MAGNETO-ELECTRIC INSTRUMENTS. 



Inclosed Magnetic Instruments for F '- 477 - 



Shocks. (Fig. 477.) This instrument 

 consists of an electro-magnet, formed of 

 a bundle of soft iron wires, wound with 

 a double coil of coarse insulated copper 

 wire, over which is wound a coil of fine 

 wire, and inclosed in a cylinder of brass 

 about four inches in diameter and six 

 inches long, supported on a base, and 

 having a cap of mahogany through which 

 the poles of the electro-magnet project, 

 and over which there is one of Page's 

 revolving armatures, supported by a brass 

 pillar and arm, having on one side a small 

 spring pressing the break-piece. The 

 inner coil is connected with the cups on 

 each side of the pillar, and the spring acting on the break- 

 piece, while the fine coil is connected with the cups with 

 binding screws on the opposite side of the cup ; the handles 

 for receiving the shocks are connected with these cups, 

 while the battery current flows through the cups on each side 

 the brass pillar. The shock given with this instrument is 

 quite severe, and does not admit of being reduced as in the 

 preceding instruments. Price, $6.00. 



Saxtoros Magneto- Electric Machine. (Fig. 478, next 

 page.) The magneto-electric machine is one of the most 

 interesting and instructive instruments of modern science ; 

 by it we see exemplified the close connexion between, if not 

 the identity of, the electric and magnetic forces ; by it the 

 same heating, magnetizing, and decomposing power, the 

 same chemical effects, are shown to be common to both. 



A, is a compound horse -shoe magnet, composed of six or 

 more bars, and supported on the rests, b, e, which are screw- 

 ed firmly on the board, B D ; into the rest, e, is screwed 

 the brass pillar, c, carrying the large wheel, /, having a 

 groove in its circumference, and a handle by which it can 

 readily be revolved on its axis ; a spindle passes from one 

 end of the magnet to the other between the poles, and pro- 

 jects beyond them about three inches, where it terminates 

 in a screw at h, to which the armature is attached ; at the 

 further extremity is a small pulley, over which a gut band 



