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Notice of a New Signal-Light for Raihvays. By Alan Ste- 

 venson, LL.B. Civil Engineer, Edinburgh. Communicated 

 by the Society of Arts for Scotland.* 



The numerous accidents attended with fatal consequences 

 which have lately occurred on railways have excited much 

 alarm in the public mind, and the prevention of these casual- 

 ties is unquestionably a matter of great importance. The ob- 

 ject of this communication is, to point out one source of dan- 

 ger to which several of the late accidents may be attributed, 

 and to suggest the means of its removal ; and from the per- 

 sonal interest which all must have in the improvement of rail- 

 way-travelling, both as regards its speed and, what is of much 

 greater importance, its safety, I venture to hope that the 

 following observations, although limited to one part of the 

 subject, will not be found to have been unsuitably addressed 

 to a society whose province it is to improve the useful arts. 



One of the most imperfect parts of the railway system is 

 undoubtedly the uncertainty of the night signals, and to this 

 it is well known many of the most fatal of the accidents which 

 have occurred must be traced. The great object of these sig- 

 nal-lights is, to announce that the train has reached a certain 

 point of its course, and to forewarn the engineman of his 

 approach to a station, or the junction of a branch railway, so 

 that the speed of the engine may be checked in proper time 

 to prevent collision. The lights used for this purpose are ge- 

 nerally exhibited at the place the approach to which they are 

 intended to announce ; but the distance at which light projected 

 horizontally, may be seen by a person approaching in the line 

 of its transmission is very variable according to the state of 

 the atmosphere, which in our climate is subject to great and 

 sudden changes, in regard to clearness and fog. These va- 

 riations in the visibility of lights of extensive range are by no 

 means confined within narrow limits, as experience too amply 

 demonstrates in the case of lighthouses, whose range has been 

 known to vary with the state of the atmosphere, from sixty 



* Read before the Society of Arts for Scotland, 22d February 1841. 



