WEIGHT AND SUPPORT IN SHIPS. 
433 
curves for which ships are marked MM in Plate XVII. figs. 8, 9, 10, & 11 respectively. 
In all cases the same scales for lengths and for moments have been nsed, so that a lair 
idea of the relative conditions of strain can he obtained from a comparison of the diagrams, 
and the scales employed are marked on the various plates. Hereafter I shall refer at 
some length to the comparative strains of these ships, but will first refer to a few 
general considerations respecting vertical bending-strains, using the preceding cases as 
illustrations. 
The simplest case is obviously that of a ship which, like the ‘ Minotaur,’ is subject to 
hogging-moments at every transverse section, these moments gradually increasing in 
amount from the extremities towards the middle of the length, and attaining their maxi- 
mum value near the midship section, as shown by the curve M M in Plate XVII. fig. 8. 
Earlier writers, as I have shown, regarded this as the only case which deserved attention ; 
and recent works on the strains of ships devote greater attention to it than to any other case 
of strain, doubtless with good reason, since it is that which is most commonly met with. 
Modern writers, however, have also clearly pointed out the possibility of sagging- as well 
as hogging-strains being experienced by ships when floating in still water, and have laid 
clown the conditions which must be fulfilled in such cases. But while this is true, it is 
no less true that a very general belief exists among shipbuilders and others that where 
an excess of weight over buoyancy exists at the middle of a ship’s length there must 
necessarily be sagging-moments; and in some published works on the subject this is 
laid down as a general rule. No better illustration of the error of this belief could, I 
think, be given than that afforded by the ‘ Bellerophon,’ which has an excess of weight 
over buoyancy amounting to 250 tons at the middle, and yet no sagging-strains at any 
portion of her length. The curve M M in Plate XVII. fig. 9 shows that this is so ; and 
at the section of minimum hogging-moment, b , there is a strain of about 100 foot-tons. 
The case of the ‘Audacious’ in Plate XVII. fig. 10 furnishes another illustration of the 
same kind. In her the excess of weight amidships, when fully laden, amounts to 265 
tons ; but the bending-moment, so far from becoming a sagging- strain, never falls below 
a hogging-strain of 3400 foot-tons. 
Cases do undoubtedly exist, however, in which great excesses of weight amidships 
produce sagging-moments in still water, and of these we have an example in the ‘ Vic- 
toria and Albert.’ On reference to Plate XVI. fig. 7 it will be seen that in this ship the 
central part of the curve M M falls below the axis, thus indicating the fact that about 
30 feet of the midships length of the ship is subjected to a very small sagging-moment, of 
which the maximum value does not exceed 170 foot- tons, although the excess of weight 
over buoyancy amounts to 210 tons. A very small deduction from this excess of weight 
would suffice also to convert this sagging-moment into a small hogging-moment. For 
example, suppose 10 tons only to be taken from the excess, and a weight of 4 tons to be 
placed 150 feet before the position from which the 10 tons were taken, while the re- 
maining 6 tons are placed 100 feet abaft it. The trim of the ship would remain unal- 
tered, and the distribution of buoyancy would therefore be unchanged ; but the removal 
