THE 
POPULAE SCIENCE EEYIEW. 
EXTRAOKDINAEY SHIPS. 
BY S. J. MACKIE. 
»<>• 
T here is a considerable difference between a Dntcb 
galliot and a British three-decker/^ but scarcely 
greater to the eye than will be the difference between an 
ordinary steam-ship of the present day and those of futurity 
if Winan^s yacht should prove a success. But the cigar- 
ship ” now building in Mr. Hepworth^s yard^ on the Thames_, 
is not the only strange ship projected or afloat; and a few 
words on a few extraordinary ships will not at this season 
be out of place. Up to the running of the Comet on the 
Clyde in 1812 ^ the ships of every age had been essentially 
sfli/wi^-vessels. Oars worked by human hands were the only 
aids employed. But the introduction of steam marked 
altogether a new era in ship -building. With the introduction 
of a self-carrying power of propulsion through the luater, points 
of construction previously of minor moment in sailing-ships^ 
became matters of fundamental importance in steamers. In 
shorty the primary and chief obstacle to progression was the 
resistance of the water to the moving object. This was formerly 
estimated as increasing as the square of the velocity^ while 
the cubes of the squares were taken as the requisite driving 
steam-power. The midship section of the old bluff-bowed 
vessels was taken as practically a square area to be driven 
by main steam-force through the water. It is evident the 
limit of steam-power would soon be thus attained. And so 
it was. Another mile an hour was got by putting on more 
steam-power ; and then more steam_, and another mile or two ; 
and then — the engines broke down. But the direct resistance 
which a plane surface has to overcome is not experienced by 
triangular or wedge-shaped bodies ; hence the idea of adding 
VOL. IV. NO. XIII. B 
