[ 2 9 * ] 
inches ; and the trough was exa&ly levelled, by- 
means of the pencil-line, at 5 inches : then the 
block being forced under the water’s furface, the 
fluid, when ftill, was rifen to 6 7 inches j confe- 
quently the magnitude of the block was equal to a 
parallelopipedon of 46 inches long, 14 inches broad, 
and 1 7 inches deep, or to 858 -§ cubic inches. 
Now 8y8f cubic inches are equal to 0.4965? cubic 
feet. 
And a cubic foot of fea-water weighs 64.3732 
pounds avoirdupoize. 
Then 64.3732x0.4969=31.987 pounds. 
So that by a quarter inch fcale, a model fimilar to 
the Royal William weighs near 3 2 ife. 
But a quarter inch fcale is 77 of a foot fcale. 
And the model is to the {hip as "? 3 is to 4P 5 , or 
as 1 is to 110592. 
Then 3537fo6ib (=110592x31.98 7), or 1779 
tons, 4 C. 3 qrs. 14 jfc>. is the weight fought. 
The difference by the two methods amounts to 
,5415 lb- or to 2 tons, 8 C. 1 qr. 1 1 ib. 
Some of the perfons prefent at this experiment 
read the height of the water at 6 j inches : the dif- 
ference between 6 f and 6 7 inches is Ar of an inch ; 
a difference eaflly to be made by different perfons in 
an experiment of this kind. But obferving, that the 
computation made on 6 •§ inches amounted to near 
yo tons more than on 6 7 inches, I caufed the trough 
to be diminifhed in its depth to 67 inches, had 
one of the ends cut off, and a board fixed on the 
open fide, being defirous of making the experiment 
with the trough {landing on one end : and indeed, 
in this fituation, an error of — of an inch in the 
P p 2 height 
