144 ^^' Austin on a new Construction 



into a spherical cavity at (c) to fit the spherical valve of glass 

 (d). This valve is set loosely in the brass piece (^), that it 

 may, when pressed into the cavity, accommodate itself to its 

 proper place. The brass piece [e) has a long tail (/), which 

 passes freely through the milled-headed screw (g), and is sur- 

 mounted at (/) with a small button, with which the valve may 

 be raised, and which prevents it from falling out, when the 

 whole frame is detached from the collar (6), in order to 

 empty or fill the upper vessel (a, fig. i). On the stem (/) 

 of the valve (^), below the milled screw, a coiled spring wire 

 is fixed, the pressure of which on the valve may be regulated 

 by the milled screw. The flanch of the frame [h] has notches 

 cut into it, which fall into corresponding notches in pieces 

 fixed to the ring of the collar. The notches and the whole 

 flanch pass under these pieces with a circular motion, and are 

 thus secured till turned round in such a manner, as that the 

 notches shall again correspond. 



When the collar is not secured by the valve, it drops loosely 

 down on the neck of the upper vessel (a), as represented in 

 the figure at (x). 



Fig. 6, (PI. XIV.) an enlarged view of the hollow glass 

 piston, [a] part of the piston rod. (hb) two small rings to hold 

 the packing, (i:) the packing. (^) the valve, an unpolished plane 

 convex lens, fitted to the end of the piston. (/) the plan of 

 the end of the piston, the latter is placed on the plane side of 

 the lens, [eeee] notches in the upper small ring of the piston, 

 over which are passed crossed threads, in order to confine 

 the valve (/), and to prevent it in action from being carried 

 of! the end of the piston. The notches are necessary to 

 guard the threads fiom the attrition of the barrel. 



