transverse frames dividing the hull into compartments, with tubes
completely encircling the section between each main transverse
frame. The system of wiring the hull is precisely the same in
both the ships, and nets are employed in the same way.

The triangular section of keel is adhered to, but its functions
in No. 23 are somewhat different. In No. 9 it was intended to be
sufficiently strong to support all the main vertical bending
moments and shearing forces, but in No. 23 it was primarily
intended to support the distributed weights of water ballast,
petrol tanks, etc., between the main transverse frames. Unlike
No. 9, the keel is attached to the main transverse frames only.
The cabin and wireless cabin are disposed in the keel in the same
manner, and it also furnishes a walking way for the total length
of the ship.

The stabilizing fins, both vertical and horizontal, are similar
to those attached to No. 9, but the system of rudders and
elevators is totally different. In place of the box rudders and
elevators in No. 9, single balanced rudders and elevators are
attached to the fins; they have their bearing on the outboard
side on the external girders of the fins, which are extended for
the purpose. The elevators and rudders are composed of a
duralumin framework, stiffened by a kingpost on either side with
bracing wires.

The bags, eighteen in number, are made of rubber-proofed fabric
lined with gold-beater's skin. It is interesting to note that
the number of skins used for the bags of a ship of this class is
approximately 350,000. The system of valves is entirely