And it is after this manner that one may break a whip cord, nay, a small jack-line with one's hand without hurting it; only by bringing one part of the rope to cut the other; that is, placing it so round one's left hand, that by a sudden jerk, the whole force exerted shall act on one point of the rope.
B is a feather bed upon which the performer falls.
The posture of Fig.

4 Plate 19 (where the strong man having an anvil on his breast or belly, suffers another man to strike with a sledge hammer and forge a piece of iron, or cut a bar cold with chizzels) tho' it seems surprising to some people, has nothing in it to be really wondered at; for sustaining the anvil is the whole matter, and the heavier the anvil is, the less the blows are felt: And if the anvil was but two or three times heavier than the hammer, the strong man would be killed by a few blows; for the more matter the anvil has, the more INERTIA and the less liable it is to be struck out of its place; because when it has by the blow receiv'd the whole MOMENTUM of the hammer, its velocity will be so much less than that of the hammer as it has more matter than the hammer.

Neither are we to attribute to the anvil a velocity less than the hammer in a reciprocal proportion of their masses or quantities of matter; for that would happen only if the anvil was to hang freely in the air (for example) by a rope, and it was struck horizontally by the hammer.

Thus is the velocity given by the hammer distributed to all parts of a great stone, when it is laid on a man's breast to be broken; but when the blow is given, the man feels less of the weight of the stone than he did before, because in the reaction of the stone, all the parts of it round about the hammer rise towards the blow; and if the tenacity of the parts of the stone, is not stronger than the force with which it moves towards the hammer, the stone must break; which it does when the blow is strong, and struck upon the centre of gravity of the stone.
In the 6th Fig.

of Plate 19, the man IHL (the chairs IL, being made fast) makes so strong an arch with his backbone and the bones of his legs and thighs, as to be able not only to sustain one man, but three or four, if they had room to stand; or, in their stead, a great stone to be broken with one blow.
In the 6th and 7th Fig.