( 450 j 
merous fine holes fg. The valve-pin f; which is carefully ground 
on the valve-support, is guided in it by means of the cylindrical 
rod #5, while the conical part fs, closes the openings in the 
valve-support. The valve-pin is constantly pressed against the valve- 
support by the small spring f,7 and the small pin f5;. The valve- 
support can be screwed out by means of the doubly interrupted 
ring fz, which is turned out of it. An india-rubber plate f;, is fas- 
tened on the valve-pin by means of the screw f52; a four-armed 
steel spring fs4 presses the edges of the india-rubber plate lightly 
against the valve support. It requires then some excess of 
pressure on the forcing-side to press the steel valve tightly on 
to the valve support. Should this happen at high pressure the 
india-rubber sheet rests simply on a flat surface formed by the upper 
part of the valve-cone and the upper-side of the valve-support. ‘The 
screw stopper or valve-box-lid f, with the packing fs allow us to 
test whether the valve works well and to remove the valve-support 
with its valve from the valve-box. 
t. Safety feeding-valve. The valve-box and the exhaust-box fo, adja- 
cent to it are formed of one piece of forged steel ; the boring fy forms 
the communication between the exhausted space f, and f;,,, the 
space left between the ring fz, and the valve-box-wall, and the 
suction-chamber fy, in which the gas enters from the sucking-tube 
Jiro) if the valve gz is not closed (comp. § 2 € 2). 
A small cylinder gg2 provided with two notches is connecied to 
this valve by a rol gs, and peg 9310, on which rod is cut a screw- 
thread with which it can be serewed up and down through the 
packing gs3 by a thread in the serewhead gs. This screwhead is 
provided on its innerside with a thread. If the small peg gsi. is 
held, then the small rod must, by the rotating motion of ggg, slide 
up and down without turning as is necessary in order to loosen it 
(comp. § 2 € 1). The serewhead is turned by means of the disc 
Yan Of Jaa: 
The lowerside of the tube g,, against which the safety-valve 
presses is rounded towards the inner side (comp. gj9;) to ensure a 
better closure of the valve. The coating ga, of india-rubber mixed 
with much zine white is tightly forced into the conical cup 
9a) +) and requires only little pressure to assure the closure. As a 
rule the valve lies on three ridges gy;, made on a supporting ring 
) Additional valves are turned on the lathe to the correct size and kept in stock, 
