174 
THE YOUNG SCIENTIST. 
and e f similarly occupies the place of e r 
in -the same flgure. The depth from n or 
1 to the line p p" is that of the extreme 
height of the bow from the load water- 
line A B (Fig. 1). 
For Fig, 3 the semi-breadth of beam is 
set off on each side of the line p' q, as at 
T 63, Q i, and v ©" ; q cj the distance, ®' i 
being made equal to ® i (Fig. 1), or the 
after part of the hull, and the dis- 
tance ®" g bein^ equivalent to that 
of © G (Fig. 1), or the fore part of the 
boat. The two lines n' and holding 
corresponding positions to n l (Fig. 1), 
are also drawn. 
The designer is now able to fill in the 
cross -section lines and the water-lines of 
the craft. We may mention that the 
small figures as 1, 1', and 1" indicate 
similar i)oints in the three figures. 
The shape of the boat itself (shown in 
Fig. 1 by the diagonal shading) is in the 
main dependent on the taste of the de- 
signer; but much care and discretion 
should be exercised on its careful jn-opor- 
tionment and outline. That part above 
the load water-line is termed the free- 
board, and may differ considerably, ac- 
cording to the destination of the boat. It 
may be well to state that there is no 
necessity for shading the outline of the 
boat as in Fig. 1. It is only done in this 
instance to render our instructions more 
clear. 
The lines 1' 2' 3' and 4' 5' 6' are now to 
Ibe drawn on Fig. 3. These lines repre- 
sent the load water-line a b (Fig. 1) for 
both ends of the boat. 
The lines 1 1' 1" x and 4 4' 4" x in Fig. 
2 are next put in, representing the mid- 
ship section, and therefore necessarily 
liaving the same degi-ee of curvature. 
This curvature depends upon the taste of 
the builder, except in so hxx as it is gov- 
erned at the load water-line by the dis- 
tances of the lines 1' and 4' on Fig. 3 f "om 
the line v q. I 
In the cross-sections (Fig. 2) the lines 
!2 2' 2' X and 5 5' 5" x are next put in. 
These are shown on Fig. 3, at?i' andr, 
and must be set off from the perpen- 
dicular R s (Fig. 2) on the line p p and 
equivalent distances at 2' and 5' to the 
snme distance as 2 and 5' from the hori- 
zontal line V Q at Fig. 3, the remainder of 
the curve being a matter for the de- 
signer's taste and discretion. The line 
3 3' 3" for the stern is next drawn, and the 
cross-sections completed. It will be seen 
lhat the section to the left of the line e s 
is the after-part of the boat, and the por- 
tion to the right of that line is the forward 
half of the boat from amidships. 
Fig. 3 may now be completed by the in- 
sertion of the remaining water-lines. We 
already have 1' 2' 3' and 4' 5' 6' for the 
load water-line. It is now necessary to 
put in 1" 2" 3" and 4' 5" 6", correspond- 
ing to the line e f on the sheer plan (Fig. 
1), and the lines 12 3 and 4 5 6, corre- 
sponding to the line of the gunwale, as 
denoted by the same figures in the sheer 
plan. 
It is thus clear that we have at Fig. 2 a 
series of vertical sections of our boat, and 
at Fig. 3 three horizontal section s of the 
same. If we imagine the boat cut into 
three flat slices by sawing it through at 
the two lines a b and e f (Fig. 1), we have 
the outlines of the planes given at Fig. 3. 
In order to render our meaning more 
plain, we have shown the plane of e f 
(Fig. 1) on Fig. 3 as filled in by shading 
diagonal lines sloping from riglit to left. 
In a similar manner the superfices at the 
load water-line a b (Fig. 1) is shown by 
lines slanting from right to left, while 
the length and breadth of the boat at the 
gunwale are denoted by vertical shading. 
It must be understood, however, that no 
such shading is needed in the regular 
working drawings. 
Vessels of all kinds are designed in a 
very similar manner. Sometimes the 
section is termed the "body plan," and 
the plan of the water-lines the "half- 
breadth plan." Thus Fig. 4 shows the 
sheer plan of one of our large steamers, 
Figs. 5 and 6 the half-breadth plan of the 
same vessel, and Fig. 7 the sections or 
body plan. An inspection of these con- 
struction drawings may serve to render 
the foregoing remarks more easily under- 
stood. It will be seen that the straight 
load and other lines shown at 1, 2, 3 in the 
sheer plan become curves in Figs. 5 and 
6, while, contrariwise, the lines 1', 2', 3', 
which represent vertical planes, from the 
