520 Mr. G. Gore on the Rotation of Metallic Tubes 



the motion imparted to it, provided the resistances to its motion 

 are sufficiently small and uniform ; or if the resistances are not 

 uniform, it will continue to vibrate or roll backwards and forwards 

 as long as the electric current is passing. 



This effect I have obtained in several ways by forming the 

 cylinder of various metals, of different diameters, lengths and 

 weights; and the rails of various metals, thin sheet, plate, and 

 .stretched wire of different thicknesses, with various degrees of 

 success. Upon the small scale I have obtained the backward 

 and forward motion thus : — Two thin strips of brass, | an inch 

 wide and 10 inches long, were affixed parallel to each other upon 

 the opposite sides of a bar of wood about 3 inches wide ; their 

 edges rising one-eighth of an inch above the surface of the wood 

 and forming two metallic rails. A thin zinc tube, 3i inches 

 long and 2 inches diameter, weighing about 300 grains, was 

 placed upon the rails, and the latter connected with two pairs of 

 Smee's battery, strongly charged, and containing single plates 

 of zinc and platinized silver, 8 inches by 10 inches. 



To obtain a continuous rolling motion in one uniform direc- 

 tion, I have constructed the following apparatus (see figures) : — 

 A is a circular base of wood provided with two brass rails or 

 hoops, B and C, about ^jth of an inch thick ; level, uniform, 

 and equidistant, and metallically connected with the screws D 

 and E ; the outer one is a quarter of an inch higher than the 

 other. F is a thin copper ball, hollow, of uniform thickness, 

 weighing about 500 grains, and as round as it can be made. 



The base having been set perfectly level, the screws D and E 

 connected with a suitable battery, i. e. one yielding a current of 

 copious quantity and moderate intensity*, and the ball placed 

 upon the rails, the ball immediately began to vibrate, and in- 

 creased its motion until complete rotation and revolution was 

 obtained; and it continued to revolve in either direction with 

 equal facility as long as the current was passing. The ball also 

 at the same time became much heated. f 



As some difficulty may be experienced in obtaining a suitable 

 ball, the following particulars are given : — A thick ring of brass 

 was turned in a lathe to an internal diameter the same as that 

 of the ball ; it was then divided into two equal parts, and one of 

 them used as a pattern from which to form in a lathe a hemi- 

 spherical " chuck " of hard and dry wood ; a disc of thin copper 

 was then placed against the wood and formed into a cup by the 



* Three zinc and carbon batteries, with zinc cylinders 6 inches high 

 and 3^ inches diameter, strongly charged with dihite sulphuric and strong 

 nitric acids, and connected together as one pair, propelled the ball at a rate 

 of sixteen revolutions i)er minute. 



t Experiments exhibited before the Royal Society, June 3, 1858. 



