30 SCIENCE OF COMMON THINGS. 



Length of pendulum affects the rate of a clock. 



Because the pendulum-rod becomes contracted by 

 cold in winter, and lengthened by heat in summer. 



174: Why does a change in the length of the pendulum cause a clock to 

 go faster or slower f 



The number of vibrations which a pendulum makes 

 in a giyen time depends upon its length, because a 

 long pendulum does not perform its journey to and 

 from the corresponding points of its arc so soon as a 

 short one. 



