Book Reviews - Dr. Nikola Tesla - Selected Patent Wrappers from the National Archive

Dr. Nikola Tesla - Selected Patent Wrappers from the National Archive. Ratzlaff, John T. Tesla Book Co., Milbrae, Calif., 1980, 4 Vols., 922 pp., $50.00.

The Selected Patent Wrappers represents yet another means of analyzing Nikola Tesla through technical presentations supporting the patents issued to him. An issued patent, of course, presents only the barest, most essential description of an invention together with a set of claims. A "file wrapper" for a patent is a record of all iterations between the patentee and the Patent Office, through additional explanations, rewritings, and so on, to overcome objections and questions raised by the examiner up to the time of issue.

Twenty patents are presented in this publication. This reviewer divides the patents into the following five groups and shows the percent of the publication devoted to each group: wireless transmission of power and radio (49 percent); selective signaling and radio-controlled devices (23 percent); apparatus for producing currents of high frequency and potential (6 percent); spiral-flow turbine and pump (13 percent); and reciprocating electromechanical generators and engines (9 percent).

The first group, wireless power-transmission patents, is of prime interest to the work's compiler. The arguments presented by Mr. Tesla for the workability of his concept are so persuasive that those without a thorough understanding of electromagnetic-wave propagation continue to be swept up by his arguments even today — some 80 years after they were advanced. This reviewer is indebted to J.R. Johler, formerly of the National Bureau of Standards wave propagation laboratory in Boulder, Colo., for an analysis showing how Dr. Tesla was probably led astray in his experiments at Colorado Springs when he believed he had produced standing waves over the surface of the earth and set the earth into resonance oscillation.

Although Dr. Tesla was probably the first to excite Schumann resonances in the earth-ionosphere duct, as pointed out by J.R. Wait, Dr. Tesla did not recognize this as a possibility in his concept of true earth conduction. He was elated when he observed a storm traveling across the flat plains away from his experimental station in the shadow of the Rocky Mountains. His instruments detected a regular, successive rise and fall of signal level as the storm receded, and Dr. Tesla believed he was observing standing waves as the lightning strikes from the storm clouds jarred the earth into oscillation. This observation was made when his instruments were successively displaced by the crests of the wave-train produced. Johler has pointed. out, in studying the abrupt rise of the mountain range immediately to the west of Dr. Tesla's experimental station, that Tesla undoubtedly observed the effect of signal interference and reinforcement as a result of reradiation off the range front. The effect upon his instruments would have been the same.

Nikola Tesla made discoveries derived through the study of analogies in nature. His wireless power-transmission concept was illustrated by an analogy of the earth as a spherical bag of rubber filled with fluid, a small quantity of which is periodically forced in and out of it by means of a piston. Receiving devices (other pistons) at other points on the surface of the bag would respond to the pulsating changes in pressure. This reviewer will not here delineate the reasons why such an analogy does not extend into the electromagnetic domain but, regardless of the inoperability of this concept, the techniques of producing and handling large currents of high frequency and potential that Dr. Tesla used in association with his wireless power-transmission endeavors are of absorbing interest.

One of the most interesting patents in the first group is patent #1 119 732, covering his wireless power-transmission station at Wardenclyffe, Long Island, N.Y. To this reviewer's knowledge, the patent was in process for a record period - just 1 1/2 months short of 15 years! The exchanges between Dr. Tesla and his patent attorneys with the examiners over such a long period are engaging.

The two patents (#645 576 system patent and #649 621 subdivision patent for apparatus), which were the basis for the 1943 U.S. Supreme Court decision invalidating the "fundamental" Marconi radio patent, are also included here. The two Tesla patents from the second group (#723 188 and #725 605) on selective signaling are of interest because they embrace the logical-AND function. It is because of them that the logical-AND circuit was not patentable in association with modern computer technology developments. Reginald Fessenden was defeated by Tesla in a 1902 interference suit on the patents, which for years were the cornerstone of security transmission for radio-controlled weapons.

On the other hand, there were some unexpected items in the file wrappers. One is a nine-page deposition by Fritz Lowenstein in support of the development work by Dr. Tesla on his spiral-flow turbines and pumps, covered by patents in the fourth group. Lowenstein's deposition discusses his association in 1910 with Tesla at the American & British Manufacturing Company in Bridgeport, Conn., where Tesla was contracted to build a wireless station for the firm. It describes a 600-horsepower spiral-flow turbine 6 feet in diameter that has not been presented in the general literature before.

A patent that this reviewer was disappointed not to find in the group of turbines and pumps was Tesla's valvular conduit, or fluid diode. This device was developed for use with the gasoline version of his spiral-flow turbine, and it has also been used more recently in fluid computers. Little is known about Tesla's gasoline turbine. development work (at the Budd Co. in Philadelphia, in 1925) except that the turbine was not fully developed because metals with sufficient heat strength were then unavailable. Tesla's valvular conduit represents the first patent issued for a fluid device having no moving parts.

Patents in the fifth group cover devices that are not particularly noteworthy today, although they contain some rather interesting exchanges between the patentee and the examiner concerning descriptive terminology for fluid-dynamic apparatus.

Leland Anderson
Professional Engineer
Denver, Colo.