184 Count Rumford’s Inquiry concerning 
and consequently the greatest possible accuracy, when used at a 
time when the temperature of the air is the same as when the 
balance was made, yet, as it may happen, that in order to bring 
the arms of the balance to be of the same length, one of them 
may be much more hammered than the other, I suspected it 
might be possible that the texture of the metal forming the 
two arms might be rendered so far different, by this operation, 
as to occasion a difference in their expansions with heat ; and 
that this difference might occasion a sensible error in the 
balance, when, being charged with a great weight, it should be 
exposed to a considerable change of temperature. 
To determine whether the apparent augmentation of weight, 
in the experiments above related, arose in any degree from this 
cause, I had only to repeat the experiment, causing the two 
bottles A and B to change places upon the arms of the balance; 
but, as I had already found a sensible difference in the results of 
different repetitions of the same experiment, made as nearly as 
possible under the same circumstances, and as it was above all 
things of importance to ascertain the accuracy of my balance, 
I preferred making a particular experiment for that purpose. 
My first idea was, to suspend to the arms of the balance, by 
very fine wires, two equal globes of glass, filled with mercury, 
and, suffering them to remain in my room till they should have 
acquired the known temperature of the air in it, to have re- 
moved them afterward into the cold, and to have seen if they 
still remained in equilibrio, under such difference of tempera- 
ture; but, considering the obstinacy with which moisture ad- 
heres to the surface of glass, and being afraid that, somehow 
or other, notwithstanding all my precautions, one of the globes 
might acquire or retain more of it than the other, and that by 
