Patent GB-190622107-A (GB)
Title: Improvements in Space Telegraphy.
Inventor: CABOT SEWALL
Filed: 1906-10-06
Granted: 1907-10-05
Abstract: 22,107. Cabot, S. Nov. 18, 1905, [date applied for under Patents Act, 1901]. Telegraphs; lightning- arresters.-The transmitting and receiving apparatus in wireless telegraphy are arranged in such a way that the receiving operator may break in or interrupt the transmitting operator at a distant etation. During the downward movement of the transmitting-key, the wave - responsive device is rendered inoperative, the receiving- system is short-circuited, and the transmitting- system is connected to earth ; while at the completion of the downward movement of the key, the power circuit is completed. The connexions are reversed during the upward movement of the key, so that any signals sent from a distant receiving-station may be received between successive depressions of the key. In the system shown in Fig. 1, the transmitting-key K is shown in its normal position, the circuit of the detector P being closed at k<11>, and the circuit of the relay r being open at k, so that any received waves pass from the antenna through the secondary I<2>, inductance L, parallel branch circuit I1<11>, C1<11>, point O<1> to earth, thus influencing the detector P, and the receiving - tele - phone T. The receiving- system is of the type described in Specification No. 28,826, A.D. 1904. -- The depression of the key K opens the detector circuit at k<11> and closes a contact k in the circuit of the relay r, which attracts its armature t, thus directly earthing the antenna V and short-circuiting the receiving-system between the points o, o'. Further downward movement of the key closes the contact k<1> in the circuit of the generator A, thus producing simple harmonic oscillations in the circuit C S I', as explained in Specifications No. 27,295, A.D. 1902, and No. 25,644, A.D. 1904. To protect the generator A, fuses F and condensers C', C", having their middle plates earthed, and shunted by sparkgaps s, s<1>, are arranged as shown. The condenser C<111> affords a path of small impedance to the oscillations passing through the detector P. The electrodes of the multiple series spark-gap S, Figs. 1 and 9, are preferably made of zinc and mounted upon insulators 38<1>. In order to regulate the number of electrodes employed, the rod 40, having a spring contact 42, slides in a collar 39 and can be moved into contact with any electrode. The advantages of using zinc are that it fixes the oxygen in the nitrous acid created by the sparking, and that it gives a non-arcing gap since its vapour is non-conducting. Fig. 7 shows a modified arrangement, in which the relay r is dispensed with, the key K itself completing the earth connexion of the antenna at the points o, o', at the same time short-circuiting the receiving-system L C111 I111. The detector used is known as the Wollaston anode, and consists of a wire, large as compared with the silver-coated platinum Wollaston wire, enclosed in a capillary tube and having its end surface only exposed to an electrolyte in the cup P. As shown in Fig. 7, one electrode W of the detector is carried by the key K, so that depression of the key results in physical separation of the component parts of the detector. Figs. 2, 4, and 5 show a form of the transmitting-key. The key lever 4 is pivoted to the screws 3, and carries a contact 8 of silver or other metal whose vapour is non-conducting. The co-operating contact 9, Fig. 4, is not shown in Fig. 2. A rod 14, carrying an adjustable weight 18, is pivoted in the supports 13, and has a projection 16 by which the rod 14 is rotated through a small angle when the key 4 is depressed, thus bringing the contact-strips 19, 20 out of contact with the terminals 19<1>, 20<1> of the detector P. A single contact-strip may replace the strips 19, 20, or one electrode of the detector may be carried by an arm attached to the rod 14. The lever 4 also engages with the bent lever 30, Figs. 2 and 4, to the end of which is attached a tension spring x. When the part of the key 4 shown in Fig. 4 is raised, the spring x brings the adjustable screw 32 into contact with the plate 33, carried by the adjustably-mounted block 27, thus closing the circuit of the relay r, Fig. 1. Specification No. 29,142, A.D. 1904, is referred to.