MAGNETIC CHARACTERS OF METALS, &c. 64] 
Besides the sliding door which closes one side of 
the box, I have another sliding piece 3 
P, which fits into the same grooves in 
-the side of the box. Through this 
piece pass two cylindrical rods of soft iron, ¢ 4, 
about two inches in length. They are firmly 
fixed in the wooden slider at their middle parts, 
and parallel to each other. When this piece is in 
its place the iron rods are in the same horizontal 
plane, having one half within and the other half 
outside the box, and their inner ends presented 
to the specimen suspended on the lever. When 
the remaining portion of that side of the box is 
closed by the sliding door, the specimen is nicely 
adjusted to the ends of the iron rods by turning 
the top piece of the tube, until the most trifling 
space is perceptible between them. When all is 
-at rest the poles of the horse-shoe magnet are 
‘made to approach the outer ends of the iron rods, 
bring them into magnetic action, and thus detect 
the magnetism of the specimen if any exist in 
its structure. 
17. By the assistance of this apparatus, to 
which I give the name Torsion Magnetoscope, 
I have examined gold, silver, copper, platinum, 
