MARCONI WIRELESS TELEGRAPH CO. OF AMERICA v. DE FOREST WIRELESS TELEGRAPH CO.

(Circuit Court, S. D. New York. April 11, 1905.)

PATENTS-INFRINGEMENT-WIRELESS TELEGRAPHIC APPARATUS.

The Marconi reissued patent No. 11,913 (original No. 586,193), for improvements in transmitting electrical impulses and signals, and in apparatus therefor, while for a combination of elements all of which were taken from the prior art, discloses the first practical wireless telegraphic system, and shows invention of a primary character, which entitles it to a broad construction and a liberal range of equivalents. As so construed, it is not limited to receiving conductors wholly insulated from the earth at both their upper and lower ends, nor to the suspended plates described, but covers also conductors consisting of aerial wires having an earth connection at the bottom. Claim 1 of the reissue in attempting to claim broadly every form of imperfect contact device in the receiver, goes beyond the original patent, and cannot be sustained, in view of the prior art. Claims 3 and 5 held infringed by the apparatus of the De Forest and Smythe patents, which cover an equivalent, imperfect contact device. Claims 8, 10, and 24 held not infringed.

Frederic H. Betts, for complainant
Philip Farnsworth, for defendant.

TOWNSEND, Circuit Judge. This suit, by bill and answer, raises the questions of the validity, and of infringement by defendant, of complainant's reissued patent No. 11,913, granted to Guglielmo Marconi June 4, 1901, for improvements in transmitting electrical impulses and signals and in apparatus therefor. This patent is the reissue of the fundamental Marconi patent, No. 586,193, dated July 13, 1897, for transmitting electrical signals. The issues involved relate to the art of wireless telegraphy, and more especially to its latest development, sometimes termed "spark telegraphy."

Prior to 1887 the dreams and forecasts of electric telegraphy without wires found realization and tangible shape in apparatus. which utilized either the conductive properties of earth or water, or the principle of induction. The Dolbear system and apparatus of 1884 will be separately considered. The conduction system was preferably employed on the banks of bodies of water, and comprised primary and secondary circuits on the opposite banks, consisting of wires stretched along the bank on either side, and connected to the ground or water, and provided with batteries and galvanometers or telegraph or telephone instruments. By means of such apparatus currents of electricity generated by the battery in the primary circuit, on one side of a stream, for example, passed to the terminal of the wire in the secondary circuit, on the other side of the stream, and, by means of circuit making and breaking connections, signals were transmitted to the receiving apparatus. The distances covered by this system were limited to one or two miles. The second method depends on the principle of induction, or the influence of one conductor on another through an insulator, based on the discovery that, if two circuits-one having a battery and being the primary

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circuit, the other being the secondary circuit-are parallel with one another, a current made or broken in the primary circuit induces a transient or momentary current in the secondary circuit. This system was utilized by apparatus similar to that employed in the conduction method, and for about the same distances. The Dolbear system so called from the name of its great inventor, Prof. Dolbear, of Tufts College-appears to have utilized the induction principle. By means of elevated conductors, vertical wires, and grounded connections, he caused electrical impulses to extend or stretch out, perhaps by means of magnetic lines of force, from a transmitting to a receiving station, and thus accomplished, for short distances, the feat of sending signals through the air without wires. These prior experiments are only relevant at this time as showing the use of batteries, telegraph keys, telephones, and circuit interrupters or breakers in wireless systems, and the discovery and disclosure, especially by Dolbear, of certain properties of electricity utilized by later inventors, and of the desirability of using elevated conductors.

The means for the later developments of wireless telegraphy were furnished in the proof by actual experiment of the correctness of certain theories promulgated by Prof. Maxwell, of Cambridge, in 1865, that electricity, like light, traversed space through the medium of ether, and that, if a spark be created by a disruptive discharge, it will spread out in waves or undulations. These waves are known as "Hertz waves" or "Hertz oscillations," from the name of their discoverer, Heinrich Hertz. He produced these waves by the use of an apparatus consisting of a radiator and a receiver equipped with rods having small metallic knobs on the ends, and separated a short distance from each other. This separation is the spark-gap, by means of which the Hertzian waves or oscillations are produced. When the transmitter or radiator is connected with a Ruhmkorff coil, or any source of high electric tension, such as an induction coil, with mechanical vibrator, or a producer of electric current, such as a dynamo, a charge of electricity is sent through the circuit which includes the spark-gap, and a spark passes across the sparkgap and creates the electrical vibration or wave called the "Hertz wave." The characteristics of these waves are explained by Dr. De Forest as follows:

"The radiations are through the ether, not the air. They are therefore independent of wind or weather, and can penetrate all substances which are not conductors. They speed outward from the transmitter, in ever widening circles, with the velocity of light. They skim over the surface of land and sea, and hence reach stations lying far below the horizon. When these waves strike an upright conductor a portion of their energy is cut out, and generates high frequency electric currents of minute power, which run down the antenna wire to earth in traversing the receiving detector. By common consent, then, such vibrations detached or traveling over a conducting surface have most appropriately been styled 'Hertzian waves. Most certainly also are they 'oscillating currents' when traversing conductors. This was Hertz' demonstration. But when an electrical system discharges, having so small a time constant that the pulsations occur at a rate of millions per second, we have very different conditions from those ordinarily classed with

alternating or oscillatory currents.

