9. Second Fire-Escape
OF A SECOND FIRE-ESCAPE,
By breaking the Fall.
This Machine is also shewn in Plate 46, at fig. 1. It consists of a large truck,
A, to be drawn rapidly to any
house on fire, by one or more horses. The carriage or frame part
B B, is an
open square frame
subtended by a first sheet of sack cloth, similar to the sacking of a bed: and on this are laid five, or more,
air mattrasses made of sack cloth, and varnished on the inside so as to be nearly air-tight; I say
nearly so, for it is
not intended they should form a spring capable of
returning any object thrown on them. On the contrary, each of the mattrasses has, at one or both ends, a valve 1, 2, &c. opening
outwards, but kept closed by proper springs, so as to determine the pressure at which the air shall escape; that pressure being carefully graduated, so that the upper mattrass shall give way with ease, the second with greater effort, and the successive ones with progressive difficulty, until the under one remains totally closed, and stops the falling body altogether. By these means, if enough mattrasses are used, and they are
duly regulated, a person may jump from a house of three or four stories without incurring any danger. As to the length and breadth of this fire-escape, it should be ample enough to give the sufferers confidence to take the leap, and as small as an easy passage in the principal streets would require.
One thing must be described in
words--as the mechanism to which it relates is fixed under the truck; and could not be seen in this perspective figure. These mattrasses are filled with air by an
horizontal air pump, worked by a
crank, which the axle itself of the hind wheels of the truck forms: whence, by pinning this axle to either of the hind wheels, the very motion of the carriage, as drawn by the horses, would distend the mattrasses--which would thus be ready for use the moment they arrived on the spot; and moreover, when there, this air could be replenished, after using, by turning this axle, through the wheels,
by hand cranks slipped on it's ends at the place of the linch-pins. Or, in fine, this operation might be performed by an air pump prepared for it alone, and placed in any convenient part of the Machine.