?us Magnetic Electrical Machine. 263 



Fig. \. aa', the magnetic battery, resting against four ad- 

 justing screws, which pass through the mahogany back-board 

 bi c, a strap of brass, having an opening in the middle, 

 through which a bolt and nut pass that are fixed in the board 

 b ; d and d', fig. 2, two soft-iron armatures, screwing into a 

 brass mandril, which is seated between the poles of a a', ro- 

 tatory motion being communicated to it by a band passing'over 

 tlie mandril, pulley, and the mahogany multiplying wheel e; 

 fj, fig. 1, and /'/', fig. 2, coils of insulated copper wire, the 

 commencement of each coil being in metallic connexion with 

 the break g, and the terminations of each in connexion with 

 the hollow brass cylinder z ; i, a closed box to contain mer- 

 cury, the connexion being made with the commencement of 

 the coils //and /'/', by the copper hook /r, one end of which 

 rests on the break, the other end screwing through the top of 

 the box i into the flood of mercury which it contains ; /, a spi- 

 ral spring of steel wire, one end dipping into the mercury in 

 the box /, the other end rubbing on the hollow cylinder z. 



Fig. 3. An apparatus to show the decomposition of water 

 by magnetic electricity, for a description of which see my paper 

 in the number of your Magazine for June 1835(vol. vi. p. 427), 

 but differing in as much as the gases are here collected mixed 

 in one tube. 



Fig. 4. An apparatus to show the ignition of platina wire 

 by magnetic electricity ; aa',b b', two pieces of insulated cop- 

 per wire twisted together ; c, a piece of very fine platina wire 

 soldered to a b. 



Fig. 5. A piece of soft iron bent in the shape of a horseshoe 

 magnet, having two coils of insulated copper wire, and an 

 iron keeper to show that magnetic electricity induces mao-net- 

 ism on soft iron. ^ 



The advantages of these arrangements are as follows : 



First. That I am enabled to give motion to my armatures 

 without communicating any vibration to my magnetic battery, 

 which I know by experience to be highly injurious to either 

 bent or straight bar magnets. 



Second. As my magnetic battery stands perfectly indepen- 

 dent of the armatures, and also of the machinery which gives 

 them motion, every facility is afforded of withdrawing the bat- 

 tery from the machine, so that it may be applied to any other 

 purpose where powerful magnets are required. 



Third. Having in November, 1834, tried the effects pro- 

 duced by coils of wire varying in diameter, I found that the 

 thick copper bell-wire gave brilliant sparks, but no perceptible 

 shock, whilst, on the contrary, very fine wire gave powerful 

 shocks, but very indifferent sparks. I took advantage of my 



