and amplitude are observed before and after the observations proper, and their appro- 

 priate corrections applied in order to reduce to normal temperature and pressure. 

 The three pendulums are swung in turn in this way. Kach set of observations takes 

 about 40 minutes and the whole series about 2-J- hours. 

 A specimen page from the note-books is given below. 



Mean Time, 11 h. 10 in. Date, March 2nd, 1913, a.m. Observer, C. S. W. 

 Mean Barometer, 29-91 inches. Pendulum Number, 5. 



hr. min. sec. 



3 20 



21 



23 



24 



25 



26 



28 



29 



24-7 

 53-7 

 23-4 

 52-5 

 22-4 

 51-3 

 21-2 

 50-0 

 20-0 

 48-9 

 18-8 

 47-7 

 17-6 

 46-5 

 16-5 

 44-4 

 15-4 

 ll-:; 

 14-1 

 43-2 



mm. sec. 

 Difference=29 24-1 



mm. sec. 



It is clear that the observation of " time of swing " of the pendulums in any location 

 does not give a value for gravity. Only when the length / of the pendulum is invariable 



A 4 



