696 REPORT— 1863. 
ought not to use plating in any vessel, however large, more than about three- 
quarters of an inch thick. 
In the early period of iron shipbuilding the frames were generally com- 
posed of simple bars of angle-iron, but they are now usually doubled by a 
reverse bar, which is riveted on the principal bar, so as to make a frame 
whose cross section is like the letter Z, and this form is perhaps as strong as 
any that could with economy be obtained. In some large ships, plates of iron 
on edge were placed between the angle-irons so as to enlarge the section. 
The frame thus formed required longitudinal supports to bind it together, 
and those all-important strengthening pieces, called stringers, box and other 
keelsons were introduced. The great advantage of these appliances is, that 
they may be placed exactly where the ship requires support, and that, too, 
with the least possible amount of iron. As to the application of these 
stringers and keelsons, the shipbuilder must be guided by the form, propor- 
tions, and other circumstances connected with the construction of the ship. 
To show how far this system of longitudinal framing may be carried with 
success, I may point to the ship ‘ Richard Cobden,’ designed by Mr. Guppy (known 
in connexion with the construction of the ‘Great Britain’) in 1844. This 
vessel was framed so as to leave rectangular spaces to be covered with the 
outside plating; these spaces were 23 feet vertically, and 5 and 6 feet 
horizontally, and in no part of this highly successful construction were the 
plates more than sths thick. 
As to the riveting, which is of the utmost importance in shipbuilding, I 
shall say a few words. In making boilers, single riveting is usually adopted, 
but there the strain is constantly in one direction. In ships the direction of 
the strain is changeable as the vessel moves ; therefore double, and in some 
cases triple riveting has been used with great advantage. Mr. Fairbairn 
estimates that the tensile effect of single riveting is represented by 56, 
double riveting by 70, and triple riveting by 90, and these proportions 
would appear to hold good whether in chain or zigzag riveting. The former, 
however, has been shown by experiment to have an advantage over the latter 
of about 20 per cent. in the tensile strain. 
In concluding this necessarily brief account of the general principle on 
which iron ships are constructed, I may mention that the only objections 
that can reasonably be urged against ships made of this material, are that the 
compasses are difficult of adjustment, and that the bottoms get foul. Let us, 
however, hope that science, in the promotion of which the British Association 
is so powerful an agent, may in a short time show us how both these diffi- 
eulties may be overcome. 
I now proceed to what is perhaps the more interesting division of this 
paper, viz., a sketch of the progress of iron shipbuilding on the Tyne, Wear, 
and Tees. 
For a very long period the district of the Tyne, Wear, and Tees has been 
famous for its shipping. A committee of the House of Commons, that sat 
so far back as the year 1642, designated Newcastle as “the nursery for 
shipping,” and Defoe, writing of the Tyne in 1727, states that “they build 
ships here to perfection—I mean as to strength and firmness, and to bear 
the sea.” 
The history of iron shipbuilding in this district does not commence, how- 
ever, until the year 1840. In March of that year, the ‘John Garrow,’ of 
Liverpool, a vessel of 800 tons burthen, the first iron ship seen in these rivers, 
arrived at Shields, and caused considerable excitement. A shipbuilding 
firm at Walker commenced to use the new material almost immediately, and 
