[ 2i6 ] 
by any. of the -natural numbers, for inftance by lo, 
the quotient 3660, ftanding among the Tabular dif- 
.ferences (in Tables for each minute) at 21° : 50' and 
68°: 10',. fhews that when the value of ECP in 
the table already made, is either 21°: 50 or 68° : 10.', 
JO minutes muft be fubtrafted to adapt it to the lever 
whofe femi- angle is only 84° ; and fo of the reft. 
The greateft.difference of the inclination of the in- 
dex will be when ECP is, 45° : the Tabular differ- 
ences being, then the leaft. All this is not indeed ^ 
quite accurate, but fufficiently fo for pradtice. 
To find accurately when this difference is greatefl, 
and what that greateft difference is ; add (or fubtradl 
as the cafe requires) half the difference of the Loga- 
rithmic Tangents of the femi-angles aforefaid, to the 
Logarithmic Radius, and it will give the Logarithmic 
Tangent of ECP, in that cafe j and the difference 
between ECP thus found, and its complement, is 
the greateft difference fought. Thus half 36,608 
added to lo.ooooooo is 10.001 8304, the Log. Tan- * 
gent of 45° ; 7' ; 14' ',4, the inclination. of the in- 
dex, when its change by reducing the femi-angle of 
the lever to 84°, is greateft, and the quantity of that'; 
change is 14' : 28", 8, 
• A. Table 
