GRAVITATION. 39 



able man had talent enough for seeing how matters 

 stood, but he had too much timidity for speaking it 

 boldly. " Nature did abhor a void, but her abhor- 

 rence extended only to thirty-two feet." Torricelli, 

 equally gifted and more daring, took a glass tube four 

 feet long, sealed it hermetically at one end, filled it 

 with mercury, placed his finger on the end, inverted it 

 in a basin of mercury, and down sunk the column in 

 the tube to the height of about thirty inches above the 

 surface of that in the basin. Here was nature's ab- 

 horrence lessened in the case of mercury to about one 

 twelfth of what it had proved to be in the case of 

 water ; and that was nearly inversely as their specific 

 gravities ; or the thirty-two feet of water and the thirty 

 inches of mercury, were, upon equal bases, nearly of 

 the same weight. Thus Nature's abhorrence was, in fact, 

 reduced to that of a smaller weight in the same cir- 

 cumstances weighing down a greater : in other words, 

 an abhorrence of the less being the greater and the 

 greater the less, a very natural abhorrence for the 

 good old lady. Torricelli filled up his basin with 

 water, raised the tube so that the open or lower end of 

 it was above the mercury, but v not above the water ; 

 out ran the mercury ; and the water entered, and 

 filled the tube to the top. Thus the atmosphere was 

 weighed, and the barometer invented, not only to tell 

 the weight of the whole, but of any fraction of the 

 height, and to indicate the changes. If this was done, 

 and done with such apparent ease, that it almost did 

 itself, we are not entitled dogmatically to maintain 

 that the beams of light themselves shall not yet be 

 weighed, or that the influence of the sun shall not be 



