto annexed illustrate devices by means of which the invention may be carried out, Figure 1 being a central vertical section of an engine embodying my invention, and Figure 2 a similar view of a modification of the same.

Referring to Figure 1, A designates a cylinder containing a reciprocating piston B secured to a rod C extending through on or both cylinder heads.

DD; are steam ducts communicating with the cylinder at or near its ends and E is the exhaust chamber or passage located between the steam ports. The piston B is provided with the usual passages FF’ which by the movements of the piston are brought alternately into communication with the exhaust port.

G designates a slide valve which when reciprocated admits the steam or the gas by which the engine is driven, from the pipe G’ through the ducts DD’ to the ends of the cylinder.

The parts thus described may be considered as exemplifying any cylinder, piston and slide valve with the proper ports controlled thereby, but the slide valve instead of being dependent for its movement upon the piston B is connected in any manner so as to be reciprocated by the piston rod of a small engine of constant period, constructed substantially as follows: a is the cylinder, in which works the piston b. An inlet pipe c passes through the side of the cylinder at the middle portion of the same. The cylinder exhausts through ports dd into a chamber d’ provided with an opening d". the piston b is provided with two circumferential grooves e,f which communicate through openings g in the same with the cylinder chambers on opposite sides of the piston. The special construction of this device may be varied considerably, but it is desirable that all the ports, and more particularly, the exhaust ports be made larger than is usually done, so that no force due to the action of the steam or compressed air in the chambers will tend to retard or accelerate the movement of the piston in either direction. The piston b is ecured to a rod h which extends through the cylinder heads, the lower end carrying the slide valve above described and the upper end having secured to it a plunger j in a cylinder I fixed to the cylinder a and in line with it. The cylinder I is without ports of any kind and is air-tight except that leakage may occur around the piston rod which does not require to be very close fitting, and constitutes an ordinary form of air spring.

If steam or a gas under pressure be admitted through the port c to either side of the piston b, the latter, as will be understood, may be maintained in reciprocation, and it is free to move, in the sense that its movement in either direction ceases only when the force tending to impel it and the momentum which it has acquired are counterbalanced by the increasing pressure of the steam in that end of the cylinder toward which it is moving, and as in its movement the piston has shut off at a given point, the pressure that impelled it and established the pressure that tends to return it, it is then impelled in the opposite direction, and this action is continued as long as the requisite pressure is applied. The movements of the piston compress and rarify the air in the cylinder I at opposite ends of the same alternately, and this results in the heqating of the cylinder. But since a variation of the temperature of the air in the chamber would affect the rigidity of the air spring, I maintain the temperature uniform as by surrounding the cylinder I with a jacket a’ which is open to the air and filled with water.

In such an engine as that just described the normal pressure will produce a stroke of determined length, which may be increased or diminished according to the increase of pressure above or the reduction of pressure below the normal and due allowance is made in constructing the engine for a variation in the length of stroke or amplitude of vibration respectively. The period is mainly determined by the rigidity of the air spring and the inertia of the moving system and I may therefore secure any period of oscillation within very wide limits by properly adjusting these factors, as by varying the dimensions of the air chamber which may be equivalent to varying the rigidity of the spring, or by adjusting the weight of the moving parts. This latter is readily accomplished by making provision for the attachment to the piston rod of one or more weights h’. Since the only work which the small engine has to perform is the reciprocation of the valve attached to the piston rod, its load is substantially uniform and its period by reason of its construction will be constant. Whatever may be the load on the main engine therefore the steam is admitted to the cylinder at defined intervals, and thus any tendency to a change of the period of vibration in the main engine is overcome.

The control of the main engine by the engine of constant period may be effected in other ways --- of which Figure 2 will serve as an illustration. In this case the piston of the controlling engine constitutes the slide valve of the main engine, so that the latter may be considered as operated by the exhaust of the former. In the figure I have shown two cylinders AA’ placed end to end with a piston B and B’ in each. The cylinder of the controlling engine is formed by or in the casing intermediate to the two main cylinders but in all other essential respects the construction and mode of operation of the controlling engine remains as described in connection with Figure 1. The exhaust ports dd, however, constitute the inlet ports of the cylinders AA’ and the exhaust of the latter is effected through the ports m,m which are controlled by the pistons B and B’ respectively. The inlet port for the admission of the steam to the controlling engine is similar to that in Figure 1 and is indicated by the dotted circle at the center of the piston b.

An engine of the kind described possess many and important advantages. A much more perfect regulation and uniformity of action is secured, while the engine is simple and its weights for a given capacity is very greatly reduced. The reciprocating movement of the piston may be converted into rotary motion or it may be utilized and applied in any other manner desired, either directly or indirectly.

In [ US Patent # 514,169 ] I have shown and described two reciprocating engines combined in such manner that the movement or operation of one is dependent upon and controlled by the other. In the present case, however, the controlling engine is not designed nor adapted to perform other work than the regulation of the period of the other, and it is moreover an engine of defined character which has the capability of an oscillating movement of constant period.