256 OBSERVATIONS 
that of the ftill more oblique pair of mufcles reprefented in 
the fame figure by the lines 1D and 1E. Let the mufcles 
AD and AE be fuppofed to move the point Ato number 1, 
and let the mufcles 1 D and 1E be fuppofed to move number 1 
to number 2, or through a like fpace. It is evident, that in 
the triangles 1 1 E and 211 E, the angles 11 Eand 2I1E are 
equal; but as the angle 2E II is larger than the angle 1 El, 
the angle II 2 E muft be lefs than the angle 11 E. Hence, as 
the fides of triangles are longer in proportion to the width of 
the oppofite angles, the fide IE will be longer in proportion 
to 1 E, than the fide ILE is in proportionto 2E, The muf 
cular fibres, therefore, AD and AE, in bringing the point A 
down to number 1, will lofe more, in proportion of their 
length, than the more oblique fibres 1 D and 1 E will do in 
moving number 1 to number 2. 
To prove this by calculation, let us fuppofe the mufcle to 
be ftill reprefented ‘by the hypotenufe of a right angled tri- 
angle, five inches in length, and capable of fhortening itfelf 
one inch, and that one of the other fides meafures four inches, 
and that the third fide meafures three inches. But let the fide 
3 form the bafis of the triangle, and the fide 4 its perpendi- 
cular, as in T. 2. fig. 7. 
In this cafe, the fquare of the hypotenufe, when it has 
fhortened itfelf one inch, will be 16, from which dedudting 9, 
the {quare of the bafis, the number 7 remains for the {quare 
of the perpendicular. But the fquare root of that number 
being more than 24, the oblique mufcles, fhortened one-fifth, 
cannot bring the point A down 14 inch, or to B, or cannot 
move the point A half fo far as they were fhewn to do, when 
the obliquity was greater, by making the bafis 4 inches and 
the altitude 3 inches. 
Or let us, on the other hand, increafe the obliquity, as in 
T. 2. fig. 8. by fuppofing two right-angled triangles, fo con- 
2 ; ftructed 
