1874.] Loss of Life at Sea. 479 
The more rapidly the wave is moving, the greater is the 
difference between the motions of the upper and lower 
particles ; therefore the higher up is the lateral thrust, and 
the danger greater from a high centre of gravity. 
It may be said that, in lowering the centre of gravity, the 
point round which the ship turns will be changed, and 
therefore c’ will not occupy the same place under the altered 
conditions. ‘This is true, but the fact is in favour of our 
argument, for, in proportion as the centre of gravity is low, 
the radius will be shorter, c’ therefore will be moved out a 
less distance, and the injurious influence of the wave motion 
will be proportionably less. 
To assume, therefore, that the metacentric height is a 
measure of the disturbing force is erroneous. 
It is indispensable for a ship’s safety, as it also is for her 
complete efficiency, that she should possess a considerable 
metacentric height ; then to reduce this by raising the centre 
of gravity, under an impression that the arcs of roll will be 
reduced, is erroneous and an unmixed evil. 
It ts not true, as stated by Mr. Froude, that ‘‘the effort of 
stability is the lever by which a wave forces a ship into 
motion. Ifa ship were destitute of this stability, no wave 
that the ocean produces would serve to put her in motion, 
whether the stability be due to deeply stored ballast or to a 
broad plane of flotation.” 
If, however, the metacentric height is made unduly high 
by great proportionate breadth, or by placing a cargo of 
metal on the ship’s floor, then the motions will be too rapid, 
though short, in which case the evil may be got rid of, with 
benefit and without danger, by raising the centre of gravity. 
But still there is a minimum of metacentric height, below 
which it cannot be reduced with safety. 
Ships must yield to the waves, and all arrangements and 
designs should be to facilitate their doing so slowly and 
equably. The effect of Mr. Froude’s plan is to put off the 
inclination till the wave accumulates in such force that it will 
sweep the decks, force the ship over suddenly, and possibly 
overturn her, if she be not previously “‘swamped.” 
Therefore the metacentric height, or the distance of the 
centre of gravity from the metacentre, must not be taken as 
giving the measure of the disturbing force, for in lowering 
the centre of gravity the metacentric height is increased, 
but we have seen that in proportion as the centre of 
gravity is lowered so the disturbing action and extent 
of motion is limited; and therefore the proposition to 
raise the centre of gravity, with a view to reduce a ship’s 
