XXXIII. Note on Archdeacon Pratt's paper 'on the effect of local attraction in the English arc.'

The distances between the parallels of latitude of the principal stations of the original English Arc, as used by Archdeacon Pratt in his paper “On the Effects of Local Attrac­tion*,” are taken from the second and third volumes of the “Account of the Trigono­ metrical Survey.” The correct distances, with the exception of that for Blenheim, are given at page 732 of the last published volume of the Ordnance Survey. They are as follows:- Fect Dunnose and Greenwich ........ 313716.9 Greenwich and Blenheim ........ 132802.0 Blenheim and Arbury Hill ......... 139837.4 Arbury Hill and Clifton ......... 450225.2 Clifton and Burleigh Moor ........ 406596.9 The distance, Greenwich to Bleinheim, is not altered, as there is no new determina­tion of that quantity. The quantities λ and μ, as used by Archdeacon Pratt, do not require alteration.