United States Patent Office.
Wireless Telegraphy.
Specification forming part of Letters Patent, No. 706,500, dated August 8, 1902.
Original application filed October 25, 1901. Serial No. 79,959. Divided and this application filed May 10, 1902. Serial No. 106,736. (No model.)To all whom it may concern:
Be it known that I, Harry Shoemaker, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and 5State of Pennsylvania, have invented certain new and useful Improvements in Wireless Telegraphy, of which the following is a specification.
This invention relates to improvements in 10wireless telegraphy, and has special reference to an apparatus employing a receiver which is operated by static induction.
Another object of my invention is to dispense with the imperfect electrical contact or 15coherer as is now used and employ a responsive device of a much simpler and more durable construction.
Another object of the invention is the provision of a receiver which may employ solely 20the ground or the air and ground and which may be tuned so that any number may receive signals from their proper transmitter at the same time without interference.
To attain the desired objects, the invention 25consists of a system of wireless telegraphy embodying novel features of construction and combination of parts, substantially as disclosed herein.
In the drawings, Figure 1 is a diagrammatical30 view of the entire receiver, having two ground connections. Fig. 2 is a similar view, on a smaller scale, with an air and ground connection. Fig. 3 is a sectional view of the responsive device, and Fig. 4 is a bottom plan view 35thereof.
My receiving apparatus consists of the ground 1, to which is connected the wire 2, the batteries 3, wire 4, and the cap 5 of the responsive device. This cap 5 clamps and 40holds the ferrotype-diaphragm 6 in place, and secured to this cap is the rubber cup 7, the wire 4 being also connected to the diaphragm. Mounted upon the posts 8 is the strip 9 of mica or any resilient insulation material. 45This strip is so mounted as to be free to vibrate at a certain period or pitch, depending upon its length. Carried by this strip by means of a post 10 is a metal plate or disk 11, which is free to vibrate with the strip and rests adjacent to the diaphragm. Connected50 to the strip and also with its post 10 by means of a wire 12 is a spring-pointer 13, which is connected to a post 14, thus giving the pointer a slight spring motion, and upon its free end is carried the double-headed contact-point 15,55 which is adapted to always slightly contact one of the points 16 or 17, which, with the wires 18, battery 19, relay 20, wire 21, and the pointer, make a circuit. An adjusting-screw is employed to vary the pressure of the60 spring-pointer. I also employ the resistance 23, which is non-inductive and takes up the self-inductance of the relay. The armature 24 controls the sounder 25 through its circuit 26 as the contact at 15 and 16 and 17 is65 made.
From the foregoing description, taken in connection with the drawings, the operation of my improved receiver is readily understood, but, briefly stated, it is as follows: As70 the transmitter employing any form of energy is operated electrostatic waves are sent through the ground and are radiated over the surface of the earth in much the same manner as ripples in a pond when a stone is75 thrown therein—that is, it varies the potential at different points in its path. When these waves reach the receiver, a change of potential is caused at the receiver’s grounds, causing variations of potential between the80 diaphragm 6 and the disk 11, thus causing the disk 11 to vibrate the pointer which controls the relay as the points make a positive contact. The relay thus being operated operates the recorder-circuit and the signal85 possible to operate a great number of transmitters and receivers without interference, as the disk 11 has a certain natural period of vibration. If the impulses are sent in90 the same period as the natural period of the strip 9, the plate carried thereby will get its maximum swing, hence will record the character sent. Should the periods of the transmitter not be the same as the strip, the strip will not95 get its maximum swing, but will no doubt be as received. With this form of receiver it is
