22 
BRITISH ASSOCIATION.— 1835 . 
from the copper of the battery F along D to c'", along X to c'\ along 
N to R, along T to S, where it enters one pole of the magnet M. 
Now, let the w T ires w rv and w 1 w' have turned a little on their axis 
A B, so as to dip respectively into c' and c"'. The electricity flows 
from F along D to c 111 f along rv w, crossing the axis A B, along K, 
to V, along S, and enters the magnet at N, before it entered at S ; 
hence the current is inverted and the poles reversed. 
The machine can be stopped or set in motion in a moment by lift¬ 
ing or replacing any of the wires forming the galvanic circuit. 
If its motion be interrupted its power is not wasted as in other ma¬ 
chinery, but is accumulating ; so that when it again works, it acts with 
increased power and velocity. We can continue the most perfectly 
uniform motion for any length of time by allowing additional fluid 
to drop very gradually into the copper of the battery; the one cop¬ 
per will answer for any number of magnets. If the zinc plates be 
separate, by insulating these plates with flannel bags we greatly in¬ 
crease the power and add to the duration of the galvanic effect. 
Mr. M’Gauley has endeavoured to examine the relative lifting 
power of magnets of various forms. The following are some of the 
results : 
The Iron . Three helices of the same wire, each 22 feet in length 
were coiled on three different magnets, and the same battery was 
used. 
Magnet No. 1, In length 28 inches, diam. 2 inches, power 
2 . --- 8 ---•§•-—- 
3. A magnet having knobs, B and C each 
1-iV inches in length, diameter 1 inch, 
and connected by an arm -H- by X V, the 
wire coiled on the knobs, with connect¬ 
ing spiral; power - - - 
lb. o z. 
6 8 
11 11 
2 4 
It was found on another occasion that when the helix did not bear 
so great a disproportion to the iron, the power of the larger magnet 
was comparatively very great. To learn the best size for the iron 
bar suspended in the pendulum of the machine, three forms of keeper 
were tried. 
No. 1. 5-1- long, -H- thick, 4 wide ; power. 4 0 
2 . 5 4-4 —— -}"§■ - 3 8 
3. 5-f- —-- -j- 5 - —— x - -- ••••••••♦••• 7 8 
The large magnet would not lift a steel needle, but lifted a wire of 
soft iron equal in size to the needle. Perhaps the intensity of the 
magnetism, though its sum vras nearly equal with the same coil, 
was smaller when diffused through the particles of the larger mag¬ 
net, and was unable to disturb the magnetic equilibrium of the steel 
needle. 
