TABLE ITI. 



From these values, the probable errors of the observed times of swing of the different 



pendulums are calculated in the usual way. 



/v t^^\ 

 ~ ^ '. where n = number 



nl 



of observations. 

 Probable error of a single observation by No. 5 e a - 3-7 X 10~ 7 sees. 



JJ )l ' fy 



) ) ) ! I ! -^ A ^21 : = ^ ' ' 



,, ,, mean pendulum e m : = 1 -9xlO~ 7 sees. 



Probable error of the mean result for any pendulum, 



. . (I) 



Therefore, the probable error of mean result given by No. 5 = p ; , 



j> >j i) 7^7 



l-2xlO- 7 secs. 

 1-5 



,, , ,, ,, mean pendulum == p,, t = 0-6 X I0~ 7 sees. 



Considering paired observations alone (column B), we get 



TABLE IV. 



15 



