RESEARCHES IN MAGNETISM. 
581 
The magnetometer stood on the top of a solid stone pier, which rose, clear of the floor, 
to a height of about 3 feet above the floor. To the top of it, and on the two sides of 
the magnetometer, two stout brackets, a a, were very rigidly fixed. To these a pair of 
brass plates with \/ notches cut in them were secured, which served to carry a cross 
piece, b, consisting of a cylinder of brass. This cylinder was prevented from moving 
in the direction of its own length by an end plate, c. The iron wire under examination, 
d, had brazed to it at its upper end a short piece of thicker brass wire which was 
rivetted into the middle of the cylinder, b. At the bottom of d a copper wire e was 
attached on which the lead weights were strung. 
In some of the experiments the vertical component of the earth’s magnetic field 
MDC CCLXXXY. 4 F 
