100 Electric Lighting. 



wet weather. A person coming in contact with the 

 wires or any portion of the apparatus might, and 

 probably would, detect the presence of a current, but 

 that is all ; so that for safety and facility for conducting the 

 current, the low tension was all that could be desired. But 

 then it became clear that if a considerable distance inter- 

 vened between the lamp and the machine, a very large con- 

 ductor became necessary, whilst if more than one light was 

 required on one circuit, the low tension current failed to 

 support them. Consequently the tension of the current was 

 increased in proportion to the number of lights required to 

 be maintained, or for the distance the current had to pass 

 between the machine and lamp, and attended with the usual 

 characteristics of currents of this nature. 



The insulation of everything in connection with the cir- 

 cuit has to be most carefully attended to ; and such insula- 

 tion requires to be of a very high nature, or failures must 

 occur. The recent failures of the Brush system in London, 

 Edinburgh, and elsewhere, have all been traced to imperfect 

 insulation of the circuit, and if it has been found difficult 

 and expensive to provide a perfect insulation for a current 

 supporting from 30 to 40 lights, those who are familiar with 

 the behaviour of high tension currents will at once realise 

 the state of affairs, if machines were made to support, say, 

 even 100 ; and with the difficulties of insulation comes the 

 dangers from fire, and loss of human life. With a badly 

 insulated conductor from such machines, fires have occurred 

 undoubtedly ; whilst there have also been several instances 

 recorded of fatal accidents occurring through the same cause, 

 and although, by taking careful precautions, the risks of 

 mishaps may be reduced to a minimum, they are always 

 liable to occur, and with any increase in the tension of the 

 current, probably would constantly occur. It would there- 

 fore appear that machines capable of supporting, say, from 

 ten to fifteen powerful arc lights, are the largest that should 

 be used, both for safety and certainty in working, as long as 

 high-tension currents are required for such purpose. This 

 would therefore point to the conclusion, that, for successful 

 and commercial electric lighting, we should look in another 

 direction, even if we have to re-arrange the whole of our 

 present system of working. 



Since writing this I have come across a paper read by 

 Mr. Swan, before the Royal Institution, and printed in 

 Engineering for March, and in which the following para- 



