190 LABORATORY LESSONS IN GENERAL SCIENCE 



pendulums; (6) of the square roots of the two pendulum 

 lengths. [Use smaller number for divisor in both cases.] 



3. Make the pendulum length 39 + inches, and count the 

 oscillations per minute. 



4. With a stronger force pulling the 

 pendulum down, what would probably be 

 true (a) of the rate of motion of the pendu- 

 lum ; (b) of the number of oscillations per 

 minute? Since the force of gravity varies 

 in different latitudes, what must be true of 

 the lengths of pendulums to make the same 

 number of oscillations per minute in differ- 

 ent localities? What must be true of the 

 lengths of second's pendulums in different 

 places ? 



5. Recall the effect of temperature 

 changes (heat and cold) upon lengths of 

 bodies. What must be true of the pendu- 



\J lum length in the same clock (a) summer 



and winter; (6) through a day? What 

 FIG. 84. A clock effect has this on the time for one oscillation 

 escapement. of Q^ pen( j u l um ? What means are em- 

 ployed to secure uniform oscillation periods for the same 

 pendulum ? 



6. Secure an old clock from which the dial has been 

 removed. Find the number of oscillations that allow one 

 tooth of the wheel to pass the escapement. Count the teeth 

 of this wheel. Calculate the number of oscillations for every 



