Henry Gray (18251861). Anatomy of the Human Body. 1918.
If the second muscle likewise shortens 5 mm. then E f = E F 5 mm., and with the tension of 1000 gms. the bone J B1 will take the position J B3 and the weight or load (L1) will be lifted from H1 to H3. The question now is to prove that the work done is the same in both cases, namely, 5 x 1000 grammillimeters. If so, 400 x H1H2 = 230 x H1H3 = 5000 grammillimeters.
Since the two radii C d and C d are very long as compared with the arc d d we may consider this short arc as a line \??\ to C D at d, likewise the arc f f may be considered as a straight line \??\ to E F. In the same manner we can consider the short arcs F f, D d, H1H2 and H1H3 \??\ to the line J B1. The sides D d and F f of the Δ D d d and F f f are each 5 mm.