Fig. 312.Fig. 312.
The engraving, Fig. 312, shows, in perspective, one of the forms of apparatus used by Mr. Tesla in his earlier investigations in this field of work, and its interior construction is made plain by the sectional view shown in Fig. 313. It will be noted that the pistonPis fitted into the hollow of a cylinderCwhich is provided with channel portsO O, andI, extending all around the inside surface. In this particular apparatus there are two channelsO Ofor the outlet of the working fluid and one,I, for the inlet. The pistonPis provided with two slotsS S'at a carefully determined distance, one from the other. The tubesT Twhich are screwed into the holes drilled into the piston, establish communication between the slotsS S'and chambers on each side of the piston, each of these chambers connecting with the slot which is remote from it. The pistonPis screwed tightly on a shaftAwhich passes through fitting boxes at the end of the cylinderC. The boxes project to a carefully determined distance into the hollow of the cylinderC, thus determining the length of the stroke.
Surrounding the whole is a jacketJ. This jacket acts chiefly to diminish the sound produced by the oscillator and as a jacket when the oscillator is driven by steam, in which case a somewhat different arrangement of the magnets is employed. The apparatus here illustrated was intended for demonstration purposes, air being used as most convenient for this purpose.
A magnetic frameM Mis fastened so as to closely surround the oscillator and is provided with energizing coils which establish two strong magnetic fields on opposite sides. The magnetic frame is made up of thin sheet iron. In the intensely concentrated field thus produced, there are arranged two pairs of coilsH Hsupported in metallic frames which are screwed on the shaftAof the piston and have additional bearings in the boxesB Bon each side. The whole is mounted on a metallic base resting on two wooden blocks.
Fig. 313.Fig. 313.
The operation of the device is as follows: The working fluid being admitted through an inlet pipe to the slotIand the piston being supposed to be in the position indicated, it is sufficient, though not necessary, to give a gentle tap on one of the shaftends protruding from the boxesB. Assume that the motion imparted be such as to move the piston to the left (when looking at the diagram) then the air rushes through the slotS'and tubeTinto the chamber to the left. The pressure now drives the piston towards the right and, owing to its inertia, it overshoots the position of equilibrium and allows the air to rush through the slotSand tubeTinto the chamber to the right, while the communication to the left hand chamber is cut off, the air of the latter chamber escaping through the outletOon the left. On the return stroke a similar operation takes place on the right hand side. This oscillation is maintained continuously and the apparatus performs vibrations from a scarcely perceptible quiver amounting to no more than1of an inch, up to vibrations of a little over 3/8 of an inch, according to the air pressure and load. It is indeed interesting to see how an incandescent lamp is kept burning with the apparatus showing a scarcely perceptible quiver.
To perfect the mechanical part of the apparatus so that oscillations are maintained economically was one thing, and Mr. Tesla hinted in his lecture at the great difficulties he had first encountered to accomplish this. But to produce oscillations which would be of constant period was another task of no mean proportions. As already pointed out, Mr. Tesla obtains the constancy of period in three distinct ways. Thus, he provides properly calculated chambers, as in the case illustrated, in the oscillator itself; or he associates with the oscillator an air spring of constant resilience. But the most interesting of all, perhaps, is the maintenance of the constancy of oscillation by the reaction of the electromagnetic part of the combination. Mr. Tesla winds his coils, by preference, for high tension and associates with them a condenser, making the natural period of the combination fairly approximating to the average period at which the piston would oscillate without any particular provision being made for the constancy of period under varying pressure and load. As the piston with the coils is perfectly free to move, it is extremely susceptible to the influence of the natural vibration set up in the circuits of the coilsH H. The mechanical efficiency of the apparatus is very high owing to the fact that friction is reduced to a minimum and the weights which are moved are small; the output of the oscillator is therefore a very large one.
Theoretically considered, when the various advantages which Mr. Tesla holds out are examined, it is surprising, considering the simplicity of the arrangement, that nothing was done in thisdirection before. No doubt many inventors, at one time or other, have entertained the idea of generating currents by attaching a coil or a magnetic core to the piston of a steam engine, or generating currents by the vibrations of a tuning fork, or similar devices, but the disadvantages of such arrangements from an engineering standpoint must be obvious. Mr. Tesla, however, in the introductory remarks of his lecture, pointed out how by a series of conclusions he was driven to take up this new line of work by the necessity of producing currents of constant period and as a result of his endeavors to maintain electrical oscillation in the most simple and economical manner.
