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leaks, but also when we stop the pump and put the plunger in 
the lowest position in order to reduce the possibility of leakage as 
much as possible. 
The fly-wheel is connected on one side of the crank with a pin, 
on the other side a toothed wheel is fastened which receives the 
motion by a chain from a second toothed wheel on the shaft proper. 
This shaft runs in a supporting piece fixed tightly by means of 
strong screws to the frame and strengthened by a separate oblique 
stay. 
The wheel is drawn in the figures of Pl. II on the shaft over 
which the leather belt runs to an additional shaft worked by a 
steam engine. In the Leiden laboratory this latter shaft is on the 
wall opposite the pump. Instead of the steam engine we can also 
employ an electromotor of 1 H. P. (75 K.G.M. per sec.) by means 
of a large and lightly built wheel of 1 meter diameter and the same 
additional shaft. Finally there is an arrangement for placing a 
handle on the shaft of the pump, so that one or two men can turn 
this at the proper speed (§ 2 3 3). 
Ò. Compression tube and the communication of the mercury of 
the compression tube and the pump cylinder. The thick-walled for- 
cing cylinder C' rests with its base C's) on the frame V, screwed 
on to it tightly with four bolts C’; the exact position being determined 
by four pins C's. 
A direct connection with the pumpeylinder was made impossible 
owing to the frame and the crank. 
Therefore, a little above the bottom of the cylinder a bored tap 
with screw-thread C's is forged on, on which the thick-walled bent 
connection-tube dod, (see Pl. IIf, VI fig. 1 and Pl. II) is fastened 
by the nut d,. The T-picce dz forms a junction between the elbow 
d, and the double bent tube ds, which is fastened with the nut d, 
on the pump proper ¢ (Pl. V) this being itself provided with a 
screw-thread. 
The nut d, rests on the tube by means of a collar dz forged on 
to dj, and a closure is obtained by the washer d;. The fastening 
of the nut d, was a little more complicated. On the tube ds, is 
screwed a ring ds, above which is placed an india-rubber ring de 
and a plate dss, which can be pushed over the screw-thread of d3,, 
this being slightly rounded off towards the upper end by the addition 
of a rounded ring dz, The india-rubber ring is thus completely en- 
closed and in tightening the nut d, this india-rubber gives a 
perfect closure. 
