Description of a Screw Press . 375 
plate G, for the point of the screw of the press to act 
upon. 
H, the male screw of the press, working in a female 
screw in the centre of the strong cross piece I, which cross 
piece slides up and clown in grooves within the two sides 
of the frame, one of which grooves is shown in the plate, 
and about half the length of the side piece. 
K, the upper part of the iron screw, on which the han- 
dle L, which moves it, is placed upon a square. The 
iron of the screw is only wormed about half its length. 
M, a strong spiral spring, made of iron wire, or iron 
rod, placed in the centre of the cross pieces B and I ; this 
spring presses downwards against the cross piece I, forc- 
ing it as low down as the side grooves will permit. The 
male screw H lies within the circle of this spiral ; and, 
when the screw is turned, passes through the female screw 
below it, and acts upon the iron plate G, under which 
the matter to be pressed is placed, by continuing to turn 
the screw. As it meets with resistance at the point G, 
it gradually forces back the cross piece I, by means of 
the female screw within it, and compresses the spiral 
into a small space, between the two cross pieces, in 
which state it remains, till the article which is pressed 
in the box begins to give out a part of its contents- The 
spiral spring M, compressed as above mentioned, then 
begins to expand, and exerts a continued re-action upon 
the cross piece I, on the male screw II, the iron plate of 
which covers the article under pressure. 
Fig . IS, is the male screw, separated from the other 
parts, to show how far the thread or worm extends 
upon it. 
