GALILEO AND THE NEW PHYSICS 



curious facts were soon ascertained. Galileo found, 

 for example, that a pendulum of a given length per- 

 forms its oscillations with the same frequency though 

 the arc described by the pendulum be varied greatly. 1 

 He found, also, that the rate of oscillation for pen- 

 dulums of different lengths varies according to a simple 

 law. In order that one pendulum shall oscillate one- 

 half as fast as another, the length of the pendulums 

 must be as four to one. Similarly, by lengthening the 

 pendulums nine times, the oscillation is reduced to 

 one-third. In other words, the rate of oscillation of 

 pendulums varies inversely as the square of their 

 length. Here, then, is a simple relation between the 

 motions of swinging bodies which suggests the relation 

 which Kepler had discovered between the relative 

 motions of the planets. Every such discovery coming 

 in this age of the rejuvenation of experimental science 

 had a peculiar force in teaching men the all-important 

 lesson that simple laws lie back of most of the diverse 

 phenomena of nature, if only these laws can be dis- 

 covered. 



Galileo further observed that his pendulum might 

 be constructed of any weight sufficiently heavy read- 

 ily to overcome the atmospheric resistance, and that, 

 with this qualification, neither the weight nor the ma- 

 terial had any influence upon the time of oscillation, 

 this being solely determined by the length of the cord. 

 Naturally, the practical utility of these discoveries 

 was not overlooked by Galileo. Since a pendulum 

 of a given length oscillates with unvarying rapidity, 

 here is an obvious means of measuring time. Galileo, 

 however, appears not to have met with any great 



VOL. ii. 8 IOI 



