282 Description of a Hydro-pneumatic Blow-pipe. 
which terminates in a very small and delicate jet, and is fitted 
air-tight into the tin or copper tube G. Now, by blowing into 
the tube C, the air is forced out at the bottom of it, and rises in 
bubbles through the water into the upper part of ‘the chamber 
F; this displaces a corresponding quantity of water, which passes 
under the partition D, into the other chamber E, elevating the 
surface of the column of water, and depressing the other, as 
shown in the figure; the water endeavouring to return to its 
original level, causes a constant compressure of the air, and 
forces it through the jet a into the flame of the lamp. By this 
means, it is not necessary to blow constantly with the mouth ; 
for, though the air is forced into the receiver at intervals, yet the 
pressure of the water will expel it in a constant stream, and the 
operator will not be fatigued by the motion of the foot, necessary 
in working bellows, nor need even to keep his mouth at the pipe 
constantly, but merely to blow from time to time, as he finds the 
stream of air to decrease in its power. 
The metal socket which connects the glass tube or blow-pipe 
a@ with the vessel A, is made conical, and the tube, having a piece 
of paper first wrapped round it, is bound round with cotton-wick 
yarn in a conical form, so as to fit the socket tight, and yet per- 
mit the tube to be moved in any required direction, to cause the 
air toact properly upon the flame; and the curved metal tube C 
is also fixed into the upper part of the tube C in the same manner. 
HH are the two sides of a tin frame, which is fixed in front of 
the vessel, and has grooves withinside of them to receive a tin 
plate I, which forms a screen, and can be adjusted in height so 
as to keep the light of the lamp from the operator’s eyes, though 
he can see the work over the top of it: this screen is held fast 
by its foot being placed btween the lid of the vessel and the top 
of the close chamber F. K is one of_ two handles, which sup- 
port the operator’s arms while holding a glass tube or other mat- 
ter in the flame, and there is another like it at the opposite side 
of the vessel: these handles are also wrapped round with woollen 
list or leather, so as to form cushions ; and the vessel is steadily 
fixed upon a chair, bench, &c. by means of a leather strap buckled 
to the loops on each side of it, and passing under the chair, &c. 
The lamp is made of tin, is of an elliptical, or rather of a bean 
or kidney shape, one side being carved inwards ;- across the cen- 
tre of it stands a metal wick-holder, having a loop on one side 
of it, and which is soldered to its bottom, (see 7, fig. 6.) Through 
this loop the wick of cotton is drawn, and being opened both 
ways, as shown in that figure, and still plainer in fig. 8, forms a 
passage in its middle, through which the current of air from the 
jet @ passes as in figs. 4 and 8, and carries the long pointed 
fiame upon the object to be heated. The lamp, figs. 6 and 8, 
is 
