Page:United States patent 624516.pdf/3
United States Patent Office.
Guglielmo Marconi, of London, England, Assignor to the Wireless Telegraph and Signal Company, Limited, of same place.
Apparatus Employed in Wireless Telegraphy.
Specification forming part of Letters Patent, No. 624,516, dated May 9, 1899.
Application filed January 5, 1899. Serial No. 701,256. (No model.)
To all whom it may concern:
Be it known that I, Guglielmo Marconi electrician, a subject of the King of Italy, residing at 28 Mark Lane, in the city of London, England, have invented certain new and useful Improvements in Apparatus Employed in Wireless Telegraphy, of which the following is a specification.
In the specification of a former patent granted to me, No. 586,193, I described an arrangement in which the transmitter consisted of a sparking appliance having one terminal connected to an insulated conductor in the air and the other terminal to earth, while the receiver contained a sensitive tube or sensitive imperfect contact having one end connected to a similar conductor and the other end to earth. When both instruments are employed at the same station, it is found that the sensitive tube or sensitive imperfect contact is liable to injury by its close proximity to the sparking appliance. In order to obviate this objection, I inclose the receiver containing the sensitive tube or sensitive imperfect contact is liable to injury by its close proximity to the sparking appliance. In order to obviate this objection, I inclose the receiver containing the sensitive tube or sensitive imperfect contact in a box of metal having only a small opening into it, and I employ the same conductor and earth-plate for both instruments. The earth-plate is permanently connected to one terminal of the sparking appliance and to the outside of the box. The insulated conductor can be connected by plug either to the other terminal of the sparking appliance or to the other end of the imperfect contact. Where a recording instrument is employed, this cannot conveniently be placed inside the box, and in order to prevent the wires connecting it to the relay of the receiver from leading injurious oscillations to the sensitive tube I adopt the following arrangement: One terminal of the relay-circuit is connected to the inside of the box and one terminal of the recording instrument to the outside. The ends of the wires from the other instrument are connected to the ends of a coil formed from an insulated wire covered with tin-foil. This coil is outside the box, and the tin-coil is in electrical communication with it.
Figure 1 is a diagram of a combined transmitting and receiving station arranged in accordance with this invention. Fig. 2 shows the wire of which the coil B is made. Fig. 3 is a diagram similar to Fig. 1, showing a modification.
The letters, so far as they are applicable, are the same as those employed in the former specification.
a is a battery, and b an ordinary Morse key closing the circuit through the primary of a Ruhmkorff coil c, the terminals of the secondary being connected to metallic balls e. g is a battery, and h a telegraphic instrument on the derived circuit of a relay n. j is a glass tube containing metallic powder. k′' are choking-coils in the circuit through the tube. p is a trembler on the relay-circuit for tapping the tube. q is a resistance-coil. r is a batter in the relay-circuit. p′ is a resistance inserted in derivation across the terminals of the trembler p, and p2 is a resistance in a circuit connecting the vibrating contacts of the trembler. s is a resistance across the terminals of the relay-circuit. u is an aerial conductor. These arrangements are now well known and are fully described in my former specification.
According to my present invention I inclose the receiver in a metallic box A. One-twentieth of an inch is a suitable thickness for the metal. The inside of the box is connected by a wire A′ to the relay-circuit and its outside by wires A2 A3 to one terminal of the telegraphic instrument h and earth E, respectively. The other branch of the relay-circuit is connected by a wire A4, insulated from the box, to the other terminal of the instrument h.
B is a coil on the wire A4 and outside the box. It is protected from mechanical injury by a wooden case C; but this may be omitted. The coil B may contain about twenty yards of wire one seventy-fifth of an inch in diameter and have one hundred and twenty turns. The wire is insulated with gutta-percha D, which is covered with tin-foil F, as shown in Fig. 2. The tin-foil is in electric connection with the box. The coil B prevents oscillations of the transmitter from reaching the coherer at the same station through the wire A4. The aerial conductor u can be connected by a flexible conductor, plug G′, and spring-contacts H and H′ either to one of the balls e for transmitting or to