A large portion of the energy

is electrostatic, and the force there involved may be conceived as lines of electric displacement perpendicular to the conducting surface, traveling along it away from the source of energy, following any zigzag path, rounding corners, reflected wholly or in part at all such sudden changes in shape or nature of the conductor."

Marconi has fully and accurately described the peculiarities of these oscillations as follows:

"The main character or feature of Hertzian waves is that they can be transmitted and received through space and through certain bodies, and that they follow the same laws which govern the propagation of light waves. They obey the laws of diffraction, reflection, and refraction, and, when following on an electrical conductor, produce certain electrical phenomena on or in the said conductor. They differ from ordinary electromagnetic induction in the fact that they become and are detached from the place or instrument of origin, and travel through space like light from a lamp or sound from a bell. Their speed is exceedingly great-in fact, the same as the speed of light; approximately 186,000 miles per second. They are thus similar to light waves, so far as they become detached from the radiator or producer, but possess the property, not possessed in the same degree by light waves, of traveling around obstacles or corners, such as mountains or the curvature of the earth, which curvature exists to such a large extent between any two positions situated, say, a thousand miles apart. Hertzian waves present the peculiarity of being reflected by electrical conductors and conducted by electrical insulators. Thus a sheet of glass or ebonite, which is called an electrical insulator, is transparent to Hertzian waves, and will let them through with perfect ease, whilst a sheet of metal or other conducting substance will reflect or absorb these waves. For this reason it is rather difficult to carry out tests or experiments concerning the propagation of electric waves or wireless telegraphy across rooms or halls, for the reason that these waves are reflected or absorbed in certain cases by the metallic fittings in the room, such as metal pipes or gilded paper or metallic picture frames, etc. Some of the special characteristics of these waves, which one encounters with them when experimenting in laboratories, tends rather to make it difficult to understand how they can be controlled with such certainty and regularity when applied for the purpose of transmitting reliable messages through space in the manner I have already explained in answer to the other questions. In order that there may be radiation in the form of a Hertzian wave or true electric wave into space, the frequency of the electrical oscillations set up in the conductors must be so high as to be reckoned at least in hundreds of thousands, or perhaps, rather, millions, per second. An analogy of this is to be found in the case of a sound wave through air. In order that this air wave may be produced, and therefore the sound, some object must strike the air with a certain rapidity or frequency. Thus, for instance, the swinging of a bell in a church steeple to and fro through the air will produce no air waves, and therefore no sound; but, if the rim of the bell is struck suddenly with a hammer, the whole bell vibrates at the rate of some hundreds or thousands per second, and affects the air with suddenness to create an air wave or sound, which is the sound of the bell which we hear. Therefore, in the same way, if the conducting bodies are simply connected to the producer of ordinary alternating currents or high tension electricity, no Hertzian wave or any other wave is produced; but, if a spark is caused to pass to or from or off said conductors in a suitable manner, then at each discharge or at each spark Hertzian waves, which are oscillations of a frequency of millions or hundreds of thousands per second, are produced and radiated into space. Hence it appears absolutely clear to me that there is no Hertzian wave telegraphy without the essential feature for producing Hertzian waves, which is the Hertzian spark."

It thus appears that, so far as known, these waves are produced only by a disrupted electrical discharge across a spark-gap; that

these oscillations are characterized by some conditions similar to those of electric waves, and others peculiar to light waves; that they differ from the impulses of the prior art, in that, while those stretched out in horizontal lines from the transmitting source of energy to the receiver, these waves are detached from the point of production, and travel through or are propagated in the ether, and around, through, or over the surfaces of intervening objects. While, however, they pass through materials which operate as insulators for electric currents, and are arrested by conductors of electric currents, yet, when they once impinge upon a receiving wire, they exhibit in their conduct and the laws of their operation the manifestations of electrical currents of high frequency oscillations. The present systems of spark telegraphy owe their origin and practical commercial development to this great discovery by Hertz.

Marconi, referring to his apparatus, says:

"According to this invention, electrical signals, actions, or manifestations are transmitted [through the air, earth, or water] by means of oscillations of high frequency, such as have been called 'Hertz rays' or 'Hertz oscillations." All line-wires may be dispensed with."

And referring to the prior art, he says:

"I am aware of the publication of Professor Lodge of 1894, at London, England, entitled "The Work of Hertz,' and the description therein of various instruments in connection with manifestations of Hertz oscillations. I am also aware of the papers by Professor Popoff in the 'Proceedings of the Phys ical and Chemical Society of Russia' in 1895 or 1896. But in neither of these is there described a complete system or mechanism capable of artificially producing Hertz oscillations, and forming the same into and propagating them as definite signals, and capable of receiving and reproducing telegraphically such definite signals; nor has any system been described, to my knowledge, in which a Hertz oscillator at a transmitting station and an imperfect-contact instrument at a receiving station are both arranged with one terminal to earth and the other elevated or insulated; nor am I aware that prior to my invention any practical form of self-recovering imperfect-contact instrument has been described.

"I believe that I am the first to discover and use any practical means for effective telegraphic transmission and intelligible reception of signals produced by artificially formed Hertz oscillations."

These means comprise a transmitting and a receiving station equipped with signaling apparatus, which are shown by the following copies of figures 1 and 4 of the patent drawings: