ON THE MAXIMUM DIMENSIONS OF SHIPS. II 
The Mauretania has averaged for a whole year, on 30 consecutive 
passages (15 voyages) westward and eastward, in all weathers and under 
varying and uncontrollable conditions of service, a mean speed of 25.5 
knots. The highest mean speed going west was 26.06 knots; coming east 
it was 25.89 knots; the lowest mean speed was 24.92 knots in both directions. 
This regularity of performance has been repeated during service in two 
following years, the average mean speed being 25.25 knots and 25.1 knots 
respectively. In the series of passages made between February and August 
this year; the total number of revolutions of the screws during each passage 
varied only two per cent. above or below the number of revolutions per 
passage deduced from an average for all the passages. These figures may 
be left to speak for themselves. A closer approach to regularity of perform- 
ance on the Trans-Atlantic service can hardly be realized whatever may be 
the sizes of the ships employed. 
Experience proves also that in the Cunarders the limit of speed at which 
they can be safely driven in heavy seas is not fixed by their size, engine 
power, or general structural strength, but by considerations of the serious 
damage which might be done to fittings and navigational appliances as well 
as to the officers and crewemployed in navigating the ships, and of the safety 
of passengers if the ships were driven at high speed against heavy seas. No 
prudent commanding officer is likely to incur unnecessary risks in these 
directions; and so there comes a time when the vessels are not driven 
at full speed against heavy seas but are slowed down until the weather 
moderates. ‘This will always remain true whatever the sizes of ships may be. 
In regard to steadiness in a seaway, long experience has shown that 
ships of less size may be more free from heavy rolling in a seaway than much 
larger ships, if the latter are endowed with greater stiffness and consequently 
move more quickly when rolling. Speaking on the basis of numerous per- 
sonal observations made on ocean voyages, I can testify that this is the fact 
both for merchant ships and for warships. In recent years increase in the 
proportion of breadth to draught of water has tended to shorten periods of 
oscillation. No doubt in modern passenger steamers the lofty superstruc- 
tures tend to raise the center of gravity and so to diminish stiffness and 
lengthen periods of oscillation. The increased breadth of ships has also 
tended to lessen the “effective wave-slope,’ and so to diminish rolling. 
Apart from detailed calculation no exact knowledge can be reached respect- 
ing the probable behavior and period of oscillation for a new ship; but that 
fact in no way contradicts the general statement made above, that large 
dimensions are not necessary to secure moderate rolling and easy motion. 
In modern warships of the largest types, as I pointed out in the paper read 
