1894.] ^^'^ [Brche. 



tion of acquired velocity, or what is otherwise known as accelera- 

 tion, due to terrestrial gravity. I am merely putting the two equals, 

 as derived from different sources of power, in juxtaposition, so as 

 to compare and contrast them with each other,. and thus to bring 

 clearly before the mind that it is not likely that any boxer's blow 

 can have a speed essentially greater than that represented by the 

 acceleration due to gravity in half a second, or, in other words, the 

 rate of 16 feet per second. Terrestrial gravity would, as indicated, 

 have nothing to do with the force of the resultant blow. The blow 

 being horizontal, the force of gravity with relation to it would be 

 virtually ////. The statement here is limited strictly to the fact that 

 if the boxer can strike 4 feet in a quarter of a second, he can strike 

 that distance with the momentum that would be generated by grav- 

 ity in one-half of a second, acting on any mass subjected to it from 

 a state of rest. 



The fact must be kept constantly in view that mass and velocity 

 combined make momentum. With enormous weight and great 

 slowness, the effect produced is not of the nature of a blow, but that 

 of a push. With great velocity and minute weight, the blow pro- 

 duced is slight. With both great weight and great velocity, the 

 blow becomes tremendous. Here it is well to add that the popular 

 notion of the amount of his weight that a man can put into a push 

 or a blow is highly erroneous. Mechanical engineers, who are con- 

 tinually obliged to make computations for the deployment of the 

 force of pushing on capstan-bars for drawbridges and other places, 

 know that, unless there are cleats on the ground from which the feet 

 can obtain some purchase, from 15 to 20 pounds is about the proper 

 amount to allow for the push of a man working under those condi- 

 tions. The question therefore remains open in every individual 

 case, unless instrumentally settled, as to what proportion of the mass 

 of the boxer of 190 pounds enters into his blow, and this, with dif- 

 ferent men, varies as well as the speed. But supposing, for the sake 

 of argument and demonstration, what has already been rejected, that 

 the whole weight of the man enters into the blow, its momentum 

 for 4 feet, at the rate indicated, would be represented by 190 

 pounds multiplied by 16, or the rate of speed, at the half-second 

 point, due to the force of gravity for a first second, and would be, 

 as already noted, 3040 pounds. A man cannot, however, as already 

 stated, put his whole mass info a blow, because he cannot, by any 

 muscular effort whatsoever, move freely in space. The indispen- 



PROC. AMER. PHILOS. SOC. XXXIII. 145. X. PRINTED MAY 26, 1894. 



