23S 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[July 



Fig. 1.— Original Eicctric Te\egr,iph. 



Fig. 2, Perspective view of a Tunnel. 



1 i 1 



discontinues to ring. There are several other contri- 

 vances made to effect this purpose. Some other 

 arrangements there are to which Mr. Cooke has 

 particularly directed his attention, relating to the 

 means of establishing communications at interme- 

 diate parts of the line where no fixed stations exist. 

 To effect this, posts are placed at every quarter of 

 a mile along the line, for the purpose of establish- 

 ing a temporary communication with either of the 

 adjacent stations; the guard of a train may thus 

 carry with him a portable instrument, by means of 

 which he can send up a message to a station either 

 way, whenever it may be required. The w ires are 

 kept insulated from each other by a mixture of 

 cotton and india rubber, which is a very good insu- 

 lating material ; then these prepared wires are all 

 passed, with certain precautions, through an iron 

 tube, which in some parts of the line is buried be- 

 neath the ground, and in other parts of the line is 

 raised above it." 



Lord Granville Somerset put this case : — " Sup- 

 pose the Great Western Railway were completed 

 between London and Bristol, do you contemplate 

 the possibility of carrying your telegraph through 

 the whole way, so as to signify from London to 

 Bristol any thing you wish to communicate, and vice 

 versa from Bristol to London?" — Professor Wheat- 

 stone replied, "The experiment has not been tried, 

 but I have every reason to believe that it can be 

 done. One very important circumstance I have 

 ascertained is the little power requisite to produce 

 this effect ; it was formerly thought, that to send a 

 current to any considerable extent very strong bat- 

 teries must be employed, but in fact a very weak 

 battery is sufficient, provided only it consist of a 

 number of elements proportionate to the distance. 

 So far as my experiments have gone, I think I 

 should be able to effect a telegraphic communication 

 between Bristol and London. Possibly several sta- 

 tions might be required, but, at any rate, the sta- 

 tions may be at far greater distances from each 

 other than would be required for any ordinary sys- 

 tem of telegraphs ; my opinion is, that the inter- 

 mediate stations will not be required." 



Mr. Loch asked whether there was any appre- 

 ciable loss of time in making a communication from 

 the Paddington station to the extremity of the line 

 to which the telegraph is now carried ? Professor 

 Wheatstone: "From some experiments I made 

 some years ago, published in the Philosophical 

 Transactions, when I first turned my attention to 

 the possibility of effecting telegraphic communica- 

 tions, I ascertained that electricity travelled through 

 a copper wire at the rate of about 200,UU0 miles in 

 a second ; consequently there is no appreciable 

 time lost in the communication of the electrical 

 effect ; the only time that would be lost would be at 

 relay stations, if they were necessary." 



Chairman: "Could you communicate from Dover 

 to Calais in that way ? — I think it perfectly prac- 

 ticable." 



Professor W. added the following observations: 



" An electrical telegraph offers a great many ad- 

 vantages over an ordinary telegraph ; it will work 

 day and night, but an ordinary telegraph will act 

 only during day; it will also work in all states of 

 weather, an ordinary telegraph can only work in 

 fine weather. There are a great number of days 

 in the year in which no communication can be 

 given bv an ordinary telegraph, and besides, a great 

 many communications are stopped before they can 

 be finished, on account of changes in the state of 

 the atmosphere. No inconveniences of this kind 

 would attend the electrical telegraph. Another 

 advantage is, that the expense of the separate sta- 

 tions is by no means comparable to that of the or- 

 dinary telegraph ; no look-out men are required, 

 and the apparatus may be worked in any room 

 where there are persons to attend to it. There is 

 another advantage the electric possesses over the 