[1]A lecture delivered before the American Institute of Electrical Engineers, at Columbia College, N. Y., May 20, 1891.
[1]A lecture delivered before the American Institute of Electrical Engineers, at Columbia College, N. Y., May 20, 1891.
[2]Lecture delivered before the Institution of Electrical Engineers, London, February, 1892.
[2]Lecture delivered before the Institution of Electrical Engineers, London, February, 1892.
[3]A lecture delivered before the Franklin Institute, Philadelphia, February, 1893, and before the National Electric Light Association, St. Louis, March, 1893.
[3]A lecture delivered before the Franklin Institute, Philadelphia, February, 1893, and before the National Electric Light Association, St. Louis, March, 1893.
[4]See pages 153-4 5.
[4]See pages 153-4 5.
[5]It is thought necessary to remark that, although the induction coil may give quite a good result when operated with such rapidly alternating currents, yet its construction, quite irrespective of the iron core, makes it very unfit for such high frequencies, and to obtain the best results the construction should be greatly modified.
[5]It is thought necessary to remark that, although the induction coil may give quite a good result when operated with such rapidly alternating currents, yet its construction, quite irrespective of the iron core, makes it very unfit for such high frequencies, and to obtain the best results the construction should be greatly modified.
[6]Article by Mr. Tesla inThe Electrical Engineer, N. Y., May 6, 1891.
[6]Article by Mr. Tesla inThe Electrical Engineer, N. Y., May 6, 1891.
[7]Article by Mr. Tesla inThe Electrical Engineerof Dec. 23d, 1891.
[7]Article by Mr. Tesla inThe Electrical Engineerof Dec. 23d, 1891.
[8]Article by Mr. Tesla inThe Electrical Engineer. N. Y., July 1, 1891.
[8]Article by Mr. Tesla inThe Electrical Engineer. N. Y., July 1, 1891.
[9]Abstract of a paper read before Physical Society of London.
[9]Abstract of a paper read before Physical Society of London.
[9]Article by Mr. Tesla inThe Electrical Engineer, N. Y., August 26, 1891.
[9]Article by Mr. Tesla inThe Electrical Engineer, N. Y., August 26, 1891.
[10]Note by Prof. J. J. Thomson in the LondonElectrician, July 24, 1891.
[10]Note by Prof. J. J. Thomson in the LondonElectrician, July 24, 1891.
[11]Mr. Tesla's experiments, as the careful reader of his three lectures will perceive, have revealed a very important fact which is taken advantage of in this invention. Namely, he has shown that in a condenser a considerable amount of energy may be wasted, and the condenser may break down merely because gaseous matter is present between the surfaces. A number of experiments are described in the lectures, which bring out this fact forcibly and serve as a guide in the operation of high tension apparatus. But besides bearing upon this point, these experiments also throw a light upon investigations of a purely scientific nature and explain now the lack of harmony among the observations of various investigators. Mr. Tesla shows that in a fluid such as oil the losses are very small as compared with those incurred in a gas.
[11]Mr. Tesla's experiments, as the careful reader of his three lectures will perceive, have revealed a very important fact which is taken advantage of in this invention. Namely, he has shown that in a condenser a considerable amount of energy may be wasted, and the condenser may break down merely because gaseous matter is present between the surfaces. A number of experiments are described in the lectures, which bring out this fact forcibly and serve as a guide in the operation of high tension apparatus. But besides bearing upon this point, these experiments also throw a light upon investigations of a purely scientific nature and explain now the lack of harmony among the observations of various investigators. Mr. Tesla shows that in a fluid such as oil the losses are very small as compared with those incurred in a gas.
[12]It will, of course, be inferred from the nature of these devices that the vibration obtained in this manner is very slow owing to the inability of the iron to follow rapid changes in temperature. In an interview with Mr. Tesla on this subject, the compiler learned of an experiment which will interest students. A simple horseshoe magnet is taken and a piece of sheet iron bent in the form of an L is brought in contact with one of the poles and placed in such a position that it is kept in the attraction of the opposite pole delicately suspended. A spirit lamp is placed under the sheet iron piece and when the iron is heated to a certain temperature it is easily set in vibration oscillating as rapidly as 400 to 500 times a minute. The experiment is very easily performed and is interesting principally on account of the very rapid rate of vibration.
