GENERAL CHARACTER. 679 



PART IV. 

 COMPLEMENT. 



CHAPTER I. 

 INDUSTRIAL APPLICATIONS. 



1239. GENERAL CHARACTER. The numerous applications to 

 which electricity gives rise may be classed in different groups. 



The shocks produced by electric sparks were the starting point 

 for what is now a very extended branch of science, electro- 

 physiology, which comprises the effects of electricity on living 

 beings, and the investigation of the electromotive forces of which 

 their organs are the seat. 



In another series of applications use is made of the rapidity 

 with which electrical phenomena are propagated in a conductor. 

 The work . of currents is sometimes directly utilised to produce a 

 mechanical effect at a distance, as in bell work and direct tele- 

 graphs; but most frequently the electricity only serves to produce 

 a signal, or by a sort of detachment sets to work other mechanical 

 forces, such as the action of a weight, a spring, or of a local 

 battery; such are most of the telegraphs, registering instruments, 

 microphones, etc. In all cases the work, and the expense of the 

 electrical energy utilised, are of no great importance; all the pro- 

 gress to be realised in this kind of apparatus lies in the rapidity 

 of the signals and the certainty with which the various parts 

 work. 



We shall restrict ourselves to those applications in which it 

 is especially proposed to utilise the electrical energy itself, as in 

 galvanoplastics, lighting, or the transmission of force. In these 

 different cases, we are concerned with the amount of work utilised 

 and its economical efficiency. 



