SS ee er een, 
I i rt a 
66 TECHNOLOGY. 
which turn on the hinges, @, and when closed are held together by the 
hook, 6, jig. 6. Four ring-bolts, r, are attached to the box by which it is 
carried, the brake-bars, m, being put through them. The working parts of 
the engine are now readily understood by inspection of the figure. ¢ is a 
guide-rod which passes through a packing-box at 2’, and insures the recti- 
linear motion of the plunger. Two uprights, x x (jig. 6), support the axis, 
r, of the balance-beam, kK Hx x. The pipe, p q, leads from the air-chamber 
to the hose. Two cross-pieces, n, limit the extent of the stroke. The 
volume of the air-chamber is nearly four times that of one cylinder. Six 
or eight persons can work this engine, and water may be thrown with it to 
a height of 60 feet. | 
A fire-engine constructed on an entirely different principle is that invented 
by Repsold, in Hamburg, in 1843. It works by revolving pistons, and is 
represented in jig. 7 in a side elevation; jig. 8 is a top view of the active 
machinery, jig. 9 a front view, and jig. 10 a section. On a light hand-cart, 
A, is placed a sliding frame, B, which can be fixed in any position by the 
set-screw at B. The engine, £, rests on the platform, cp; the hose, cranks, 
and other apparatus are carried in the box, s. The body of the engine, x, 
consists of a metal box formed by two cylinders partly inserted into each 
other, and closed at the ends with two plates. In this box play the two 
pistons, L and mM, which are mounted on the axles of the wheels, a and 8, 
and are turned by the cranks, rr. The pistons are of an epicycloidal form, 
and so arranged that their surfaces are always in close contact at a line 
between the centres. The larger segment of the epicycloid is in close con- 
tact with the surrounding cylinder, which is effected by a packing on the 
latter of lamina of metal covered with leather, e and 7 Gand u are the 
orifices by which the water enters and is discharged. The action of the 
engine is as follows. Whenever by turning the cranks the pistons, 1 and m, 
are set in motion, revolving in opposite directions, a vacuum will be formed 
before the smaller segment of one piston, and will be filled with water from 
the supply-pipe; the piston in continuing its revolution carries the water 
before it, and throws it out at the opposite orifice. In this way both pistons 
operate alternately, and the pressure of one will have commenced before 
that of the other ceases to act, thus furnishing a continuous stream of water 
without the aid of an air-chamber. An engine of this kind worked by four 
men will do as much work as an ordinary one when worked by six or 
eight men. 
Pl. 14, fig. 16, represents a fire-eengine mounted on carriage-wheels, as it 
is In general use by the firemen in cities. It differs in nothing but the 
larger dimensions from the portable double-acting fire-engine described 
above, and its operation will be readily understood by inspection of the 
figure. The connexion of the several sections of pipe or hose is shown in 
jig. 17. Fig. 21 represents a stop-cock as it frequently occurs in different 
parts of the engine. It will be seen that the cock, a, is so perforated as to 
admit the water in the position in which it is drawn; when turned at right 
angles to that position it will cut it off completely. 
Pi. 14, fig. 22, is a longitudinal section, and jig. 23 a transverse section, 
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