42 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXVIII.) 
hardly at all affected in the time of its vibration, being adjusted so nearly astatic 
as to require about ten seconds to swing to the right or to the left. 
3125. On passing the wire across the magnetic field, as just described (3123.), but 
with different velocities, effects different in degree were obtained at the galvanometer, 
for the reasons formerly given (3104. 3106.). The quickest velocity gave the greatest 
result, equal at times to 140°, whilst a very slow motion gave only 30° or 40°. Still 
with moderately quick velocities the effects were nearly alike, and by operating with 
the same velocity, and taking the average of several observations, a very uniform 
result could be obtained. 
3126. On cutting the wire across, and then putting the ends together in various 
ways, it was found that great care was requisite in making contact, in this or in 
similar cases. Thus, to press the ends lightly together was not sufficient ; they re- 
quired to be well and recently cleaned and pressed closely into contact. Junctions 
effected by soldering or dipping into cups of mercury were still better, when made 
with care, and were employed at the galvanometer and elsewhere as often as 
possible. 
312/. To ascertain generally the obstruction caused by the interposition of thin 
wires, 28 inches of copper wire, 0'045 of an inch in diameter, were introduced into the 
circuit at a part away from the magnet, wdth excellent junctions. The oscillation or 
swing, which before was 140° or more, was now reduced to 40°. On taking out the 
wire and replacing it by another, also of copper, but only 19'5 inches in length, and 
0‘0135 in diameter, the deflection was reduced to 7° or 8°. 
3128. For a rough comparison of the power of this magnet and the former bar 
magnets (3085.), by the present galvanometer, the thick wire was bent into a loop 
(3086.), and the two bar magnets, with like ends together, passed quickly through 
it up to the equatorial part ; the deflection was about 30°. Such a passage intersected 
nearly all the lines of force of the bar magnets. A similar motion of the magnets 
close to, but outside of, the loop, produced no effect at the galvanometer. 
3129. In respect of the alteration of the lines of force, either in position or in total 
amount, by bringing the poles of the horseshoe magnet (3124.) much nearer together, 
the following experiments were made. The distance between the poles is T375 inch ; 
by placing a cube of soft iron, 0'8 of an inch in the side, within this space, it was 
diminished to 0*575, and thus, virtually, the distance apart much lessened, and, as 
was afterwards shown experimentally (3130.), the external power of the magnet con- 
centrated there. Then, whilst the cube was in place, the thick wire of 0*2 of an inch 
in diameter, was arranged so as to pass across the magnetic axis or place of strongest 
action, and fixed ; after which the iron cube was alternately removed and again re- 
stored, and the effects observed. Feeble electric currents were produced at these 
times ; but whether the cube was put into its place from below, or above, or the sides, 
the current produced was always in the same direction; and when it was removed 
the current produced was in the reverse direction. If the cube were carried up to. 
