Of GREATEST ATTRACTION. 231 
In the fame manner, 
Ltan (48° +8) = 0.0455626 + .0c002540 £, 
and L. coverf. (48° + 8) = 9.4096883 — .0003292 B 
L3-= 0.4771213 
Sum = 9.9323722 — .0000752 6B 
Subtract Log arc (48° +8) = 9.9231186 + .o001506 8 
Remainder = .0092536 — .0002258 B=o. 
— 92536 _ yy 
Whence, 6 = ce ag 41’ nearly. 
A SECOND approximation will give a correction = — 20’, 
fo that ~ = arc . 48°. 40’ os and fince fing = fing’, fing — 
N fin g, fo that 7 => 76°. 30’, and 2, or the whole angle of the 
pyramid = 153°. 
An ifofecles pyramid, therefore, with a fquare bafe, will at- 
tract a particle at its vertex with greateft force, when the in- 
clination of the oppofite planes to one another is an angle of 
153°. 
XX. 
To return to the attraction of the parallelepiped, it may be 
remarked, that the theorem concerning this attraction already 
inveftigated, § xvi11. though it applies only to the cafe when 
the parallelepiped is indefinitely thin, leads, neverthelefs, to fome 
very general conclufions. It was fhewn, that the attra@tion 
which the folid EL (Fig. 11.) exerts on the particle A, in the di- 
rection AB, is 7.9, @ being an arch, fuch that fing = fin BAC 
x fin BAL = fin z.fin E; and, therefore, if B be the centre of 
a 
