342 Capt. Kater’s experiments for determining the variation 
which were sunk in the cross piece, and having been warmed, 
were dipped in pitch to prevent the possibility of their being 
loosened by the motion of the waggon. 
The knife edge was made of wootz, precisely in the same 
manner as described in the experiments on the length of the 
seconds pendulum, its ultimate angle being about 120°. The 
length of the bar from the knife edge to the extremity was 
about five feet, and it terminated in an obtuse angle, serving 
to indicate the arc of vibration. The weight of the whole 
pendulum was 15 lb. 2 oz. 
The perfect immobility of the point of suspension being of 
the utmost consequence, every precaution was taken by the 
arrangement of the form, and by the weight of the frame 
destined to carry the pendulum, to oppose the lateral force 
which might result from its vibrations. 
The frame was of cast iron ; the horizontal part was 19 
inches long, 17 wide, and half an inch thick. The back, three 
inches in width, at right angles to the length was pierced 
with three equi-distant holes in the horizontal direction, to 
receive very large screws about five inches long, with coarse 
threads destined to attach the frame to pickets of wood driven 
into a wall. Two brackets were firmly screwed to the under 
part of the horizontal frame ; these brackets were bevilled so 
as to spread at the bottom to the width of three feet, thereby 
opposing more effectually any disposition to lateral motion. 
In the lower extremities of the brackets, two holes were made 
for screws similar to those above mentioned. The weight of 
the frame was 87 lb. 
A bell metal support, furnished with agate planes on which 
the knife edge of the pendulum was to rest, varied but little 
