errors of those who have preceded me, I have rarely if ever attempted to draw such general conclusions. My chief endeavour has been to reduce questions of this nature to a narrow compass, where the limits admitted of contraction; and where any thing has appeared uncertain or contradictory, to put those uncertainties and contradictions in the clearest light, that future observers might direct their attention to those points which most stand in need of elucidation.
To place the subjects which have occurred in the examination of Sky, in an order as nearly as possible both conducive to topographical clearness and geological elucidation, I have varied the order of description as circumstances dictated. When the structure was simple, and the geographical details corresponded, the task has been easy to the writer, and will be easy to the reader. When it has been otherwise, I have attempted as far as possible to reconcile these claims; while in the greater number of instances, where the intricacy of the geological structure and the scattered disposition of the materials over a large extent of surface have prevented all possibility of reconciliation, I have been obliged in some measure to divide the subject with a reference to both these objects, preferring to incur the charge of prolixity rather than that of obscurity. I shall therefore commence by giving a general sketch of the several rocks which form the island, noting their geographical positions as accurately as circumstances permit; after which I shall attempt to trace their geological arrangement, entering more largely on those details which lead either to useful doubts or probable elucidation.
The want of accurate geodesic operations has left the form, dimensions, and position of Sky, as yet desiderata in British geography, an inconvenience however, much less in a geological view
