28 FRAGMENTS OF SCIENCE 



of science apply the unintelligent impulse with which Mr. 

 Mozley credits them, and which shall show, by illustra- 

 tion, the surreptitious method whereby they climb from 

 the region of facts to that of laws. 



Before the sixteenth century it was known that water rises 

 in a pump ; the effect being then explained by the maxim 

 that " Nature abhors a vacuum." It was not known that 

 there was any limit to the height to which the water would 

 ascend, until, on one occasion, the gardeners of Florence, 

 while attempting to raise water to a very great elevation, 

 found that the column ceased at a height of thirty-two 

 feet. Beyond this all the skill of the pump-maker could 

 not get it to rise. The fact was brought to the notice of 

 Galileo, and he, soured by a world which had not treated 

 his science over-kindly, is said to have twitted the philos- 

 ophy of the time by remarking that Nature evidently 

 abhorred a vacuum only to a height of thirty-two feet. 

 Galileo, however, did not solve the problem. It was taken 

 up by his pupil Torricelli, to whom, after due pondering, 

 the thought occurred, that the water might be forced into 

 the tube by a pressure applied to the surface of the liquid 

 outside. But where, under the actual circumstances, was 

 such a pressure to be found? After much reflection, it 

 flashed upon Torricelli that the atmosphere might pos- 

 sibly exert this pressure; that the impalpable air might 

 possess weight, and that a column of water thirty-two feet 

 high might be of the exact weight necessary to nold the 

 pressure of the atmosphere in equilibrium. 



There is much in this process of pondering and its 

 results which it is impossible to analyze. It is by a kind 

 of inspiration that we rise from the wise and sedulous 

 contemplation of facts to the principles on which they 



