1841.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



239 



ordinary telegraph, viz. the rapidity with which the sig- 

 nals may be made to follow each other. Thirty signals 

 may be conveniently made in a minute ; that number 

 cannot be made by the ordinary telegraph. There is one 

 thing I will take the opportunity to mention— I have 

 been confining the attention of the Committee to the 

 telegraph now working on the Great Western Railway, 

 but having lately occupied myself in carrying into ellect 

 numerous improvements which have suggested them- 

 selves to rae, I have, conjointly with Mr. Cooke, who has 

 turned his attention greatly to the same subject, obtained 

 a new patent for a telegraphic arrangement, which I 

 think will present very great advantages over that which 

 at present exists. It can be applied without entailing 

 any additional expense of consequence to the line now 

 laid down, it will only be necessary to substitute the new 

 for the former instruments. This new apparatus requires 

 only a single pair of wires to effect all which the present 

 one does with five, so that three independent telegraphs 

 may be immediately placed on the line of the Great 

 Western ; it presents in the same place all the letters of 

 the alphabet according to any order of succession, and 

 the apparatus is so extremely simple, that any person, 



Fig. 3, Longitudinal view of a Tunnel. 



Interior. 



^// ^ // / / 

 Entrance. 



Fig. 4.— Application of the Telegraph to Crossings, &c. 

 1 A 2A 



-' — • — ,-.-,-.-,-,^^Hpirap 



•> K 



without any previous acquaintance with it, can send a communication and read the 

 answer." 



The drawings and letter-press description to which we have referred as recently 

 published by Mr. Cooke, furnish (we presume) the further improvements referred 

 to by Professor Wheatstone in the preceding evidence. 



The annexed engravings (Figs. 2 to 11, inclusive,) are reduced copies of the 

 drawings, and subjoined is Mr. Cooke's explanation. 



-Telegraphs for giving Two Signals. 

 D 



Figs. 2 and 3 show the application of the electric telegraph to tunnels. 

 1 A, 2 A. Telegraphs fixed in policemen's boxes near the entrances of 

 tunnels. 



B. Intermediate telegraph near a shaft within a tunnel, always ready to 

 work with 1 A, 2 A, in case of need. 



C. Protecting tube for conducting wires. 



C E, C E. Tube leading to engiue-warner ; vide Figs. 4 and 5 with ex- 

 planation. 



Fig. 4. Application of the electric telegraph to level crossings, approaches 

 to stations, and switches, &c. 



1 A, 2 A, 3 A. Telegraphs fi.ted in policemen's boxes, one or two miles 

 from a level crossing or station. 



C. Protecting tulie for the conducting of telegraph wires, cither carried on 

 posts with a railing over it or under ground. 



D. Telegraphs at stations or level crossings, corresponding with 1A,2A,3A. 

 1 E, 2 E, 3 E. " Engine-warners," (for details vide Figs. 5, 6, 7 and 8,) 



by which an engine gives notice of its approach, at the distance of one or 

 two miles, both to A and D, Fig. 5. If the station or crossing be clear, D 

 replies to the policeman at A to allow the train to " Go on," or else to " Stop," 

 according to circumstances ; the engine-man never venturing to pass A till 

 the policeman has given tlie signal to " Go on." This will ensure the watch- 

 fulness of the policeman ; but even in case of his absence, the conductor 



would inquire by the telegraph A for permission from D to proceed. In the 

 figure, the policemen at 1 A, 2 A, Fig. 4, have received permission from D 

 (as is indicated by the pointing of the handles of the telegraphs at D, corres- 

 ponding with the indications on the telegraph both at D and I A, 2 A,) to 

 allow their respective trains to proceed. The pohceraan notifies in the usual 

 manner, by the white flag, or signal that the line is clear. The train 3 e had 

 been stopped by the policeman at 3 .\, in obedience to a signal from the 

 station D, in reply to the " warning" given by the engine of its approach 

 from 3 E. 



N.B. — The signal given from the " engine-warner " E, at A and D, is 

 " Stop," accompanied by the ringing of an alarum. This signal remains till 

 answered from D. 



Fig. 5. — Telegraphs for giving two signals, as represented above at A, B, 

 and D, each having an alarum (a), which sounds when a signal is given either 

 from E, D, A, or B. . . 



Thirty-one telegraphs, giving two such signals, are working from eight m 

 the morning till ten at night, on the Blackwall Railway, between the stations 

 and the termini, to direct the working of the fixed^engines. 



E represents the details of the " engine-warner." 



An upright bolt passes through one rail of the ■' approaching hne of road, 

 the upper end rising slightlv above the rail, so as to be depressed by an en- 

 gine-wheel, or other very heavy body passing over it. The lower end of the 



