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The v 2 ( *JlA — s sAx — ?. = s s Ax T *_ => 
\ i? R J 
ssAx\ ; radius being 10. 
Or the log. v 2 A — 2 log. sA — log. y. 
But when radius is 10, the line of 30° is f. 
Therefore the log. v 2 A = 2 log. i — log. fine 
of 30°. 
Moft of the writers on this fubjedt give the follow- 
ing rule for laying down the divilions of this line : 
From the line of logarithmic fines, take the di- 
flance between 90 u and any arc ; that diftance 
being twice repeated, from the termination of 
the line of verfed fines, will give the divifion 
for twice the complement of that arc.” 
Thus the difiance between 90° and ao° on the 
fines twice repeated, gives the verfed fine of 140° ; 
or twice 70°, the complement of 20°. For the di- 
vifions, to be laid on this line, are the differences be- 
tween the logarithm verfed fine of 1 8o°, and the 
logarithm verfed fines of the fucceflive arcs. 
Now the difference between the logarithm verfed 
fines of 180 0 , and of any arc 2 A , is log. ver. fine 
180 — 2 log. fin. A + log. fin. of 30°. 
Or, 10,30103 -|~ 9,69897 — twice log. fin. of A. 
Or, 20,00000 — twice logarithm fine of A . 
Or the arithmetical complement of twice logarithm 
fine of A. 
That is, the difference between the logarithm verfed 
fine of 180 0 , and the logarithm verfed fine of any 
arc, is equal to double the arithmetical complement 
of 
