Description of a Magnetic Electrical Machine. 215 
hollow cylinder K at one end, and held in metallic contact by a 
nurled head screw in the brass strap M, which is fixed to the side 
of the wooden block L. P and P, a square brass pillar, fitting into 
@ square opening in the other brass strap N, and secured at any con- 
venient height required. Q and Q, a metal spring that rubs gently 
on the break-piece H, and held in perfect metallic contact by the 
nurled head screw in P. T and T, a piece of copper wire for con- 
necting the two brass straps, M, N; then D, H, Q, P, N, are in 
connexion with the commencement of each coil, and K, O, M, with 
the terminations. ‘The advantages of this arrangement must be ob- 
vious to any person who has seen the magnetic machine in action in 
the Adelaide Gallery of Practical Science, where the old. arrange- 
ment of the mercury flood is still used, where both disc and blades 
scatter the mercury about as in fig. 1’: a, the disc; 6, the double 
blades; c, the mercury flood. The loss of mer- 
cury is not the only evil; for as you continue FIG. 1. 
working the machine, you of course, lose the 
adjustment you had at starting, and the effect is 
constantly diminishing, and will at length cease, 
owing to the points 6 not having mercury to 
dip in. By the new arrangement, the metal 
spring Q presses gently on the break H; con- 
sequently, the effects here are unbroken, no 
matter how long you may require to keep the 
machine acting. ‘This is not the only advantage it possesses; for in 
the mercury the surface is very rapidly oxidated ; the oxide adheres 
to both disc and point, and preventing so perfect a metallic contact 
as that obtained by the spring and break. 
To adjust the intensity armature. 
See that the faces of the iron cylinders that carry the coils F, G, 
fig. 1, are parallel to, and all but in contact with, the magnetic bat- 
tery A; if not, unscrew the nut of the multiplying wheel E, and 
take it off its axis: you then have at your command the four screws 
against which the battery rests, (two of which are to be seen at MN, 
fig. 12;) by means of them and the nut of the strap C, you can ad- 
just the battery to the greatest nicety. ‘The next step is to adjust 
the break, so that the spring Q will separate from it just at the same 
time that the iron cylinders of the armature have left the poles of 
the magnetic battery ; and lastly, see that the iron wire spring O, 
presses gently against the hollow brass cylinder K. 