[12]It will, of course, be inferred from the nature of these devices that the vibration obtained in this manner is very slow owing to the inability of the iron to follow rapid changes in temperature. In an interview with Mr. Tesla on this subject, the compiler learned of an experiment which will interest students. A simple horseshoe magnet is taken and a piece of sheet iron bent in the form of an L is brought in contact with one of the poles and placed in such a position that it is kept in the attraction of the opposite pole delicately suspended. A spirit lamp is placed under the sheet iron piece and when the iron is heated to a certain temperature it is easily set in vibration oscillating as rapidly as 400 to 500 times a minute. The experiment is very easily performed and is interesting principally on account of the very rapid rate of vibration.
[13]The chief point to be noted is that Mr. Tesla attacked this problem in a way which was, from the standpoint of theory, and that of an engineer, far better than that from which some earlier trials in this direction started. The enlargement of these ideas will be found in Mr. Tesla's work on the pyromagnetic generator, treated in this chapter. The chief effort of the inventor was to economize the heat, which was accomplished by inclosing the iron in a source of heat well insulated, and by cooling the iron by means of steam, utilizing the steam over again. The construction also permits of more rapid magnetic changes per unit of time, meaning larger output.
[13]The chief point to be noted is that Mr. Tesla attacked this problem in a way which was, from the standpoint of theory, and that of an engineer, far better than that from which some earlier trials in this direction started. The enlargement of these ideas will be found in Mr. Tesla's work on the pyromagnetic generator, treated in this chapter. The chief effort of the inventor was to economize the heat, which was accomplished by inclosing the iron in a source of heat well insulated, and by cooling the iron by means of steam, utilizing the steam over again. The construction also permits of more rapid magnetic changes per unit of time, meaning larger output.
[14]The compiler has learned partially from statements made on several occasions in journals and partially by personal inquiry of Mr. Tesla, that a great deal of work in this interesting line is unpublished. In these inventions as will be seen, the brushes are automatically shifted, but in the broad method barely suggested here the regulation is effected without any change in the position of the brushes. This auxiliary brush invention, it will be remembered, was very much discussed a few years ago, and it may be of interest that this work of Mr. Tesla, then unknown in this field, is now brought to light.
[14]The compiler has learned partially from statements made on several occasions in journals and partially by personal inquiry of Mr. Tesla, that a great deal of work in this interesting line is unpublished. In these inventions as will be seen, the brushes are automatically shifted, but in the broad method barely suggested here the regulation is effected without any change in the position of the brushes. This auxiliary brush invention, it will be remembered, was very much discussed a few years ago, and it may be of interest that this work of Mr. Tesla, then unknown in this field, is now brought to light.
[15]Article by Mr. Tesla, contributed toThe Electrical Engineer, N. Y., Sept. 2, 1891.
[15]Article by Mr. Tesla, contributed toThe Electrical Engineer, N. Y., Sept. 2, 1891.
[16]Mr. Tesla here refers to an interesting article which appeared in July, 1865, in thePhil. Magazine, by Sir W. Thomson, in which Sir William, speaking of his "uniform electric current accumulator," assumes that for self-excitation it is desirable to subdivide the disc into an infinite number of infinitely thin spokes, in order to prevent diffusion of the current. Mr. Tesla shows that diffusion is absolutely necessary for the excitation and that when the disc is subdivided no excitation can occur.
[16]Mr. Tesla here refers to an interesting article which appeared in July, 1865, in thePhil. Magazine, by Sir W. Thomson, in which Sir William, speaking of his "uniform electric current accumulator," assumes that for self-excitation it is desirable to subdivide the disc into an infinite number of infinitely thin spokes, in order to prevent diffusion of the current. Mr. Tesla shows that diffusion is absolutely necessary for the excitation and that when the disc is subdivided no excitation can occur.
[17]See Part I, Chap. III, page 9.
[17]See Part I, Chap. III, page 9.
[18]See Part II, Chap. XXVI., page 145.
[18]See Part II, Chap. XXVI., page 145.
