EXTEAOEDIi^AEY SHIPS. 
wliy they should not be worked at the same number of atmo- 
spheres as those of the smaller vessel. 
There are other comparisons well worth making as to the dif- 
ferences between the cigar- ship and ordinary shaped vessels. 
In the first place_, make a vertical section of the cigar-ship 
wherever we may_, it presents a 
71 / ' 
AiJ sd' ‘ to te 
Figr. 14. — Superposed Sections of 
Extremities of Ordinary and of 
“ Cigar- ship.”* 
perfect circle {c cc c) ; while in cor- 
responding sections of an ordinary 
vessel the sections are all more 
and more Y-shaped as they approach 
the extremities_, until at last we 
reach the vertical stem, or the stern- 
post. It is quite evident thus that towards either end of 
an ordinary ship there are considerable portions which have 
not sufficient cubical displacement to be self-supporting, and 
which must consequently be buoyed up at the expense of the 
middle portion of the hull. On the other hand, although the 
sections of the cigar- ship present in either direction a series 
of diminishing circles ; yet every part of the ship, being 
Fig. 15. — Diminishing Circular Section of “Cigar ship.” 
actually a frustrum of a cone, has cubical capacity enough to 
be self-buoyant in the water, and is not indebted to any other 
portion for support, and this even to the narrow-pointed end- 
cones beyond the screws. The primary effects of this universal 
buoyancy should be less pitching and ■’scending in. rough 
weather, and a gain of cargo, coal, or engine weight, equiva- 
lent to the dead weight of those unbuoyant parts which an 
ordinary vessel always has, and which the cigar-ship has 
not. 
How if a vessel be properly weighted by her engines and 
cargo in the centre the dead weights at both ends will, although 
acting on a leverage, oscillate freely, like two even-weighted 
boys at the ends of a well-balanced plank in ordinary see- 
saw,^'’ and she will be an easy-going ship. But if one boy 
be heavier than the other, and the plank be not properly 
balanced to meet the difference of weight by corresponding 
* The dotted circles a' to represent the equivalent quantity of 
material to that contained in the ordinary ship’s sections. 
