of a new Pendulum . 5 
but if their expansion and contraction is to be compensated 
for, the fixed point will be at I, as has already been shewn. 
If the expansion and contraction of the rod IB by heat and 
cold, in proportion to the expansion and contraction of CD, 
were known, and the expansion and contraction in perpendicu- 
lar height of IE, then the length IB should be to the length 
DC, as the contraction of the materials of CD is to the con- 
traction of the materials of which IB is constructed, added to 
the contraction in perpendicular height of the materials of 
which IE is constructed. These lengths, in this case, might 
be taken at once ; but it is much more convenient to have the 
power of fixing them by experiment, after taking them from 
measure as nearly as may be. 
Therefore, to have a means of raising the point I higher or 
lower in proportion to ED, whose ends are always to be at the 
same distance from one another, fig. 2. represents the means of 
altering the point I in proportion in height to E. The frame 
AAAA is fixed to the substance which connects the points 
I and E by any means. In the clock which I have constructed, 
the material which connects I and E is wood, as will be de- 
scribed afterwards. The frame is brass ; it is fixed to the wood 
by the screws B B, and two other opposite ones which are hid 
in the drawing. They are so fixed that the point I shall be 
nearly in the middle between the upper screw B, and the lower 
screw B, and so that the part of the frame DDDD shall pro- 
ject backwards, and carry the part of the frame EEEE behind 
the frame which forms the connection between I and E, so as 
to be parallel to it ; of consequence perpendicular to the hori- 
zon. In this frame there is seen, at the upper part, in the draw- 
ing, a dove-tail groove, in which, on both sides, another frame 
mdccxciv. C 
