172 MR. FARADAY’S EXPERIMENTAL RESEx\RCHES IN ELECTRICITY. 
rent always being conformable to the law formerly expressed (114.), and also 
to the directions obtained with the rotating ball (164.). 
1/4. In these experiments it is not necessary to move the galvanometer or 
needle from its first position. It is quite sufficient if the wire of the rectangle 
is distorted where it leaves the instrument, and bent so as to allow the moving 
upper part to travel in the desired direction. 
1/5. The moveable part of the wire was then arranged below the galvano¬ 
meter, but so as to be carried across the dip. It affected the instrument as 
before, and in the same direction ; i. e. when carried from west to east under 
the instrument, the marked end of the needle went west, as before. This 
should, of course, be the case; for when the wire is cutting the magnetic dip 
in a certain direction, an electric current also in a certain direction should be 
induced in it. 
176. If in fig. 31. dp be parallel to the dip, and B A be considered as the 
upper part of the rectangle (1/1.), with an arrow c attached to it, both these 
being retained in a plane perpendicular to the dip, — then, however B A with its 
attached arrow is moved upon dp as an axis, if it afterwards proceed in the 
direction of the arrow, a current of electricity will move along it from B to¬ 
wards A. 
1/7- When the moving part of the wire was carried up or down parallel to 
the dip, no effect was produced on the galvanometer. When the direction of 
motion was a little inclined to the dip, electricity manifested itself; and was 
at a maximum when the motion was perpendicular to the magnetic direction. 
17S. When the wire was bent into other forms and moved, equally strong 
effects were obtained, especially when instead of a rectangle a double cate¬ 
narian curve was formed of it on one side of the galvanometer, and the two 
single curves or halves were swung in opposite directions at the same time; 
their action then combined to affect the galvanometer: but all the results were 
reducible to those above described. 
179. The longer the extent of the moving wire, and the greater the space 
through which it moves, the greater is the effect upon the galvanometer. 
180. The facility with which electric currents are produced in metals when 
moving under the influence of magnets, suggests that henceforth precautions 
should always be taken, in experiments upon metals and magnets, to guard 
