358 On the Construction of delicate Balances. 



2 0.301030 



Sin 30' 7-940842 



Cos 30' 9.999983 



R=005 7.998970 



5.940825 = 0.00008726 inclin. 



9.000169 = C.Log. 6.99961274 inclin. 

 x+ r + 001023+ .005 7-779813 



Sin 30' 7-940842 



7840 3.894316 



8.615140 = 0.0412 grains. 

 Or 0.04 grain would be necessary to produce \ a degree of 

 inclination if the points had a diameter of an hundredth part 

 of an inch; or four times as much as was required by experi- 

 ment, provided the friction was nothing. 



The friction of rolling pivots increases in a very consider- 

 able ratio to the diameter, but as we have no data on which 

 to calculate, it cannot be taken into account in the compu- 

 tation ; however, it would seem that the diameter of the 

 points does not produce so much effect as might be supposed 

 likely. 



A beam fitted up on the bob principle, very roughly 

 finished, as a trial, I have found when loaded with 2,000 

 grains to be sensible to the five-hundredth part of a grain, or 

 a forty-thousandth part ', which would be considered in Eng- 

 land as a good balance. 



In the balance above described, I have used hard steel 

 bearings, as most easily constructed, but if bearings of agate 

 were substituted it would be much better, as steel bearings 

 require to be freely oiled, or otherwise the friction is very 

 great. 



