SURVEY OF THE BRITISH ISLES FOR THE EPOCH JANUARY 1, 1886. 295 
these, Lerwick, we disregard, as it lies so far from the rest of the district. In five 
out of the remaining six the disturbance of the middle epoch as deduced from the 
isogonals given by Sir F. Evans is intermediate to those which were obtained in 1857 
and 1886. At Oban there is an enormous discrepancy, which is not supported by 
Directions of Declination Disturbances. 
the observations made in 1872 and by ourselves on the neighbouring island of 
Kerrera. There can be little doubt that the 1872 observation was subject to a 
powerful local disturbance. The coincidence of the results in the other cases can 
hardly be accidental. The figures are given in the following Table, Kerrera being 
added for the sake of comparison with Oban 
