On the Transmission of Power to a Distance. 3 
horizontally in the warehouses by means of broad belts. It is 
found that 50 tons of grain can be carried in this way on belts 
18 inches wide a distance of 100 feet in an hour, with an expen- 
‘diture of 1:02 horse-power. (The same quantity moved by screw 
required 18°18 horse-power.) Hydraulic machinery has also been 
most successfully applied to work foundry cranes, coal hoists for 
loading ships, opening dock-gates, opening drawbridges, working 
rivetting machines, forging machines, &c. 
Air-pressure machinery is used for working hauling machines 
in mines where steam could not be used, and coal-cutting machines 
and tunnelling machines. 
The pneumatic transmission for telegraph messages was an ap- 
plication of pneumatic power. The whole arrangements would 
require too long to perfectly explain. 
Lately air-pressure machinery had been adopted for applying 
brakes to railway trains. There are several methods now being 
tried for applying brakes. In Clarke & Webb’s Brake, which is 
used by the London and North-Western, and the Heberline 
Brake, the power is obtained from the rotation of one of the 
wheels by means of friction wheels, and is transmitted to several 
carriages by means of a chain, which is wound up on a drum. 
The Westinghouse Brake is a pressure brake, that is, the air is 
used under pressure. Under each carriage is placed a reservoir 
for compressed air, and a cylinder in which a piston works. 
When the air is admitted from the reservoir to the cylinder the 
piston moves, and, being attached to the brake gear, puts on the 
brake. The reservoir is kept filled with compressed air by an air 
pump on the engine. There is an arrangement which is very 
complicated to explain, even with a diagram, by which this brake 
is made automatic, that is, whenever the pressure in the tubes 
which connect the carriages and engine is lowered, either inten- 
tionally by the guard or driver, or by accident, as by the separat- 
ing of the train, the brake goes on itself. This brake is very 
powerful and rapid in its action, but certainly has some points 
about it which make it complicated. 
The Smiths’ Vacuum Brake has the power obtained by pro- 
ducing a vacuum by means of a steam jet exhauster on the 
engine. There are two tubes run along the train, which are in 
connection with a cylindrical bag or sack which is placed under 
Scren. Proc, R.D.S., Von, m., Pt. 1. B2 
