ontrolled. The side valve is set to
blow off at a pressure of from 3 to 5 millimetres. The outer cover was
fitted in the same manner as in No. 9. Two cars or gondolas, one
forward, the other aft, each carry one engine provided with swivelling
propellers and gears. They are enclosed with sides and a fireproof
roof, and are divided into two compartments, one the navigating
compartment, the other the engine room. The cars are in all respects
very similar to those of No. 9, and are suspended from the hull in a
similar manner. The remaining two engines are carried in a small
streamline car situated amidships, which has just sufficient room in it
for the mechanics to attend to them. Originally this car was open at
the top, but it was found that the engineers suffered from exposure,
and it was afterwards roofed in.

The engine arrangements in this ship were totally different to those of
No. 9, four 250 horse-power Rolls Royce engines being installed in the
following order. Single engines are fitted in both the forward and
after cars, each driving two swivelling four-bladed propellers. In the
centre car two similar engines are placed transversely, which drive
single fixed propellers mounted on steel tube outriggers through
suitable gearing.

The engines are the standard 12 cylinder V-type Rolls Royce which will
develop over 300 brake horse-power at full throttle opening.

The engine is water cooled, and in the case of those in the forward and
after cars the original system consisted of an internal radiator
supplied by an auxiliary water tank carried in the keel. It was found
on the flight trials that the cooling was insufficient, and external
radiators were fitted, the internal radiator and fan being removed. In
the case of the centre car no alteration was necessary, as external
radiators were fitted in the first instance.

The engines are supported by two steel tubes held by four brackets
bolted to the crank case, these being carried by twelve duralumin tubes
bolted to the bearers and transverse frames of the car respectively.
The drive from the engine is transmitted through a universal joint to a
short longitudinal shaft, running on ball bearings. This shaft gears
into two transverse shafts, which drive the propellers through the
medium of a gear box to the propeller shafts, making five shafts in all.

The engines in the centre car being placed transversely the
transmission is more direct, the engines driving