AILSA. GENERAL DESCRIPTION. 491 



to comprehend the variety and distribution of its parts, 

 and to distinguish that intricacy of local colouring for 

 which a certain degree of proximity is always required. It 

 is partly owing to the beauty of the local colour, the 

 mild tones of grey interspersed with greens of every 

 tint, that the columnar ranges of Ailsa produce an effect 

 so far superior to those of Staffa, of the Shiant isles, 

 or of Sky ; the uniform dark hue of these, without 

 variety or contrast, often confounding the whole in 

 indiscriminate gloom. 



This island is situated in the firth of Clyde at nearly an 

 equal distance from the shores of Ayr and Argyll, ap- 

 pearing like the summit of a vast mountain rising abruptly 

 out of the deep. When viewed from the east or west, 

 it has the figure of a right angled cone, while from 

 the north or south it presents one considerably obtuse. 

 This difference is the result of its form, which is that 

 of a conoidal body with an irregularly elliptical basis. 

 The altitude, as ascertained by trigonometrical measure- 

 ment from a mean of numerous observations, is 1100 

 feet. The lateral dimensions cannot be computed by 

 any ordinary means, as it is impossible either to traverse 

 the ground or to make the circuit of the hill ; but they 

 may be estimated to a sufficient accuracy for general 

 purposes, by comparing the lengths of its base with 

 the measured altitude, from such a distance as to prevent 

 any error from too low a position of the eye. This 

 estimate gives its length about 3300 feet and its breadth 

 2200 or thereabout. The shore around is clean, and 

 the water at a small distance so deep that ships may 

 range it with safety ; while, on the east side, a convenient 

 landing place for boats is afforded by a spit of rolled 

 pebbles that has been washed up by the alternate opposing 

 run of the tide stream. This is the only point at which 

 the rock can be ascended from the shore; the other 

 sides being either perpendicular, or presenting rugged 

 and unsurmountable acclivities. These, at the north side, 



