4 
POPULAR SCIENCE REVIEW. 
the French coast impose considerable restrictions upon this, 
especially as regards draught of water. At or near low water, 
six or seven feet is all that can be depended upon, and this 
only in still weather. With large boats, accordingly, any 
idea of a service at fixed hours, irrespective of tide, must be 
abandoned, and there will also be certain rough days in which 
small mail steamers can enter the harbours when the larger 
boats cannot do so with safety. There can be no question, 
however, that no real improvement can be effected without 
larger boats. Three or four years ago the Society of Arts 
offered a prize for a model of good arrangements for deck 
passengers aboard vessels of the same size as those now in use. 
Of more than twenty models submitted for adjudication, only 
three or four complied with the conditions laid down as to size, 
and these three or four showed no real improvement. Under 
these circumstances no prize could, of course, be awarded ; 
but it was quite evident to the writer (who was one of the 
committee), that the limitation as to dimensions rendered a 
good deck arrangement impracticable. The only really im- 
proved designs postulated increased dimensions. 
Of the schemes which have been laid before the public, while 
there are several which aim at reducing the amount of motion, 
and of consequent sea-sickness, by due proportion and dimen- 
sion, there is only one which takes special and direct means of 
securing that the passengers shall not partake of the motion of 
the ship. That scheme is Mr. Henry Bessemer’s. 
Most of our readers must have noticed the way in which a 
ship’s compass, and the cabin barometer, are suspended — in a 
sort of universal joint, commonly called jimbals. The idea of 
suspending a cabin in this way is no novelty ; but there were 
several practical difficulties in the way of carrying it out on a 
large scale. The double pivoting makes rather an insecure 
connection between the large moving weight and the structure 
of the ship. There are also difficulties about getting in and 
out of such a cabin. Moreover, there is no really fixed point 
in a ship at sea, and the motion of the point of suspension 
reacts upon the suspended mass, which thus acquires an oscilla- 
tion of its own. Oscillations have a regular rhythmical 
period, like a musical note, and every freely suspended body 
has its own note, or periodic time. If it happens that the 
periodic time of the suspended cabin coincides, absolutely or 
approximately, with that of the point of suspension, there may 
be an accumulated roll far in excess of that of the ship itself. 
A freely suspended cabin, therefore, would not answer the in- 
tended purpose. 
The point of Mr. Bessemer’s invention consists in the steady- 
ing of the cabin being controlled by hand instead of acting 
