MIRACLES AND SPECIAL PROVIDENCES 



107 



that which generalises the commonest 

 observation of nature." 



The eloquent pleader of the cause of 

 miracles passes over without a word the 

 results of scientific investigation, as 

 proving anything rational regarding the 

 principles or method by which such 

 results have been achieved. Here, as 

 elsewhere, he declines the test : "By 

 their fruits shall ye know them." Perhaps 

 our best way of proceeding will be to 

 give one or two examples of the mode in 

 which .men of science apply the unintel- 

 ligent impulse with which Mr. Mozley 

 credits them, and which shall show, by 

 illustration, 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 occa- 

 sion, 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 philosophy 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 possibly 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 hold the 



pressure of the atmosphere in equili- 

 brium. 



There is much in this process of 

 pondering and its results which it is 

 impossible to analyse. It is by a kind 

 of inspiration that we rise from the wise 

 and sedulous contemplation of facts to 

 the principles on which they depend. 

 The mind is, as it were, a photographic 

 plate, which is gradually cleansed by the 

 effort to think rightly, and which, when 

 so cleansed, and not before, receives 

 impressions from the light of truth. 

 This passage from facts to principles is 

 called induction ; and induction, in its 

 highest form, is, as I have just stated, a^ 

 kind of inspiration. But, to make it 

 sure, the inward sight must be shown to 

 be in accordance with outward fact. To 

 prove or disprove the induction, we must 

 resort to deduction and experiment. 



Torricelli reasoned thus : If a column 

 of water thirty-two feet high holds the 

 pressure of the atmosphere in equili- 

 brium, a shorter column of a heavier 

 liquid ought to do the same. Now, 

 mercury is thirteen times heavier than- 

 water ; hence, if my induction be correct, 

 the atmosphere ought to be able to sus- 

 tain only thirty inches of mercury. Here, 

 then, is a deduction which can be imme- 

 diately submitted to experiment. Torri- 

 celli took a glass tube a yard or so in 

 length, closed at one end and open at 

 the other, and, filling it with mercury, he 

 stopped the open end with his thumb, 

 and inverted it into a basin filled with 

 the liquid metal. One can imagine the 

 feeling with which Torricelli removed his 

 thumb, and the delight he experienced 

 on finding that his thought had forestalled 

 a fact never before revealed to human 

 eyes. The column sank, but it ceased 

 to sink at a height of thirty inches, leav- 

 ing the Torricellian vacuum over head. 

 From that hour the theory of the pump 

 was established. 



The celebrated Pascal followed Tor- 

 ricelli with another deduction. Pie 

 reasoned thus : If the mercurial column 

 be supported by the atmosphere, the 

 higher we ascend in the air, the lower 



