Page:A Journey to the Western Islands of Scotland - Johnson (1775).djvu/354

 vel unprovided with instruments for taking heights and distances.

There is yet another cause of errour not always easily surmounted, though more dangerous to the veracity of itinerary narratives, than imperfect mensuration. An observer deeply impressed by any remarkable spectacle, does not suppose, that the traces will soon vanish from his mind, and having commonly no great convenience for writing, defers the description to a time of more leisure, and better accommodation.

He who has not made the experiment, or who is not accustomed to require rigorous accuracy from himself, will scarcely believe how much a few hours take from certainty of knowledge, and distinctness of imagery; how the succession of objects will be broken, how separate parts will be confused, and how many particular features