Cooper’s Rotative Piston. 317 
sion of the other power, while changing the brakes. The 
engines in New-York are all of this construction, and are so 
made as to allow the brakes to run the whole length of the 
engine on each side. The leverage is generally twenty four 
inches, and the number of men required to work them about 
twenty. The engines, manufactured in Philadelphia and 
Boston, likewise work with pistons, but the levers are differ- 
ently constructed, there being generally one long lever run- 
ning the whole length, having its fulcrum in the centre, while 
the brakes are placed at each end. Some of the Philadel- 
phia engines are of great power, allowing from thirty to for- 
ty men to work at once, and have from two to four feet lev- 
ers. Another mode of making engines has been tried with 
success, which is to place a small cylinder within a large hol- 
low one, and attach a wing or. arm to the small cylinder, and 
make it sufficiently long to fill the space between the two: 
a stop is then placed on the opposite side of the small cylin- 
der, fitted at the end next to the inner cylinder, so as to allow 
it to play on that end, while the other is attached firmly to 
the outer cylinder. Heads are put upon the outer cylinder, 
secured to it by flanches, and the gudgeons of the inner cyl- 
inder are secured by stuffing boxes; levers are put int 
ends of the gudgeons of the inner cylinder, to which the 
brakes are attached. Two sets of valves are made use of, 
one between the outer cylinder and pipe, the other between 
the cylinder and air chamber. An engine of this kind is now 
used by the Sun Fire Insurance Com London, and 
one of nearly the same construction, by the name of the Cat- 
aract, has been in Boston for several years, and is still in use. 
In many of our‘ cities the organization of the fire depart- 
ments is excellent; and particularly in New-York, Philadel- 
phia and Boston, the vigilance and success of the firemen 
have inspired a confidence which does honor to them, and te 
the cities to which they belong. The engines, in these pla- 
ces, are always found in excellent order, and at first sight, it 
would seem that human skill and ingenuity-had been exhaust- 
ed in rendering them perfect; but, upon myestigation, many 
defects will appear, which should be remedied as far as prac- 
ticable. The first of these defects is the expense necessary, 
not only to construct, but to work them and keep them in 
repair, The best New-York engines cost from seven to cight 
hundred dollars, including suctron hose, and throw through 
their pipes (3-4 inch) from eighty to one hundred gallons per 
