duty to supply the one and to correct the other; and consider that an acknowledgment of the latter is the greatest mark of respect I can pay to that body under whose protection they were laid before the readers of its Transactions.
No apology can be offered for want of industry; but the extent of this island, the difficulty of traversing it, and the intricate disposition of its rocks, offer some excuse for deficiencies, where want of time was further superadded to all other obstacles. For errors there is no excuse, but in correcting them it will not be useless to point out the causes from which they arose, since other observers may take warning from them, and learn to mistrust all observations which are not founded on rigid investigation, free from conjecture, and free from system.
To conclude respecting what is, from that which ought to be, will lead, as it has already led, to greater errors than those which I shall have to record. Equal hazard arises from judging of the structure of a district by the examination of specimens only. In rocks the specimen is not always an abstract of the geological nature of the series in which it occurs, and the mistakes which have here arisen from this cause will be equally apparent with those which have resulted from the preceding one. The last source of error which I shall notice was the imperfection of the outline of the island as it is given in Mackenzies chart by which I was guided. Here, among other similar errors, the distance between the head of Loch in daal and that of Loch Eishort, which scarcely exceeds a mile and a half, is marked at five miles. Hence, finding my observations to disagree with the map on which I attempted to record them, I abandoned altogether a pursuit which, had I continued it, would have led me at that time, as it has since done, to determine the sandstone series to a much greater extent than I then imagined it to occupy.
