WEIGHT AND SUPPOET IN SHIPS. 
441 
fineness of the entrances of the two ships, and the change from the V-form to the U-form 
of transverse section. At the sterns of these ships there is also a remarkable contrast 
between the bending-moments tending to break off the overweighted parts, although not 
so great as that at the bows, on account of the absolute necessity for fineness of form 
in the run of the ‘Minotaur;’ the bending-moment at the aftermost water-borne section 
(K 2 in Plate XVII. fig. 8) is upwards of 20,000 foot-tons, while at the corresponding 
station in the ‘ Bellerophon ’ it is only about 7000 foot-tons. These strains on the stern, 
unavoidable as they are, to some extent often develope weakness in screw steam-ships. 
With respect to the bending-moments experienced by the foremost and aftermost water- 
borne sections of the ‘ Victoria and Albert ’ and of the ‘ Invincible ’ nothing need be 
said ; the curves of moments for these ships are constructed on the same scale as those 
for the other two, and the lengths of the ordinates afford the means of comparing the 
strains at various parts. 
Before concluding my remarks on the still-water strains of ships, I must refer to 
another cause of bending to which brief allusion has already been made, viz. the hori- 
zontal longitudinal fluid pressure on the immersed part of a ship. The most recent 
writers on the subject have not taken account of this cause of bending, doubtless because 
they considered its effect out of all comparison with the effect produced by the vertical 
forces, an opinion which the greater number of earlier writers also entertained. Euler 
and Dr. Young were exceptions, as I have shown ; and the following results will prove 
that they were justified in attaching importance to the effect of the fluid pressure, 
although they did not correctly estimate it. Without criticizing their methods, how- 
ever, I will proceed to indicate a simple plan for estimating the amount, and the bending- 
moment, of this pressure at any transverse section of a ship afloat in still water. 
According to a well-established hydrostatical law, the resultant fluid pressure, in a hori- 
zontal direction, on a solid immersed in it equals the pressure of the fluid on the pro- 
jection of the surface of the solid upon a plane at right angles to that direction; and 
this resultant acts through the centre of pressure of the plane area. Applying this 
principle to a ship, we see that the longitudinal pressure upon any part bounded by a 
transverse section equals the pressure upon the immersed area of that transverse section, 
and acts through the centre of pressure of the immersed area. By this means, therefore, 
we can determine the amount and the line of action of the resultant longitudinal pressure 
upon the parts of a ship, either towards the bow or towards the stern, cut off by a trans- 
verse section ; and knowing these two features, we can determine the moment of the 
pressure about any horizontal line in the transverse section. For our present purpose 
it will suffice to say that the line about which moments must be taken in order to 
determine the bending effect produced by the pressure at the section coincides with the 
ecntre of gravity of the section*. Assuming that we know its position, and knowing 
* It may be interesting to state here that Euler’s mistake respecting the action of this longitudinal pressure 
arose from the fact that he considered the lower side of the keel as the “ fulcrum,” as it was then termed, about 
which moments should be taken. 
