FEATS OF ECKEBERG. 253 



were a thin piece of iron, or even two or three 

 times heavier than the hammer, the performer 

 would be killed by a few blows ; but the blows 

 are scarcely felt when the anvil is very heavy, for 

 the more matter the anvil has, the greater is its 

 inertia, and it is the less liable to be struck out 

 of its place ; for when it has received by the blow 

 the whole momentum of the hammer, its velocity 

 will be so much less than that of the hammer, as 

 its quantity of matter is greater. When the blow, 

 indeed, is struck, the man feels less of the weight 

 of the anvil than he did before, because in the 

 reaction of the stone all the parts of it round 

 about the hammer rise towards the blow. This 

 property is illustrated by the well-known experi- 

 ment of laying a stick with its ends upon two 

 drinking-glasses full of water, and striking the 

 stick downwards in the middle with an iron bar. 

 The stick will in this case be broken without 

 breaking the glasses or spilling the water. But 

 if the stick is struck upwards, as if to throw it up 

 in the air, the glasses will break if the blow be 

 strong, and if the blow is not very "quick, the 

 water will be spilt without breaking the glasses. 



When the performer supports a man upon his 

 belly as in Fig. 55, he does it by means of the 

 strong arch formed by his backbone, and the 

 bones of his legs and thighs. If there were 

 room for them, he could bear three or four, or, in 

 their stead, a great stone to be broken with one 

 blow. 



A number of feats of real and extraordinary 

 strength were exhibited, about a century ago, in 

 London, by Thomas Topham, who was five feet 

 ten inches high, and about thirty-one years of 



