No. 7 



No. 21 



Rise of Temperature 

 per hour. 

 1-18C. 

 -49 

 -64 

 -28 



.. 0-59C. 

 -66 

 -47 

 -42 



Correction applied. 



+30x10- 



+ 12 

 + 16 

 + 7 

 + 15 

 + 16 

 + 12 

 + 10 



sec. 



PROBABLE ERRORS OF THE FINAL RESULTS. 



In discussing the results of the observations, calculations have been made in each 

 case which give criteria for the accuracy of these observations. These criteria do not 

 show, however, the possible error of the observations, and are chiefly of service in esti- 

 mating the degree of reliability which can be placed on the final arithmetical means. 



The Table below gives the values obtained : 



TABLE LXVII. 



Here, e^ is the probable error in the time of swing of the pendulum x, swung once. 



e, n is the probable error in the time of one swing of the mean pendulum.* 



e m is the mean value of the probable errors calculated from the differences between 

 the mean and each pendulum, while p m is the probable error of the mean value of 

 all swings of the mean pendulum. 



It will be clear that the method of derivation of these figures allows a comparison 

 to be made which enables one to obtain some insight into the causes of the errors 

 observed. The most important errors to which the observations at field stations were 



* The time of swing of the mean pendulum is the mean of the times of swing of the three 

 pendulums numbered 5, 7 and 21. 



