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The Soaring of Birds To the Editor of the Scientific American: I have evolved a theory concerning bird flight which seems to be novel, and as this question is apparently still open for discussion, I have decided to submit the same to your readers. A close observer of bird life knows that there must be some motive power other than that provided by the wings. While the air-current theory for soaring birds, and the wing theory for those that work the wings up and down, partially answer, how about those that almost seem to neglect spreading the wings when starting from a perch and then fly in graceful curves, downward and upward alternately, closing and opening the wings with each curve? In extending the wings the contraction of the muscles of the breast counterpulls against the shoulder joints, which are so formed as to create a vacuum or a partial vacuum. This, perhaps, may be regarded as the center of gravity; and thus, the air pressure being the same in all directions, the speed is acquired by the weight of the body back of the shoulders, less the weight forward of that point. That the muscles. of a flying bird's breast are vigorously exercised is shown by the dark color, while the breast of a domestic fowl is white. Greenfield, Iowa. Mrs. R. H. Lovely. Lodge, such a generic claim, much broader than those of the original patent for which it seems to have been substituted, should not have been permitted when the effect would be to enlarge the scope of the original invention. In the original patent Marconi limited most of his claims to a combination in a receiver for electrical oscillations of his coherer, consisting of a tube and powder, and means for shaking the powder. But inasmuch as this had been disclosed by prior publications, he applied for the reissue, and by claim 1 attempted to cover not merely the coherer of his former claims or any such coherer in a receiver, or a coherer with means for shaking the powder therein, but every form of imperfect contact device, previously disclosed by others or which might be thereafter discovered, whenever combined with any electrical signal apparatus using Hertz oscillations. This claim, if allowed, would apparently cover the prior devices of Lodge and Popoff, the latter of which is claimed to have necessitated the disclaimer and reissue. Hence the injunction did not apply to claim 1, and hence the disclaimer. Marconi and De Forest Wireless Litigation. The United States Circuit Court for the Southern District of New York recently issued an injunction against the De Forest Wireless Telegraph Company as the result of a bill in equity filed by the Marconi Wireless Telegraph Company of America, alleging infringement of Marconi's fundamental patent issued July 13, 1897, and numbered 586,193. In a very ably written opinion Judge Townsend reviews the state of the art previously to Marconi's first experiments, discusses the nature of Hertzian waves, and outlines the essentials of a commercial wireless telegraph installation. The injunction restrained the infringement of claims 3 and 5 of the Marconi patent. Claim 3, the broader of the two, reads as follows: "3. The combination, in an apparatus for communicating electrical signals, of a spark-producer at the transmitting station, an earth connection to one end of the spark-producer, an insulated conductor connected to the other end, an imperfect electrical contact at the receiving station, an earth connection to one end of the contact, an insulated conductor connected to the other end, and a circuit through the contact, substantially as and for the purpose described." The specific infringement complained of consisted in the installation and use by the De Forest Wireless Telegraph Company of its stations between New York city and Staten Island. In this particular installation the transmitting and receiving stations were equipped with high vertical wires insulated at the top. At the transmitting station were a dynamo, directly producing an alternating current, primary and secondary coils, Morse telegraph key, a spark-gap, and a condenser, most valuable adjunct to the practical operation of wireless telegraphy, but not directly involved in the suit. The high-frequency oscillations created or produced, as in the Marconi system, were radiated from the vertical wires of the transmitter and, traveling across to the receiver, impinged upon its wires and traveled down to a so-called detector or variable resistance conductor, closely corresponding in function and result with the coherer of Marconi's patent, and alleged to be its equivalent. One of the main points at issue in the suit was the use of insulated conductors, described and illustrated in Marconi's patent as metallic plates suspended by poles on wires and insulated from earth. The conductors of the 1898 system of Marconi are aerial wires insulated at the top, but connected with the earth at the bottom. Both complainant and defendant, at the time the bill was filed, used a construction where the conductors were insulated at the top, but only interrupted or obstructed as to the earth connection at the bottom. The complainant contended that defendant admitted that it is immaterial whether the aerial is insulated from the ground at the lower end. Dr. De Forest said that he preferred to employ earth connections because they permitted transmission to greater distances. Both sides agreed that the function. of the earth was not satisfactorily understood; both agreed that such an earth connection is an advantage possibly due to a guiding and strengthening force to conduct the waves to the surface of the earth so that they may glide farther through the ether. In this state of uncertainty as to the whole subject the court thought that Marconi should not be deprived of the benefit of his real invention upon any narrow limitation as to the earth connection or interruption at the lower end of the conductor, when it did not appear that even in the case of the spark-gap or tube filing obstruction the earth did not discharge the same functions as it is now supposed to discharge, and when presumably the question is merely one of degree, the strength being theoretically greater in degree where the earth connection is merely obstructed by a transformer. The rather sensational press reports which gave to Judge Townsend's decision an exaggerated effect must be taken with the proverbial pinch of salt. The injunction is not directed against the present De Forest system or against the present American De Forest Wireless Telegraph Company. It is issued against a defunct De Forest company and against the use of an apparatus which, we are informed, was an experimental and discarded form of apparatus used but a short time in 1902. It is claimed that the apparatus enjoined has never been used by the present American De Forest Wireless Telegraph Company. Indeed, De Forest and Marconi are now engaged in patent infringement liti- . gation which may continue for several years before the respective rights of the parties are decided by the courts. Almost simultaneously with the granting of the injunction, there appeared in the Patent Office Gazette a disclaimer . of the invention covered in claim 1 of the patent in suit. The patent had been reissued and clairn so broadened that its terms cover every form of imperfect contact in every possible kind of system for producing signals by means of Hertz oscillations. In view of the limitations imposed upon the Marconi coherer by the disclosures of Branly, . Popoff, and
