372 NATURE AND MAN. 



which suggested to him a series of experiments upon the vibrations 

 of pendulums of different lengths— without, however, causing him 

 to pursue the subject further than the devising an instrument for 

 measuring the rate of the pulse. But the interest he took in the 

 study of mathematics and mechanics proved so strong as to lead 

 him to devote himself entirely to them, with a success that caused 

 him to be appointed lecturer on those subjects at the University. 

 Although no religious reformation could then make head in Italy, 

 a revolt against the domination of Aristotle was beginning to 

 break out among its scientific men ; and undeterred by the fate 

 of Giordano Bruno (who was burnt by the Inquisition at Rome in 

 1600), Galileo early joined the movement party. One of the first 

 of the Aristotelian doctrines which he called in question, was that 

 which I have just cited. He saw that it must be erroneous, as 

 taking no account of the very obvious consideration that while 

 the "pull" of the earth on the weight of 10 lbs. is ten times as great 

 as it is upon the weight of i lb., it has to give motion to ten times 

 the mass ; so that the rates of fall of the two bodies would be the 

 same. His teaching on this subject being opposed by his col- 

 leagues, Galileo, in the presence of the whole University, ascended 

 the " leaning tower," and dropping from its summit bodies of 

 different weights, he showed that (with an inconsiderable differ- 

 ence, due to the resistance of the air) they reached the bottom in 

 the same times. 



As the monument of an experiment which gave the death-blow 

 to the tmscietitific legislation of Aristotle, and prepared the way for 

 the scientific legislation of Newton, the " leaning tower " of Pisa 

 beautiful in itself as an architectural work, has a far grander in- 

 terest for all who can appreciate this great step in the emancipation 

 of thought, which should cause it to be preserved with the most 

 jealous care so long as its stones will hold together. 



But this demolition of an old error was only the first result of 

 Galileo's experimental researches. For he found, by letting fall 

 similar weights from different heights, that the rate of motion of 

 the falling body continually increases as it descends ; a body that 

 falls 16 feet in one second, falling 64 feet in two seconds, 144 feet 

 in three seconds, and 256 feet vafour seconds, this last being prob- 

 ably the greatest height at which he could experiment These 



