1893.] on Theory and Practice in Electrical Science. 83 



principle by the consideration that an electro-magnetic machine 

 behaved like a magneto-electric machine, when a current of electricity 

 was sent into it, viz. both turn round and give out power. It was, 

 of course, well known that a magneto-electric machine produces a 

 current of electricity when turned by mechanical power, and Werner 

 concluded that an electro-magnetic machine would behave in the 

 same manner. We all know that he was right, but I relate this 

 circumstance only as a further proof that the generation of power by 

 electric currents had been a well-known fact long previous to the 

 Vienna Exhibition. 



Another well-known instance of transmission of power to a 

 distance is furnished by the magneto-electric ABC telegraph 

 instruments, where the motion at the sending end supplies the 

 currents necessary to move the indicator at the receiving station. 



As an illustration of the distribution of power by electricity I will 

 briefly describe some radical alterations that have been made at the 

 works of Messrs. Siemens Brothers and Co. by the introduction of 

 electric motors in the place of steam engines. The diagram on the 

 wall shows in outline the various buildings in which work of different 

 kinds is carried on with the help of different machines. Electric 

 motors are supplying the power, sometimes by driving shafting to 

 which a group of tools is connected by belting, and sometimes by 

 being coupled direct to the moving mechanism. Each section of the 

 works has its own meter measuring the energy that is used there, and 

 all of them are connected by underground cables to a central station, 

 where three sets of engines and dynamos generate the electric current 

 for all purposes. 



There are two Willans and one Belliss steam engines, each of 

 300 I.H.P., coupled direct to the dynamos and running at a speed 

 of 350 revolutions per minute. 



Eoom is left for a fourth set ; but, including some auxiliary pumps 

 and the switchboards for controlling the dynamos and for distributing 

 the current, the whole space occupied by 1200 horse-power measures 

 only 32 by 42 feet. 



Close by are the condensers and three high-pressure boilers, 

 which have replaced some low-pressure ones formerly used for some 

 steam engines driving the machinery in the nearest building. 



The advantages that have been secured by the introduction of 

 electric motors may be briefly stated under the following heads : — 



1. Various valuable spaces formerly occupied by steam engines 

 and boilers have been made available for the extension of workshops, 

 and these are indicated on the diagram by shading. 



2. By abolishing to a great extent the mechanical transmission 

 of power a considerable saving is effected in motive power, which 

 is especially noticeable at times when part only of the machinery is 

 in use. 



3. As the electric motors take only as much current as is actually 

 required for the work they are doing, a further saving is effected and 



Vol. XIV. (No. 87.) d 



