132 On Specific Gravity. 
A more particular explanation of the principle of the sec- 
tor, may be found in any Encyclopedia, or Dictionary of 
Mathematics. 
- Before taking Teave of the reader, it may be proper to ex- 
plain n the use of the square dish, which may be seen to the 
‘left, under the beam, (figure 5-) The are of wire, is for 
the purpose of suspending the dish to the hook, in place of 
the outer bucket- When so suspended, filled with water, and 
in 
means of the ch ometer, it is easy to ascertam the different 
— evaporated, in similar times, and at different pe- 
, in different places; so that, guarding against the 
effects = saat currents, hydrometrical observations may be 
made with great accuracy. 
