on Drummond’s Light made at Constantinople. 241 
an inch deep in the diaphragm of the inner cylinder to receive 
its end; the inner cylinder, therefore, being placed within the 
other, its edge rested on the bottom of the latter. To fill the 
gasometer, the interior cylinder was taken out, and water 
poured into the other to the level 7; the former was then re- 
placed, the stopcock ¢ opened, and the air expelled till the 
diaphragm reached the surface of the water; the gas was now 
introduced at the stopcock, and the gasometer thereby raised : 
twenty-seven inches of water were now poured into the part B, 
which, together with the weight of the tin, made up the whole 
pressure of thirty inches. This forced part of the water in D 
up the sides of the vessel, and other water was added till 
the external water rose to the level L, which is twenty-nine 
inches above the top of the pipe; and consequently restored 
the water in the lower part of the gasometer to its original 
level 7. It is now evident that as many inches of gas as are 
let off are supplied by the upper part descending ; and the sur- 
face of the upper and lower diameter being the same, the level 
of the water at 7 and L always remained the same, and con- 
sequently the pressure. There is, moreover, very little friction, 
and the action is soft and equal. The oxygen gasometer was 
constructed in the same manner; but being only required to 
hold half the quantity, its area of bottom was made only half 
the former, the height being the same. The other parts are 
easily comprehended: c’ is another cock; m, the mixing-box ; 
S, S, its supports; p, the emission pipe; and ', the lime-ball. 
Fig. 3 is a plan of the whole, showing both gasometers. The 
mixing-box is made by soldering the pipe m into the outer 
pipe , which has a diaphragm pierced with holes; the part of 
the pipe m projecting through it has also holes round its side. 
The lamp is lighted thus: the hydrogen being let on by 
Fig. 3. Hydrogen. 
its stopcock being opened, passes into m, and through the 
Third Series, Vol. 8. No. 46. March 1836. 2C 
