C 82 7 ] 
the pulley H, which is turned different ways, as the 
bar G is moved upwards or downwards. 
There is a pulley p fixed on the other fide of the 
bar G, oppofite the arch-head of the lever F, on 
which the bar rolls ; and which, by the help of a 
flender fpring, keeps it clofe to the arch-head ; to- 
wards the upper end, there is another pulley y, on 
which it alfo moves. 
The expanfion of the bar G, from the place where 
it is fixed to the arch-head d, to the place where it is 
fixed by the firings to the pulley H, is to be added to 
the expanfion of the other three bars, increafed by the 
feveral levers. 
There are two finall pullies h and /, the pulley h 
one inch diameter, and the pulley i a quarter of an 
inch diameter, whofe axis paffes through that of 
the pulley b, like the hands of a clock j and on thefe 
are placed, in like manner, two indexes k and /, 
which move round the dial I, that is 1 2 inches dia- 
meter. Thefe pullies are furrounded by cords, which 
alfo furround, and are faflened to fprings within the 
pulley H. The index /, which may be called the 
minute-hand, is moved 4 times round for once the 
index k is moved round ; the index / ranges at its 
extreme point 48 times as much as the bar G rifes 
or falls ; and the index £12 times. 
As the powers of thefe levers are all reverfed, with 
refpedt to the preflure by the expanfion of the bars; 
there are two counterballance fprings e and/, placed 
under the longer arms of the levers B and D, which 
help to raife the bars eafily ; and there is another fpring 
g> adting on a fmall roller, placed on the top of the 
V ol. LI. f O bar 
