SURVEY OF THE BRITISH ISLES FOR THE EPOCH JANUARY 1, 1886. 
89 
These results indicate—(1) that the secular change is greater in the northern than 
in the southern parts of the United Kingdom; (2) that it was much larger between 
the years 1857-86 than during the interval 1837-57 ; and, lastly, (3) that, in the 
north at all events, the rate of annual decrease is ao’ain diminishing:. 
The first of these conclusions difiers from that arrived at by Sir E. Sabine when 
collating the 1837 and 1857 surveys. He assumed (‘Phil. Trans.,’ vol. 160, 1870, 
p. 268) “an annual decrease of West Declination of approximately 5’'6 in Scotland 
and the north of England, increasing to 6'‘2 in the middle und southern parts of 
England and to 6' in Ireland.” 
Our conclusion that, at the present time, the rate is greater in the north is borne 
out by the values deduced by M. Moureaux from his own observations and the maps 
of Lamont {loc. cit., p. 162). The values he gives for stations on the Mediterranean 
and on the English Channel are about —6'’5 and — 7''7 respectively, which indicates 
an increase of about 0'‘2 on the rate for each degree of latitude as we go north. 
The truth of the second conclusion is rendered more apparent by calculating the 
annual rate for the epoch 1837-57 instead of 1857-86, as shown in the following 
Table for the Scotch stations, for which the rec[uisite data are available ;—• 
Mean Annual Decrease of Declination. 
Station. 
1837 to 1857. 
1857 to 1886. 
Station. 
1837 to 1857. 
1857 to 1886. 
Lerwick 
— 5'5 
- id-o 
Inverness . 
- 6-3 
- 9-0 
Kirkwall . . . 
- 4-.5 
- 10-5 
Abei'deen '. 
- 6-8 
- 8-9 
Wick .... 
- 4-8 
- lO-o 
Loch Inver 
- 2-9 (?) 
- 11-8 
Golspie .... 
- 5-0 
- 10-4 
The third conclusion is supported by a comparison of M. Moureaux’s rates for the 
epoch 1859-1885 with those obtained by collating as before his results and those of 
the Kev. S. J. Perry {he. cit.). 
MDCCCXC.—A. 
N 
