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Insulated from the framing by suitably formed pieces of 

 ebonite, and also from the shaft, by a cylinder of the same 

 substance. Through the side of the disk, and parallel with 

 its axis, sixteen holes are bored, at equal angular distances 

 from each other, for the reception of the same number of 

 cores or armatures. The cores project about two inches 

 through each side of the disk, and are held firmly in their 

 places by screws tapped through its periphery. Around 

 each inside face of the circular framing, and concentric with 

 the driving shaft, sixteen cylindrical electro-magnets are ^ 

 fixed, at the same angular distance from each other and 

 from the centre of the shaft as the iron cores round the 

 disk ; the two circles of magnets, consequently, have their 

 poles opposite each other, with the disk and its circle of 

 iron cores revolving between them. The ends of the 

 cores are terminated with iron plates of a circular form, 

 which answer the double purpose of retaining the helices 

 surrounding the cores in their places, and overlapping for a 

 short distance the spaces between the poles of the electro- 

 magnets. 



The cylindrical bar magnets are each coiled with 659 feet 

 of copper wire, 0*075 of an inch in diameter, insulated with 

 cotton. The helices are grouped together to form a fourfold 

 circuit, 2,636 feet in length, and are joined up in such a 

 manner that adjacent magnets in each circle, as well as those 

 directly opposite in both circles, have north and south 

 polarity in relation to each other. A charge of permanent 

 magnetism was imparted to the system of electro-magnets 

 by the current from a separate electro-magnetic machine. 

 The armatures, although formed of sixteen pieces of iron, 

 are, by projecting through both sides of the disk, thirty-two 

 in number. The length of insulated wire on each armature 

 is 116 feet, and the thickness is the same as that on the 

 electro-magnets. These helices are divided into eight groups 

 of four each, and coupled up for an intensity of 4 x 116 feet. 



