126 An account of the Electro-Magnetic Engine. 



ed is, that the stationary circle of magnets of the former is supplied by 

 one of electro-magnets in this, and the external circle of soft iron di- 

 vided into two to form the poles. These semicircles are one-eighth of 

 an inch thick, one inch broad, encircled in copper wire, and isolated by 

 cotton. This wire extends over about ten inches of each circle ; and, 

 by being coiled back upon itself, presents two shafts of wire, amount- 

 ing on both semicircles to about 1500 inches. 



The iron of the semicircles is not entirely encircled, but the ends are 

 left naked and bent inwards, as represented in figure 5 : each of the 

 ends bent in is about one-sixth of the semicirele. The semicircles thus 

 formed may, if desired, be converted into electro-magnets, and are sub- 

 stituted in the place of permanent steel magnets in the former machine. 

 In order to obviate the necessity of having two batteries, the conduct- 

 ing wires are so arranged that the same current which supplies the 

 magnets of the fly-wheel, also supply the stationary magnets which 

 surround it. The stationary galvanic magnets by which the place of 

 the steel magnets is supplied, are only half as heavy as the former. 

 With a battery which could be immersed in a quart of diluted acid, the 

 apparatus raised 16lbs. very rapidly ; and, without the weight, exe- 

 cuted 600 evolutions in a minute. The machine was so sensitive of 

 magnetic power that it went with considerable speed when the battery 

 was sunk but an inch deep into the acid. When provided with electro- 

 magnets the effect seemed more powerful than with the ordinary mag- 

 nets. 



We are indebted for a great improvement in electro-magnetic 

 machines to the mechanician Stoehrer, of Leipsic, who has constructed 

 a machine as a model, the perfect simplicity and easy construction 

 of which will in all probability insure its application in the room of all 

 other moving powers. It is worked at present but by four elements, 

 each consisting of a copper cylinder filled with vitriolic acid in which a 

 zinc plate is hung, and sets a lathe in motion, which is applied to the 

 turning of small brass articles. The expense of this power for twenty- 

 four hours is one shilling, one-half of which is fully covered by the 

 pure metallic copper which is obtained. 



Stoehrer constructed his model last year on the principles laid down 

 by Jacobi; and some time after, Wagener, of Frankfort, constructed a 

 similar model, for which a reward of 100,000 florins was guaranteed 

 him by the German Diet, as soon as the plan should be carried out 

 on a large scale. 



This execution on a large scale has, according to the latest accounts, 

 succeeded most brilliantly ; for a saw-mill is at present worked by 



