1S2 



ElecLro-J\[ag-)ielic Motors, 



[Jan. 



the poiulerous, expensive and dangerous machinery of steam, rivalled 

 by the light, economical and harmless engines which electro-magne- 

 tism will place at our command." Mr. M'Ganley also has made re- 

 ports on this subject to the meetings of the British Association held at 

 Dublin and Bristol. The mechanical apparatus contrived by the 

 different experimentalists vary considerably. We have selected the 

 following from the Magazine of Popular Science, as it offers a concise 

 and simple view of the principles of the subject.—EDiToR Madras 

 J ournalJ] 



Professor Silliman having been invited to examine, and report upoiiy 

 an Electro-magnetic Machine, invented by Mr. Thomas Davenport, of 

 Brandon, near Rutland, Vermont, gave the subject his attention m 

 Marcli last, and inserted the following description in the number of his 

 Journal which was published in April. 



The Machine was exhibited by means of a working-model, in two 

 varieties of form, viz. — 



I. The Rotary Macldne, composed of revolving Electro-magnets, with 

 Jisced permanent Magnets. 



The moving part is composed of two iron bars placed horizontally, 

 and crossing each other at right angles. They are both five and a half 

 inches long, and they are terminated at each end by a segment of a 

 circle made of soft iron ; these segments are each three inches long in 

 the chord line, and their position, as they are suspended upon the ends 

 of the iron bars, is horizontal. 



This iron cross is sustained by a vertical axis, standing wdth its pivot 

 in a socket, and admitting of easy rotation. The iron cross bars are 

 wound with copper wire, covered by cotton, and they are made to form, 

 at pleasure, a proper connexion with a small circular battery, made of 

 concentric cylinders of copper and zinc, which can be immersed in a 

 quart of acidulated water. Two semicircles of strongly magnetized 

 steel form an entire circle, interrupted only at the two opposite poles, 

 and within this circle,which lies horizontally, the galvanized iron cross 

 moves in such a manner that its iron segments revolve parallel and 

 very near to the magnetic circle, and in the same plane. Its axis at its 

 upper end, is fitted by a horizontal cog-wheel to another and larger 

 vertical wheel, to whose horizontal axis weight is attached, and raised 

 by the winding of a rope. As soon as the small battery, destined to 

 generate the power, is properly connected with the machine, and duly 

 excited by diluted acid, the motion begins, by the horizontal movement 



