SURVEY OF THE BRITISH ISLES FOR THE EPOCH JANUARY 1, I88G. 
277 
which is the most easterly point on the island, the longer axis of the mass runs north 
and south. Its height on the inland side is from 20 to 40 feet, while it falls steeply 
towards the sea. On another hill which rises behind Kaill, the residence of R. Thom, 
Esq., the columnar mass is small and more clearly defined. The north or landward 
side is 15 or 20 feet higli, the south side is a steep cliff We roughly estimate the 
length at about 50 yards. In fig. 13 the position of this hill is indicated by B, that 
of the highest point on the island by A, and that of Compass Hill by C. 
In 1884 we determined the magnetic elements by means of the Kew Magnetometer 
No. 60, and the Dip Circle No. 74, at the position marked P. The differences between 
the observed and calculated values are given in the following table :— 
Date 1884. 
Decimation. 
Dip .... . . 
Horizontal Force 
Observed. 
Calculated. 
Difference. 
21 s'a 
72 45-0 
1-5092 
2°3 6-5 
71 32-7 
1-5607 
o / 
-1 58-1 
1 12-3 
— -0515 
Stations on Caiina. 
Although these observations show that the station was highly disturbed, the effect 
on the Declination is not so great as to be detected, except by a careful observation. 
In 1888 we observed by means of a small azimuth compass at 23 stations which are 
indicated on the map, and determined at each the bearings of a number of distant 
points. The observations were made on August 16 and 17, bright sunny days with 
a northerly wind, on which the atmosphere was very transparent. We were therefore 
able to take the bearings, not only of prominent headlands on Skye and Bum, but also 
of some distant objects, such as the Ushinish Lighthouse on N. Uist in the Hebrides. 
The azimuth compass was a small instrument which did not admit of great accuracy, 
but, as will be seen in the sequel, it v^as suflicient for the purpose we had in view. 
