1865.] Tyler on Circulation and Communication on Hallways. 585 



than was prudent. If a train became divided, the engine-driver ought 

 to be informed of the circumstance at once, as well as the guards, in 

 order that he might act for the best, according to the locality, the 

 speed at which he was travelling, and the gradients of the line. If on 

 an alarm being given no external sign were observed of anything 

 wrong, then it would be the duty of the engine-driver and guards, in 

 the absence of any means of circulation, to bring the train to a stand 

 at the nearest convenient and safe point, say under the protection of 

 the first fixed signals. Where the power of circulation existed, the 

 nearest guard would at once repair to the carriage whence such an 

 alarm had been given. 



In order effectually to carry out this system, it is necessary that a 

 means should be provided of ringing a bell, or otherwise calling atten- 

 tion, in every break- van in a train and on the engine ; and to render 

 it perfect, it is desirable that each guard should be able to send 

 a signal to, or receive one from, the engine-driver at any moment. It 

 is further necessary, in the interest of the travelling public, as well as 

 in that of the railway companies, that there should be a certain means 

 of detecting the compartment from which a signal has been given. 

 The methods proposed for effecting communication have been very 

 numerous. They cannot here be enumerated in detail, but they may 

 be divided as follows into a few classes : — 



1. Sound signals, such r.s bells, gongs, firearms, or detonators 

 affixed to the different carriages, connected or not with outside flags, 

 discs, or arms to attract attention to the part of the train whence the 

 sound proceeds. Gong signals of this sort were lately fitted up and 

 tested experimentally by Mr. Edmund Tattersall on the London and 

 South- Western Eailway. 



Such signals, requiring no extra coupling between the carriages, 

 would be admirable if they could be made efficient. But, unfortunately, 

 there is no certainty of their being heard, even from front to rear, in a 

 long train ; and they are frequently inaudible, under the most favour- 

 able conditions, when a train is travelling at high speed, towards the 

 front. The rattle of a train, in passing particularly through cuttings, 

 or tunnels, or bridges, is so great as sometimes to render the steam 

 whistle of the engine inaudible to the guard in his van. 



On this point the Clearing House Sub-committee of 1853 observe : 

 — " 29. The remarks made in a former part of this report, when treat- 

 ing of air whistles, prove that signals depending on sound, if made 

 at a distance from the engine-driver, are as little to be relied on as 

 those depending on sight. Several members of the committee have at 

 various times conducted experiments having sound for their basis ; and 

 the result has invariably been that no noise, however loud, shrill, or 

 continued, whether the sound was produced by compressed air, trum- 

 pets, or gunpowder, could be heard, even when the train was short, 

 when there was a head wind, or when the speed of the train was con- 

 siderable." 



Of this class, also, those which depend upon gunpowder, or explo- 

 sive compositions, would be liable, after lying ready, perhaps, for 

 years, to fail when they were required for use. 



