6 
Mr. Seppings on the great strength given to 
system in the diagonal frame, been placed in the same direc- 
tion that those in this experiment were that are marked A, 
the ships so constructed would, in the act of launching, 
pitching in a sea, and as they grew old, have slackened cer- 
tain parts of the diagonal frame, and the fabric would have 
been supported by long crooked trusses , whose ends would have 
had but one point of support, namely, the shelf piece or 
internal hoop ; and what is more objectionable, the ends of 
the trusses would, if so placed, have been cut off to an angle 
of 45 0 . On the contrary, by making the ties in the diagonal 
frame the abutments, as many additional points of support 
are gained, as the trusses B exceed the braces A ; and further, 
the trusses B are now straight and short, and their ends are 
cut off to a right angle, and thereby give a support, and the 
longitudinal pieces a fixedness, which would not have been 
the case had they been laid in the other direction. 
Indeed no stronger proof could be adduced in favour of the 
efficacy of the principle, than that which was furnished in the 
launching of three ships of 120 guns (the Nelson, the St. 
Vincent, and the Howe). In form and dimensions these three 
ships are precisely the same, and their frames, beams, and 
external planking, of the same scantlings : the two former 
were built according to the old plan, and the latter upon the 
diagonal system. After the Nelson was launched, she was 
found to have altered nine inches and a half from her original 
sheer, and the St. Vincent nine inches and a quarter, while 
the Howe altered only three inches and five eighths. The 
whole machine in the case of the two former ships was 
generally disturbed ; the Howe exhibited no such symptoms. 
I shall only further state, that after the memorable battle 
