234 PHILOSOPHICAL TRANSACTIONS. [anNO 1765. 



put upon the hook, and sinks down more or less, according to its weight, till 

 the counterpoise by rising balances it, and then the index or cock of the beam 

 points out, on a graduated arch, the number of skains of that sort which go 

 to the pound. A scale, instead of the hook, might be used for weighing 

 money, if the arch were properly divided for that purpose. 



Mr. Rouse, of Harborough, many years ago, made a machine for sorting 

 woollen thread on the same principle with this ; but as what he did was mostly 

 tentative, he was not aware of some considerable advantages which the theory 

 points out. For the machine will not distinguish with equal nicety the skains 

 of every size. In Mr. Rouse's machine, the divisions were too small, and the 

 largest chanced to fall at 18 to the pound; but it would have been better if the 

 finer sorts had been more accurately distinguished, being of greater consequence 

 to be well sorted, and more difficult to be sorted by the eye only, than the 

 coarser ones. This machine distinguishes best the yarn of 36 to the pound, one 

 of the finest sorts in common use, the largest division lying between 36 and 37 ; 

 the other divisions are as large, and the whole range of the index as much as 

 can be allowed without other inconveniencies. The theory contains the neces- 

 sary rules for finding the angle of the beam, for calculating the divisions on the 

 arch, and for placing their largest interval in any part of them. 



Directions for making the Balance. 



It consists of a mahogany stand, a steel beam and brass ring for the divisions. 

 PGH is the triangular base of the stand, having a screw in each angle to set it 

 level: into this is dove-tailed the upright back kk; the standard board lll is 

 put into a dove-tailed groove in the back, and tenanted into the triangular board 

 at the bottom. The two cocks cc, between which the arbor of the beam plays, 

 and the ring rr, are screwed to the standard board ll. The beam ab, with its 

 cock or index e, is broad in the middle to gain strength, and pierced to make 

 it lighter. It is rivetted on a collet soldered to the arbor, as clock wheels are 

 The pivots run in hard brass, and have plates of hardened steel for their points 

 to bear against. 



At one end of the beam is the counterpoise a, consisting of 2 rtound pieces 

 of brass, screwed together through a hole in the beam. The other end of the 

 beam is made thicker for about half an inch in length, and slit to receive a loop 

 of hardened steel, which hangs on the steel pin b ; on the lower part of the 

 loop hangs the hook, which holds the skain. The block of wood n, is screwed 

 to the standard board; the upper part of which is lined with velvet for the coun- 

 terpoise to rest upon, when the skain is taken off the hook; the brass pin p is 

 for the other arm of the beam to bank against. The angle of the beam acb is 

 l68° 6', the radius ca or cb, 6 inches; the breadth of the beam in the middle 

 J. of an inch, at the ends 4-; the thickness at the end b where it is slit ^; every 



