312 ROUGH WAYS MADE SMOOTH. 



more cheaply here than in America. Nay, it has even been 

 found advantageous in some cases to use a gas engine to 

 generate electricity. Thus Mr. Van der Weyde used an 

 Otto gas engine driven at the cost of 6d. an hour for gas, 

 to produce the light which he exhibited publicly on the 

 night of November 9. So that the cheapness of gas may 

 make the electric light cheaper. Then it is to be remem- 

 bered that important though the question of cost is, it is far 

 from being all-important. The advantages of electric light- 

 ing for many purposes, as in public libraries, in cases where 

 many persons work together under conditions rendering 

 the vitiation of the air by gas lighting exceedingly mis- 

 chievous, and in cases where the recognition of delicate 

 differences of tint or texture is essential, must far more 

 than compensate for some slight difference in cost. The 

 possibility (shown by actual experience to be real) of 

 employing natural sources of power to drive machines for 

 generating electricity, is another interesting element of the 

 subject, but could not be properly dealt with save in greater 

 space than this here available. 



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