by a Spark from a small Magnet. \05 



hydrogen, thus establishing for the first time one of the phy- 

 sical properties of the magneto-electric spark*. As the ex- 

 periment is thus rendered what may be called a good class- 

 experiment, and as the account of it has only been partially 

 published, I have ventured to request you to give it a place 

 in the Philosophical Magazine. 



I am, Gentlemen, yours, &c. 



William Ritchie. 



Take a short lifter, either round or square, of the worst En- 

 glish iron, a little shorter than the whole length across the 

 poles of a horse-shoe magnet capable of carrying fifteen or 

 twenty pounds, and roll a ribbon of fine copper round the 

 middle of it, metallic contact being prevented by a thin tape 

 interposed between the spirals. The length of the copper 

 ribbon may be about ten or twelve feet. To the ends of the 

 coil two thick copper wires are to be soldered, in order to 

 form a complete metallic circuit when the lifter is in contact 

 with the poles of the magnet. The magnet is mounted on a 

 base or sole of wood, having a pillar with an arm or lever 

 passing through a mortice in the top of it for the purpose of 

 removing, by a sudden jerk, the lifter from the poles of the 

 magnet. 



The description will be best understood by reference to the 

 annexed figure, in which 

 A B is the lifter of soft 

 iron, D E the lever for 

 the purpose of suddenly 

 raising the lifter by a smart 

 blow given with the palm 

 of the hand at E. In front 

 of the magnet a glass tube 

 G, is placed, having its 

 top closed by a cap of box- 

 wood, with a hole in the 

 centre, to allow one of 

 the copper wires to pass 

 through it. The other 

 wire or end of the coil is 

 made to play up and 

 down in a brass tube filled 

 with mercury. This tube has a thick copper wire soldered 



* The readers of your Journal are perfectly aware that Mr. Faraday 

 first obtained the spark from a temporary electro-magnet, and after his 

 researches had found their way to Italy, SS. Nobili and Antinori obtained 

 it from a permanent magnet. [See Phil. Mag. and Annals, N.S. vol. xi. 

 p. 401.— Edit.] 



Third Series. Vol. 4. No. 20. Feb. 1834. P 



