g itself and the
outside planking diagonally. Sometimes the holds were strengthened with
vertical and sometimes with diagonal riders, but none of these plans
gave lasting satisfaction.

The means adopted by Sir Robert Seppings were as follows:--

Firstly, the spaces between the frames were filled in solid with timber
(Fig. 62). In this way the bottom of the ship was transformed into a
solid mass of timber admirably adapted to resist working. At the same
time the customary interior planking below the orlop beams was omitted.

[Illustration: FIG. 62.--Sir Robert Seppings' system of construction.]

Secondly, the beams were connected with the sides of the ship by means
of thick longitudinal timbers below the knees running fore and aft,
called shelf-pieces, _a_, _a_ (Fig. 63), and similar pieces above the
beams, _b_, _b_ (Fig. 63), called waterways. These not only added to the
longitudinal strength of the ship, but formed also very convenient
features in the connection between the deck-beams and the ship's sides.

[Illustration: FIG. 63.--Sir Robert Seppings' system of construction.]

Thirdly, a trussed frame was laid on the inside of the transverse frames
in the hold of the ship. This frame consisted of diagonal riders making
an angle of about 45 deg. with the vertical, together with trusses crossing
them, and longitudinal pieces, as shown in Fig. 62. This trussed frame
was firmly bolted through the transverse frames and the planking of the
ship.

Fourthly, it was proposed to lay the decks diagonally; but this system
does not appear to have ever come into general use.

It should here be mentioned that the use of shelf-pieces and thick
waterways in connection with the ends of the beams was first adopted by
the French in very small vessels; also the system of fillings between
the frames was an extension of a method which had been in use for some
time, for it was customary to fill in the spaces as far as the heads of
the floors, in order to strengthen the ship's bottom against the shocks
and strains due to grounding.

[Illustration: FIG. 64.--Sir Robert Seppings' system of construction.]

Sir Robert Seppings further introduced many minor improvements into the
details of the construction and the forms of ships. Amongst these may be
mentioned the method of combining the frame-timbers. The old method of
shaping the heads and heels of these timbers and of combining them with
triangular chocks is shown on the left-hand si