In the previous post we have read how Tesla came up with a plan to draw heat from the medium and convert it into usable energy. In the two post before that I have explained what “heat from the medium” means, as this is almost (?) always misinterpreted. So we have a plan, now we need the hardware.
In case you have missed the earlier parts of this series, you can find them here
- part 1 – Intro,
- part 2 – Old science,
- part 3 – Electricity,
- part 4 – Gas law and
- part 5 – Self acting engine.
Tesla continues in “the Problem of Increasing Human Energy”:
Having recognized this truth, I began to devise means for carrying out my idea, and, after long thought, I finally conceived a combination of apparatus which should make possible the obtaining of power from the medium by a process of continuous cooling of atmospheric air. This apparatus, by continually transforming heat into mechanical work, tended to become colder and colder, and if it only were practicable to reach a very low temperature in this manner, then a sink for the heat could be produced, and energy could be derived from the medium. This seemed to be contrary to the statements of Carnot and Lord Kelvin before referred to, but I concluded from the theory of the process that such a result could be attained. This conclusion I reached, I think, in the latter part of 1883, when I was in Paris, and it was at a time when my mind was being more and more dominated by an invention which I had evolved during the preceding year, and which has since become known under the name of the "rotating magnetic field." During the few years which followed I elaborated further the plan I had imagined, and studied the working conditions, but made little headway. The commercial introduction in this country of the invention before referred to required most of my energies until 1889, when I again took up the idea of the self-acting machine. (1)
This quote helps us put this story in the overall time-line and now we can compare it to, for example, the time-line as set out in his autobiography. From which comes the following paragraph:
This would be the most efficient way of harnessing the sun to the uses of man. The consummation depended on our ability to develop electric forces of the order of those in nature. It seemed a hopeless undertaking, but I made up my mind to try it and immediately on my return to the United States, in the Summer of 1892, work was begun which was to me all the more attractive, because a means of the same kind was necessary for the successful transmission of energy without wires.
The first gratifying result was obtained in the spring of the succeeding year when I reached tensions of about 1,000,000 volts with my conical coil. That was not much in the light of the present art, but it was then considered a feat. Steady progress was made until the destruction of my laboratory by fire in 1895, as may be judged from an article by T. C. Martin which appeared in the April number of the Century Magazine. This calamity set me back in many ways and most of that year had to be devoted to planning and reconstruction. However, as soon as circumstances permitted, I returned to the task. (2)
Here Tesla discusses the development of his Magnifying Transmitter. This is one of the links that connect his Magnifying Transmitter to the self-acting engine. Another important link is that the description of the working principles of these two machines are identical. If you put it all together one can not escape the conclusion that this self-acting engine is the Magnifying Transmitter.
Furthermore I wish to draw attention to the highlighted sentence in the above quote which clearly states that the transmission of energy was not the primary goal of the Magnifying Transmitter, as some people believe. It is a by-product.
A closer investigation of the principles involved, and calculation, now showed that the result I aimed at could not be reached in a practical manner by ordinary machinery, as I had in the beginning expected. This led me, as a next step, to the study of a type of engine generally designated as "turbine," which at first seemed to offer better chances for a realization of the idea. Soon I found, however, that the turbine, too, was unsuitable.
Tesla does not say ‘turbine’ but ‘a type of engine generally designated as "turbine”’. That is an important difference as we are not dealing with any ordinary gas, but with ‘the medium’ or electricity. The turbine here refers to a flat spiral coil to which Tesla made an important improvement during this time by winding it in a bifilar manner. See US patent 512,340 which was filed on July 7th, 1893. See also my earlier post on coil geometry.
But my conclusions showed that if an engine of a peculiar kind could be brought to a high degree of perfection, the plan I had conceived was realizable, and I resolved to proceed with the development of such an engine, the primary object of which was to secure the greatest economy of transformation of heat into mechanical energy. A characteristic feature of the engine was that the work-performing piston was not connected with anything else, but was perfectly free to vibrate at an enormous rate.
A ‘piston’ for our ‘medium’ would be a coil. It’s induction compares to mechanical inertia and this inertia can compress the medium just like a piston would. There are many articles in which Tesla explains the workings of a Tesla-coil by comparing it to a piston. (for example in May, 1899: “The New Wizard of the West”). So, the characteristic feature of this system would be a free coil.
What happens is that the top of this coil is hit by a very high voltage discharge -to which atmospheric electricity gets added- and this puts the coil into a resonant vibration (converting the heat into mechanical energy). The lower end of the coil is connected to the Earth so that any tuned and grounded coil anywhere on this planet can pick up this energy. As I mentioned before; the wireless distribution is only a by-product.
Tesla continues explaining the development process.
In the process, as I had primarily conceived it, for the utilization of the energy of the ambient medium, there were five essential elements in combination, and each of these had to be newly designed and perfected, as no such machines existed. The mechanical oscillator was the first element of this combination, and having perfected this, I turned to the next, which was an air-compressor of a design in certain respects resembling that of the mechanical oscillator. Similar difficulties in the construction were again encountered, but the work was pushed vigorously, and at the close of 1894 I had completed these two elements of the combination, and thus produced an apparatus for compressing air, virtually to any desired pressure, incomparably simpler, smaller, and more efficient than the ordinary. I was just beginning work on the third element, which together with the first two would give a refrigerating machine of exceptional efficiency and simplicity, when a misfortune befell me in the burning of my laboratory, which crippled my labours and delayed me. Shortly afterwards Dr. Carl Linde announced the liquefaction of air by a self-cooling process, demonstrating that it was practicable to proceed with the cooling until liquefaction of the air took place. This was the only experimental proof which I was still wanting that energy was obtainable from the medium in the manner contemplated by me.
In order to understand what he writes we need to keep in mind that he is talking about electricity and not just any gas or air. In this short video that I made about a year ago I explain this above quote (starting at 4:50). Some have complained about the sound, but sound from such a distant past is not expected to be very clear. ;)
I hope you will enjoy the video nevertheless.
(to be continued)
Quotes from
- June, 1900: “The Problem of Increasing Human Energy”, by Nikola Tesla – or download as pdf from google docs
- 1919: “My Inventions”, by Nikola Tesla, published in the “Electrical Experimenter”