But there is no well-authenticated instance of those prodigious shoals of herrings having been met with approaching the south in any high northern latitude; and so far from their abounding in the Arctic regions, none have been found in the Greenland seas, nor have any been discovered in the stomachs of the whales killed there. Egede, who resided in Greenland for fifteen years, and compiled the natural history of it, after enumerating the fishes, adds, “No herrings are to be seen;” whilst on the contrary, the whales which feed principally on herrings, frequent our own coasts. These arguments appear to be fatal to the theory of the Arctic migration, and to support most powerfully that of the mere retirement of the herring to the deep. But Mr Mitchell goes farther, and asserts, upon the evidence of the celebrated naturalists Bloch and Lacepede, that “fishes of a similar size even in fresh water cannot go above half a mile a-day, and that therefore herrings could not make, even from spring to autumn, the long voyage attributed to them.” Now, this appears to be going too far, and we would prefer that the argument should rest on the former grounds, excluding this, which seems to be a weak assertion, founded upon the observation that fishes do not proceed far from their haunts, whilst the fact is, that they merely move about in search of food; but who that has seen the rapid movement of a trout, or of the very fish we are treating of, could for a moment entertain the idea of their progress being confined to a rate that the crawling snail might equal? Mr Mitchell himself mentions a fact that alone is sufficient to rebut such an assertion, namely, that shortly after the union between England and Scotland, an immense shoal of herrings ran ashore near Cromarty, and covered the beach to the depth of several feet; and he adds, “Strange to say, however, the shoal left the Frith in a single night, and no shoals made their appearance again for more than half a century.” Now, if they could make but half a mile a-day, how could they have returned several miles in a single night? But this argument was unnecessary, and it would be well for many persons to know that an ill-sustained argument is not merely a bad prop to a cause, but a wedge inserted for the advantage of an adversary, placed ready for his use in overturning it.