Bache.] 1"* [May i, 



sable condition of his being able to deliver an effective blow is that 

 he shall be, as to his feet, poised on the surface of the earth. So 

 unless, by means of electrical recording apparatus, we determine 

 the speed of a blow, and, by means of a dynamometer, determine 

 the moving energy of it, and deduct one value from the other, we 

 cannot ascertain how much of the effectiveness of a blow is owing 

 to the weight of the human body thrown into it, and how much is 

 derived from a speed which involves the whole person — hand, arm, 

 and trunk. 



It would follow, from all the evidence at my command, that if 

 the speed of a blow of four feet be a quarter of a second, a man of 

 even 190 pounds in weight cannot follow up, so as to make effective 

 in his blow, with more than 32 pounds (in round numbers, a sixth 

 of his weight) with velocity equal to free movement of fall of a 

 mass for the first half-second, from a state of rest, above the surface 

 of the earth. Barrett, the late well-known teacher of boxing in 

 Philadelphia, a man of undoubted veracity, as highly esteemed in 

 his day and limited sphere as was, at the beginning of this cen- 

 tury, in a more extended one. Gentleman Jackson, of England, 

 Byron's boxing master, once told me as remarkable that he knew 

 a man who could strike 500 pounds. This meant, of course, as 

 tested by a dynamometer. If then, in fine, the time of a boxer's 

 blow be a quarter of a second, the length 4 feet (which would 

 make, as already remarked, the rate the same as that due to the 

 effect of gravity on a mass in the first half second, fallen from a 

 state of rest), and the proportion of his weight accompanying it be 

 32 pounds, he would strike with the momentum represented by 32 

 pounds multiplied by 16, or 512 pounds. This momentum, if the 

 reader experienced in boxing will consider the speed here ascribed 

 to the blow of the finest boxer, and the confirmatory evidence de- 

 rived from the statement of Barrett, would seem to be very near 

 the mark. No one will be likely to maintain, after what has been 

 said, the possibility of striking an effective blow of 4 feet in length 

 in less than a quarter of a second ; or that, of the weight of a man 

 of 190 pounds, more than 32 of them can be put into a blow cor- 

 responding vvith the rate of 16 feet per second. 



Up to the point we have reached the conclusions drawn were partly 

 dependent upon an estimated velocity of blow, derived from observa- 

 tion, not experiment. But a friend having reminded me that, among 

 Mr. Muybridge's series of photographs of movements of man and 



