ELECTRICAL APPARATUS. 



283 



the pillars. On these wires the axis of the fly rests, the 

 ends of which are formed like a small pulley, having a 

 groove in them to prevent their slipping off the wires, and 

 to guide the fly when in action. It is obvious that if the fly 

 be placed on the upper part of the wires, it will roll down 

 them by its own gravity ; but when it has reached the 

 bottom of the plane, if the upper end of the wires be con- 

 nected with the machine while in action, the escape of the 

 fluids from the points will cause it to roll very rapidly up 

 the plane till it reach the top of it. 



These experiments may be varied to a great extent, and 

 models of corn-mills, water-pumps, astronomical clocks, etc., 

 constructed of cork and pasteboard, are readily put in action 

 by directing against their main wheels a stream of electricity 

 from a strong pointed wire inserted into the prime con- 

 ductor. Price, $3.00. 



Fig. 318 



The Electrical Sportsman. (Fig. 318, as above.) Tin's 

 experiment is to illustrate the fact that a jar will be liable to 

 discharge itself when the two coatings are too close to each 

 other. The inner coating of the Leyden jar is connected 

 with two wires, one of which proceeds to the birds the 

 other proceeds to within a short distance of the muzzle of 

 the gun. The birds are made of small bits of pith, with a 

 portion of feathers to each, to represent wings. They are 

 attached to pieces of linen thread, four or five inches long. 

 The gun is connected with the outer coating of the wire pro- 

 ceeding from it to the figure, and a slip of tin-foil which is 



