294 LIGHT SCIENCE FOR LEISURE HQURS. 



of ^collisions at sea, though it is one about which much 

 might be said. But such disastrous collisions as have 

 occurred recently might easily be avoided, or at least 

 rendered extremely infrequent, if proper means were 

 used for indicating, by strong lights suitably placed, 

 the position of steamships, whether in motion or at 

 rest. Everyone who has traversed a thick fog, even a 

 London fog, since the electric light has been much 

 used in towns, knows how much farther a strong 

 electric light shows in a fog than the best gas-light, 

 and (still more) than any oil-light. It is well-known, 

 too, how much the use of any coloured glass diminishes 

 the range of distance through which a light can be 

 seen. Now, it may very well be that the general use 

 of the electric light on board steamships may not be 

 possible at present. I should have thought the owners 

 of our best ocean steamships would long since have 

 decided to use only the electric light for their signal- 

 lamps, if not for illuminating purposes throughout 

 those ships. But supposing this not yet possible or 

 convenient, it is yet obvious that in every steamship, 

 either slowed or brought to rest during fog, there is 

 available a store of energy which might be well em- 

 ployed at those critical times to drive a dynamo 

 machine and maintain any desired number of very 

 strong electric lights in suitable positions. Such lights 

 would penetrate to a considerable distance through any 

 ordinary sea fog. If they had been burning on the ' City 

 of Brussels ' and the Kirby Hall,' or on the ' Cimbria * 

 and ' Sultan,' it is, to all intents and purposes, certain 



