38 Capt. Kater’s experiments for determining the 
A cylindrical weight of brass, three inches and a half dia- 
meter, one inch and a quarter thick, and weighing about two 
pounds seven ounces, has a rectangular opening in the direc- 
tion of its diameter, to admit the knee pieces of one end of 
the pendulum. This weight being passed on the pendulum, 
is so thoroughly secured there by means of a conical pin fit- 
ting an opening made through the weight and knee pieces, 
as to render any change of position impossible. A second 
weight of about seven ounces and a half, is made to slide on 
the bar near the knife edge at the opposite end ; and this 
weight may be fixed at any distance on the bar by two 
screws with which it is furnished. 
A third weight, or rather slider of only four ounces, is 
moveable along the bar, and is capable of nice adjustment by 
means of a screw fixed to a clamp, which clamp is included 
in the weight. This slider is intended to move near the 
centre of the bar. It has an opening, through which may be 
seen divisions, each equal to one twentieth of an inch, en- 
graved on the bar ; and a line is drawn on the edge of the 
opening to serve as an index to determine the distance of the 
slider from the middle of the bar. 
We now come to the most important part, the knife edges. 
These are made of that kind of steel which is prepared in 
India, and known by the name of wootz. Their form is 
triangular, and their length one inch and three quarters. Mr. 
Stodard was so obliging as to forge them for me : they 
were made as hard as possible, and tempered by immersing 
them merely in boiling water. 
The knife edges were ground on a plane tool, which ne- 
cessarily ensured a perfectly straight edge. This was ascer» 
