8 . 
POPULAR SCIENCE REVIEW. 
of water describes a circle in a vertical plane. At the surface, 
the diameter of these circles is the whole height of the wave, 
from valley to crest. The circles rapidly diminish in size as 
their depth below the surface increases. Taking into account 
this diminution, as well as the effect of the ship’s breadth, it is 
certain that the ship will not follow this circular motion at all 
to the same extent as a cork floating on the surface. In 
moderately heavy weather, it is probable that, in such a ship as 
that which Mr. Eeed has designed for Mr. Bessemer, any fixed 
point would describe a vertical circle of five or six feet in 
diameter in rough weather, quite independently of any rotatory 
or rocking motion. The model exhibited at Denmark Hill 
simply oscillated on a fixed centre, and therefore the experi- 
ment did not go to this point, as it might have done if it had 
been mounted on a crank or eccentric. It does not, therefore, 
tell us how far this remains as a real cause of uneasiness, 
especially when combined with a small amount of pitching, 
after the rocking or rolling is got rid of. While, therefore, I 
am unable to look forward to the absolute prevention of sea- 
sickness with the full confidence expressed by the promoters, I 
have not the slightest doubt that the remedy will be all but 
absolute, and that the residual motion will only affect extremely 
sensitive persons in exceptionally rough weather. Even for 
these, it will be nothing like what they undergo at present. 
The invention of springs has not entirely cured the shaking of 
a carriage ; but I believe that the comparison of the motion 
in the Bessemer saloon with that in the present boats, in a 
rough sea, will be much the same in degree as that between a 
well hung carriage and a waggon or tumbril on a rough road. 
The mode of propulsion, by two pairs of paddles, one working 
in the wash of the other, is not very favourable to economy of 
fuel. There is practically, however, no help for it ; and as the 
voyage is a short one, this question is of secondary consequence. 
The great length and breadth of these vessels will make it 
somewhat more difficult for them to enter the French harbours- 
than for smaller boats ; and therefore there will, I think, be a 
few rough days in the year when smaller vessels will have ta 
perform the mail service. With this reservation, I have na 
doubt as to their being perfectly safe — in fact, all the safer on 
account of their large size. An accident to the saloon, or to 
the machinery which moves it, would simply have the effect of 
setting it fast, and the worst that could happen from this cause 
would be, that the passengers would not get the relief desired, 
but would simply be as in the saloon of an ordinary ship, only 
with much better ventilation. 
Another plan, remarkable for its divergence from the ordi- 
nary form of ships, is the double steam-ship proposed by Captain 
