ago Mr. lan den’s new Theory of 
2. The particle p being connedted with the plane 
doefqg as mentioned in the preceding article, and the 
diftance c/ being denoted by v; if p be urged diredtly 
from the faid plane by a force/# x />, the efficacy -of that 
force to turn the faid plane about the line hci, therein ; 
drawn at right angles to ocq_, will (by th'e property of the 
lever) be equivalent to the force adting on the 
faid line occyat right angles to tire faid' plane at the dif- 
tance g from the point c. 
Moreover it is obvious, that, cceteris paribus , the effi- 
cacy will be. the fame let the diftance of q from / be what 
it will. 
Fig. 10. Let q coincide with /; and let be a line 
in the plane c/p continued (which plane will be at right 
angles to the plane doefqg) ; alio, pk being at right an- 
gles to c k y let thofe lines p k and c k be denoted by w and 
x reflectively. Then the fine and cofine of the angle 
kco to the radius i, being refpedtively denoted by m and 
the force d — will be = — x«kx^ 2 -x‘ ^wk—T^wx. 
Confequently, if each particle of any folid body, through 
which a line hci and a plain doeifqgh may be conceived 
to pafs, be urged from that plane by a force expreffed by 
fuxp as above; the force which, adting on the line 
oco_at the diftance g from c, would be equivalent to the 
efficacy 
