[ 2o6 ] 
more or Icfs, according to its weight, till the 
counterpoife by rifing balances it, and then the 
index or cock of the beam points out, on a gra- 
duated arch, the number of fkains of that fort, 
which go to the pound. A fcale, inifead of the hook, 
might be ufed for weighing money, if the arch were 
properly divided for that purpofe. 
Mr. Roufe of Harborough, many years ago, made 
a machine for forting woollen thread upon the fame 
principle with this j but as what he did was mohly 
tentative, he was not aware of fome confiderable 
advantages which the theory points out. For the 
machine will not diftinguifli with equal nicety the 
fkains of every fize. In Mr. Roufe’s machine, the 
divifions were too fmall, and the largefl chanced to 
fall at 1 8 to the pound j but it would have been 
better if the finer forts had been more accurately di- 
flinguifhed, as being of greater confequence to be 
well forted, and more difficult to be forted by the 
eye only, than the coarfer ones. This machine di- 
llinguiffies bed: the yarn of 36 to the pound, one 
of the fined forts, as I am informed, in common 
ufe, the larged divifion lying between 36 and 37 ; 
the other divifions are as large, and the whole range 
of the index as much as can be allowed without 
other inconveniencies. The theory contains the ne- 
cedary rules for finding the angle of the beam, for 
calculating the divifions on the arch, and for placing 
their larged interval in any part of them. 
DlreSiicm 
