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wc have assumed, that part is exposed. Taking as an 
example a vessel of 300 feet in length, built some years ago, 
I found that she would have given way with four-fifths of the 
actual displacement of herself and cargo. Taking a vessel 
constructed according to Lloyd’s last rules, and registered 
A 1 for twelve years, I found her still inadequate to sustain 
the stress to which she would inevitably be exposed in such a 
position, the weak part being still the upper deck. I am 
therefore forced to the conclusion, that a large increase in the 
sectional area of iron in the upper part of the vessel should 
be adopted ; and the plan I have proposed consists in the 
introduction of two rectangular and two triangular cells of 
wrought iron (similar in principle to those in the Britannia 
and Conway tubular bridges), placed longitudinally under the 
upper deck of the ship. Cells of this form would increase 
enormously the strength of that part, and might be adopted 
without any great modification of the other arrangements of 
the ship. 
In the second place, I am led to recommend the substitu- 
tion of the new system of chain rivetting along the decks and 
upper and lower portions of the sheathing, in place of the 
present weak plan of double rivetting. This change alone 
would secure an increase of thirty per cent, in the power to 
resist tension in those parts ; and although there are practical 
difficulties in the way of its adoption, 1 believe these may, to 
a great extent, be overcome. 
Now, in looking at the principles on which iron ships have 
been constructed, it will be found that sufficient attention has 
not been paid to proportioning every part to the strain it has 
to bear. As now constructed, the iron is distributed almost 
uniformly throughout the length and uniformly throughout 
the depth of the vessel, and in this way much material is 
wasted. In constructions which have to resist transverse 
strains, economy can only be obtained by collecting the 
material towards the top and bottom in the transverse vertical 
