GARDEN MECHANICS. 
81 
much greater than the transverse section of the body of the 
ram, whilst the short cylinder is screwed by its flanch into the 
opening of the upper surface of the head. The flanch of the seat 
is so formed as to have an inverted cap round the upper part of 
the short cylinder, forming a circular channel or annular space 
without the head of the ram, which will contain air, and from 
which the latter cannot escape when compressed by the water. 
This air it is that is called the matrass, and the shifting valve is 
at the end of a small pipe which leads from the matrass to the 
open air; the shifting valve opens inwards in order to admit the 
air to enter into the matrass, and to prevent its return there is 
another small valve which opens outwards, whose object is, in 
addition, to admit a certain quantity of air, and then to shut and 
prevent any further entrance. 
“ On the outside of the seat of the stop valve, or over the aper¬ 
ture in the head of the ram where the water issues, another stop 
valve is applied, similar to the internal valve before referred to, 
which shuts down on the outside of the seat. The upper part of 
the pipe or head is made flat at the part near the end, where it 
enlarges to a sphere; and this flat surface has several narrow 
openings across it, which are covered by as many flap valves 
made of leather, in order to allow water to pass out and prevent 
its return. On each side of the head of the ram, at the part op¬ 
posite these flap valves, is a hollow enlargement in the form of a 
segment of a horizontal circle, and the two enlargements taken 
together form a circular basin, through the centre of which the 
pipe of the ram passes ; this circular basin is covered by a cylin¬ 
drical air vessel, screwed down by means of a flanch at the edge, 
so that it forms the bottom of this space ; and in consequence of 
this arrangement all the water which issues from the body of the 
ram through the flap valves will flow off on each side, and be re¬ 
ceived in the basin. As, however, the circular basin is divided 
into parts by the pipe of the ram which passes through it, there 
is a passage communicating from one of the enlargements to the 
other, for which purpose it curves down and descends beneath 
the pipe of the ram. The ascending pipe that carries away the 
water which the machine raises proceeds either from this curved 
passage or some other part of the basin; so that it may receive 
the water which has passed through from the body of the ram 
