II III] Introduction xix 



Therefore by formula (i) p. xiii : 



KQ v -4,9 



*, = -398,6233 - -58 [1793] + -^-^ [397] 



= -398,6233] 



-1040> = -398,5241. 

 + 48j 



Or, we might proceed as follows: for the Poll-men ^(1 a) = -4817, hence 

 a = -0366. But from Table III, p. 9, which gives z for a: 



a = -03, z = -398,6603 

 a = -04, z = -398,4408 

 = -66,' A,= -2194 



A 2 = -627. 

 Hence by formula (i): 



fifi x -^4, 

 *, = -398,6603 - -66 [2194] + - - [627] 



z 



= -398,0603] 



-1448> =-398,5225. 



+ 70J 



We conclude therefore that z would be correct to five figures with second differ- 

 ences, and that for four figures, first differences from either Table II or Table III 

 will suffice. 



If we use formula (ii) p. xiii Everitt's formula we find from Table II : 



*, = -398,6233 - -58 [1793] + " '" [397] + 



= -398,6233 v 



- 1 040 1 



+ M . -398,52!,, 



+ 5 

 and from Table III : 



z, = -398,6603 --C6 [2194]+'' -[627] + '^^ ^*[ 6 27] 



= 398,6603; 



-1448 



J- = -398,5223. 



+ 31 ) 



Working with formula (iii), Table II gives us ^='398,5242 and Table III 

 z t = "398,5225 with second differences. We shall not therefore without higher 

 differences get from any of our formulae closer than '398,522 with a possible error 



9 



