1.16 OUTLINES OF NATURAL PHILOSOPHY. 



h and I to be variable, the other quantities being 

 constant, the locus of the equation is a hyperbola, 

 which may be easily constructed. 



The theorems just given only differ from COULOMB'S, by 

 being somewhat simpler, and free from all reference 

 to any particular measure of length or of weight. 



On the subject of Animal Force, however, many more 

 experiments are wanting : to determine, for instance, 

 the friction of wheel carriages ; the difference be- 

 tween the exertions required to walk on a horizontal 

 plane, and on one of a given declivity ; the quantity 

 of work done in a given time by the same animal, 

 carrying different loads ; the difference between 

 the effective exertion of a man's strength when he 

 moves along with his load, and when he stands, as 

 in turning a wheel, or sits, as in rowing a boat, 

 Sec. &c. 



SECT. V. 



MOTION OF MACHINES. 



185. JM.ACHINES either work with a variable 

 or a uniform velocity. If the moving power is of 

 the kind that, when the motion begins, diminishes 

 in the intensity of its action, the machine, after 

 a little time, will acquire a uniform velocity. 



If, 



