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fully fatisfied to what degree of exadhiefs it can be 
made to anfwer the end propofed. I am, 
Jure 4, 1752, 
Gentlemen, 
Your moil obedient 
humble fervant, 
J. Ellicott. 
LXXXII. A Defer iption of a new Tackle or 
Combination of Pullies, by Mr. J. Smeaton. 
Read June 1 I I E axis in periirochio , and the com- 
1752 X pound pulley, are the only mecha- 
nic powers, which can with convenience be applied 
to the moving large weights, when the height, to 
which they are intended to be railed, is conliderable. 
The excellence of the former is, their working with 
little fridtion ; that of the latter, in their being eafy 
to be moved from place to place, and applied ex- 
tempore, as occafion requires. 
The prefent methods of arranging pullies in their 
blocks may be reduced to two. The firft confifts in 
placing them one by the fide of another upon the 
fame pin ; the other in placing them diredtly under 
one another, upon feparate pins. But in each of thefe 
methods an inconvenience arifes, if above 3 pullies 
are framed in one block. For, according to the firft 
method, if above 3 pullies are placed by the fide of 
caie another, as the laft line, by which the draught 
is 