Alternate Current Electrostatic Apparatus392Alternating Current Generators for High Frequency152,374,224Alternating Motors and Transformers7American Institute Electrical Engineers Lecture145Anthony, W. A., Tests of Tesla Motors8Apparatus for Producing High Vacua276Arc Lighting, Tesla Direct, System451Auxiliary Brush Regulation438Biography, Tesla4Brush, Anti-Sparking432Brush, Third, Regulation438Brush, Phenomena in High Vacuum226Carborundum Button for Tesla Lamps140,253Commutator, Anti-Sparking432Combination of Synchronizing and Torque Motor95Condensers with Plates in Oil418Conversion with Disruptive Discharge193,204,303Current or Dynamic Electricity Phenomena327Direct Current Arc Lighting451Dischargers, Forms of305Disruptive Discharge Coil207,221Disruptive Discharge Phenomena212Dynamos, Improved Direct Current448Early Phase Motors477Effects with High Frequency and High Potential Currents119Electrical Congress Lecture, Chicago486Electric Resonance340Electric Discharges in Vacuum Tubes396Electrolytic Registering Meter420Eye, Observations on the294Flames, Electrostatic, Non-Consuming166,272Forbes Unipolar Generator468,474Franklin Institute Lecture294Generators, Pyromagnetic429High Potential, High Frequency:Brush Phenomena in High Vacuum226Carborundum Buttons140,253Disruptive Discharge Phenomena212Flames, Electrostatic, Non-Consuming166,272Impedance, Novel Phenomena194,338Lighting Lamps Through Body359Luminous Effects with Gases368"Massage" with Currents394Motor with Single Wire234,330"No Wire" Motors235Oil Insulation of Induction Coils173,221Ozone, Production of171Phosphorescence367Physiological Effects162,394Resonance340Spinning Filament168Streaming Discharges of High Tension Coil155,163Telegraphy without Wires346Impedance, Novel Phenomena194,338Improvements in Unipolar Generators465Improved Direct Current Dynamos and Motors448Induction Motors92Institution Electrical Engineers Lecture198Lamps and Motor operated on a Single Wire330Lamps with Single Straight Fiber183Lamps containing only a Gas188Lamps with Refractory Button177,239,360Lamps for Simple Phosphorescence187,282,364Lecture, Tesla before:American Institute Electrical Engineers145Royal Institution124Institution Electrical Engineers198Franklin Institute and National Electric Light Association294Electrical Congress, Chicago486Lighting Lamps Through the Body359Light Phenomena with High Frequencies349Luminous Effects with Gases at Low-Pressure368"Magnetic Lag" Motor67"Massage" with Currents of High Frequency394Mechanical and Electrical Oscillators486Method of obtaining Direct from Alternating currents409Method of obtaining Difference of Phase by Magnetic Shielding71Motors:With Circuits of Different Resistance79With Closed Conductors9Combination of Synchronizing and Torque95With Condenser in Armature Circuit101With Condenser in one of the Field Circuits106With Coinciding Maxima of Magnetic Effect in Armature and Field83With "Current Lag" Artificially Secured58Early Phase477With Equal Magnetic Energies in Field and Armature81Or Generator, obtaining Desired Speed of36Improved Direct Current448Induction92"Magnetic Lag"67"No Wire"235With Phase Difference in Magnetization of Inner and Outer Parts of Core88Regulator for Rotary Current45Single Circuit, Self-starting Synchronizing50Single Phase76With Single Wire to Generator234,330Synchronizing9Thermo-Magnetic424Utilizing Continuous Current Generators31National Electric Light Association Lecture294"No Wire" Motor235Observations on the Eye294Oil, Condensers with Plates in418Oil Insulation of Induction Coils173,221Oscillators, Mechanical and Electrical486Ozone, Production of171Phenomena Produced by Electrostatic Force318Phosphorescence and Sulphide of Zinc367Physiological Effects of High Frequency162,394Polyphase Systems26Polyphase Transformer109Pyromagnetic Generators429Regulator for Rotary Current Motors45Resonance, Electric, Phenomena of340"Resultant Attraction"7Rotating Field Transformers9Rotating Magnetic Field9Royal Institution Lecture124Scope of Lectures119Single Phase Motor76Single Circuit, Self-Starting Synchronizing Motors50Spinning Filament Effects168Streaming Discharges of High Tension Coil155,163Synchronizing Motors9Telegraphy without Wires346Transformer with Shield between Primary and Secondary113Thermo-Magnetic Motors424Thomson, J. J., on Vacuum Tubes397,402,406Thomson, Sir W., Current Accumulator471Transformers:Alternating7Magnetic Shield113Polyphase109Rotating Field9Tubes:Coated with Yttria, etc.187Coated with Sulphide of Zinc, etc.290,367Unipolar Generators465Unipolar Generator, Forbes468,474Yttria, Coated Tubes187Zinc, Tubes Coated with Sulphide of367