[ 497 ] 
raifed 600 weight. But with a tackle of this fort, 
properly executed in large, one man will eafily raife 
2. ton, and a greater number in proportion 
I have tried feveral numbers of fhieves as far as 3 6 ; 
but 20 feems to be the larged; number, that will an- 
fwer well in practice. 
A very commodious tackle of 12 might be exe- 
cuted in wood, in the fame manner that common 
blocks are made. 
I fhould not have troubled the Royal Society with 
an account of this contrivance, did it not feem pro- 
mifing of much utility, in a variety of purpofes; par- 
ticularly for merchants, feamen, builders, engineers, 
&c. I therefore intirely fubmit it to the cenfure of 
tliat honourable body. 
J. Smeaton. 
i P. &. In conftru&ing a tackle of 20 for 3 tons, the 
larger tier of fhieves fhould not be lefs than S 
inches, the running line needs not be thicker than 
half an inch diameter, and the iron pins need 
not be fo thick. 
* A large tackle of 20 was tried on board one of his Majefty’s 
{hips ; and by the help thereof, tho’ it was with a new rope, one 
man raifed one of the fhip*guns and carriage, that together weighed 
27 hundred -weight ; there being a perfon, as ufual, to bold on , or 
prevent the rope from flipping back. 
R r r 
LXXXIII. 
