how a better value can be derived. The uncertainty should not, however, be more 

 than tliis in the case of a station such as Melbourne. 



(7) Probable error of the Potsdam observations. 



Including the error due to variability of the pendulums, the probable error of 

 the value of the Potsdam mean works out to less than 2-OxlO~ 7 sec., which we will 

 therefore take as the maximum value. 



The final probable error of the determination of the time of swing at the field 

 stations we will denote by K, 



where K == /(!)+ ( 2 )'+ (3)'+ + - - 



For convenience, these values are put down in Table LXXI, in units of the 7th 

 decimal place of a second. 



TABLE LXXI.* 



(UtlOUlU. 



This amounts to an addition of 3xlO~ 7 sec. to the observed time of swing. 



1 The figures for Christcliurch have not been evaluated in view of the discordant results by the 

 dilTi-rcut pendulums. 



| The Hcamen used to declare that the setting up of the transit instrument was an unfailing sign of 

 approaching blizzards as, indeed, it usually was. 



90 



