158 Dr. Mac Culloch's Supplement to the 



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 dis- 

 position 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 con- 

 tinued 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. \ 



