120 NEW BALANCE. 



His rail also was covered opposite the mouths of his trum- 

 pets with stained paper; but you could feel the vibration on 

 the holes when any one answered, and peoples' hands had a 

 little indented them by accidental pressure. As to a small 

 camera, I do not think it was ever used here, or at all neces- 

 sary for the lady, as a yard of tube with a trumpet mouth 

 would hare answered all the purposes : as, however, you 

 have been at the pains of satisfying the general curiosity in 

 so handsome a manner, excuse me if I request your corres- 

 pondent to complete the instrument by disclosing what he 

 actually knows of the mode of complete vision by director 

 indirect reflection ; being always, 



Sir, 



Your's, 



% G. C. 

 P.S. You have omitted three letters in the diagram of the 



perspective lines. 



VII. 



Description of a new permanent Compemation-Balance for 

 a Time-keeper. By Mr. Wm. Hardy*. 



Description of 

 two compensa- 

 tion balances 

 at present in 

 use. 



Objections. 



E have at present two compensation-balances ; one 

 sort consists of several slips of brass and steel soldered, or 

 fluxed together, and disposed in form of two S S's on the 

 balance, but this is almost now out of use. The other is a 

 steel balance, having a rim of brass fluxed upon its outside, 

 and cut open in two or three places, with sliding weights 

 on the rim, to increase or diminish the effect of the balance. 

 The nature of the balance (the only one now in use) is well 

 known, as well as its defects, which it is unnecessary for 

 me to state at this time, as I shall have a better opportunity 

 of pointing them out at large, should I be ordered to 

 attend the Society. 



Instead of this uncertain way of constructing a balance, 

 which never continues long in the same state, but requires 



* Communicated to the Society of Arts, who voted a reward of 

 thirty guineas. 



to 



