WINTER'S ELECTRICAL MACHINE. 593 



so mounted that a body of glass or ebonite revolving on 

 an axis may be easily and rapidly moved against it; a 

 row of points attached to a brass rod collects the elec- 

 tricity produced in the revolving body, and communi- 

 cates it to the ' conductor/ a body with a metallic 

 surface on which the electricity accumulates. 



Fig. 315 shows the arrangement of these parts in a 

 machine known as ' Winter's electrical machine.' A 

 stout circular glass-plate, g g, is supported between two 

 pillars, 1 1, by an axis, a a, of glass passing through the 

 centre, which is turned by means of the handle k in 

 the direction of the arrow. The plate revolves between 

 two rubbers which are placed in a wooden frame r, on 

 each side of it. The edges and corners of the frame 

 are rounded off, and it is insulated upon a pillar of 

 glass. Attached to the wood of the frame is a sphere 

 of metal, from which, on approaching the finger, sparks 

 of the negative electricity generated in the rubbers 

 may be drawn. The conductor c is a hollow sphere of 

 brass, the interior of which is exactly like that shown 

 in fig. 312. The stalk of a small brass ball fits into 

 the left horizontal opening, while the right opening 

 serves for the attachment of the collecting apparatus s s, 

 which consists of rows of points, placed inside of two 

 wooden rings in grooves; the rings are connected to- 

 gether and with the conductor by a bent piece of brass. 

 To prevent the electricity of the plate from discharging 

 itself into the air before reaching the prime conductor, 

 each rubber has a non-conducting wing of silk fastened 

 to it. When the machine is in action, electrical attrac- 

 tion makes them adhere to the plate. 



QQ 



