214 TH & SCIENTIFIC PAPERS Oh' 



quite equal to that obtained in dealing with currents of liquids 

 such as gas or water ; and the time may not be far distant 

 when the use of such an instrument will also become a public 

 necessity. 



Other forms of the instrument will readily suggest themselves 

 to the mind of the constructive engineer ; but the typical form I 

 have described on this occasion will suffice, I think, to show its 

 general character. 



ON THE DYNAMO-ELECTRIC CURRENT, AND ON 

 CERTAIN MEANS TO IMPROVE ITS STEADINESS. 



BY C. WILLIAM SIEMENS, * D.C.L., F.R.S. 



ON the 14th February, 1867, I communicated a short paper to 

 the Royal Society, describing the accumulative or dynamo-electrical 

 principle of action, the conception of which I attributed to my 

 brother Dr. Werner Siemens. When the paper was read, 

 another paper followed by Sir Charles Wheatstone (sent in on 

 the 24th February) also describing this principle of action, thus 

 showing that the same line of thought had occupied that eminent 

 philosopher. 



In illustration of my paper I exhibited a machine of my design, 

 embodying the accumulative principle of action, which furnished 

 abundant evidence of the powerful nature of the current that 

 could be thus produced. It consisted of two horseshoe electro- 

 magnets, between the poles of which a Siemens armature could be 

 made to rotate, the machine being furnished with a handle or 

 pulley for that purpose. A commutator was provided, by which 

 the alternating currents set up in the rotating coil (after a first 

 impulse had been given) were directed through the coils of the 

 stationary electro-magnets in a continuous manner, and proceeded 



* Excerpt Philosophical Transactions of the Royal Society, 1880, pp. 1071- 

 1074. 



