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On the great Strength given to Ships of War by the application of 

 Diagonal Braces. By Robert Seppings, Esq. F.R.S. Read No- 

 vember 27, 1817. [Phil. Trans. 1818,^. 1.] 



The principle of applying diagonal frame- work to ships of war 

 was first partially and successfully adopted in the Kent, of 74 guns, 

 in the year 1805, and since that period has been successfully em- 

 ployed in the construction of thirty-eight sail of the line and thirty 

 frigates. These circumstances might be deemed conclusive as to the 

 advantages of the new system ; but as the Royal Society have 

 already published this author's account of it at a very early period 

 of its adoption, he is induced to offer the result of a new experiment 

 in proof of the correctness of the principles before laid down, which, 

 as far as his knowledge extends, has never been previously applied, 

 nor ever suggested by any continental writer, though, says the author, 

 it has been pretty broadly insinuated that the hint was borrowed from 

 the French. 



In the early part of the present year, the Justitia, an old 74, was 

 ordered to be broken up ; when Mr. Seppings, notwithstanding her 

 shattered condition, determined to apply the trussing principle. 

 Prior to her being taken into dock, sights were placed in the lower 

 and upper gun-deck, to ascertain, when she had grounded on the 

 blocks, how much she deviated from her state afloat. She was then 

 partially trussed, as described by reference to an annexed drawing, 

 and floated out into the basin. After lying one hour, it was found, 

 by the sights placed on the gun-deck, that she had come down in 

 the mid-ship 1 foot ; and by those on the upper-deck, 1 foot 2$ 

 inches. In twenty-four hours she further hogged 2 inches, and then 

 appeared stationary. The trusses in the hold were then removed, and 

 she further hogged 6 inches, and 3-J- inches in removing those in the 

 ports. 



In further illustration of the efficiency of the principle, Mr. Sep- 

 pings adduces the Nelson, St. Vincent, and Howe, three 120- gun 

 ships of the same dimensions ; the two former built upon the old 

 plan, the latter upon the diagonal system. The Nelson, after she 

 was launched, altered 9^- inches from the original sheer, the St. Vin- 

 cent 9-^, and the Howe only 3| inches. 



The paper concludes with a very favourable report from Captain 

 Coode, of the state of His Majesty's ship the Albion, after the memo- 

 rable battle of Algiers, which, in his opinion, stood the concussion 

 from the firing better than would have been the case had she not 

 been constructed on the diagonal plan ; and with an account of the 

 deck of the Northumberland, which was laid on one side fore and aft 

 as usual, and on the other side diagonally, the materials on each 

 side being similar. After her return from St. Helena, the officers of 

 the Sheerness yard, who were directed to examine her, reported, that 

 having examined the state of the decks and waterways, they found 

 the comparison so much in favour of the larboard side, as to deter- 

 mine in favour of the diagonal system. 



