We can easily fix a circumscribed geographical boundary to any species of Mammalia. They may be limited to a country, or even a district. Can we impose a like distribution on birds? At first sight this seems difficult: their powerful organs of locomotion permit of their travelling rapidly; and, moreover, their nature, essentially mobile, and their wandering humour, lead them to continual change; and then their organisation adapts them for great extremes of temperature--circumstances which would lead us to consider them quite cosmopolite. Nevertheless, many species reside habitually in countries of very limited range. A Sovereign Hand has traced on the surface of the globe limits that cannot be passed. How such small creatures are able to perform such distant journeys, pausing only at far-severed resting-places for necessaries, has always been a matter of surprise. They pass on without an instant's sleep, however long and fatiguing the route. How can the Quail, for instance, with its short wing and plump body, traverse the Mediterranean twice in the year? Hasselquist tells us that small short-winged birds frequently came on board his ship in squally weather, all the way from the Channel to the Levant; and Prince Charles Bonaparte was agreeably surprised by the visit of a party of Swallows to the ship _Delaware_, in which he was a passenger, when five hundred miles from the coast of Portugal, and four hundred from Africa. Audubon relates a similar occurrence; and numerous instances are recorded in which these fatigued travellers have taken shelter in the first fisherman's boat they met, sometimes so weak as to be hardly able to move a wing. It is therefore a fact truly inexplicable, in spite of every hypothesis, more or less reasonable, which has been advanced by naturalists in explanation. Men have little influence over birds, and have, therefore, few opportunities of studying their habits in a state of nature. Some few species may be retained in captivity, and some observers have been able to obtain their entire confidence while in that condition; but, except two or three species, it has not been possible to reduce them to a state of domestication. Our knowledge of the habits and manners of the feathered race is, therefore, entirely dependent on chance observation. The Humming-bird is confined to certain portions of America. The Nightingale, if a visitor to Scotland, is only found in Berwick and Dumfriesshire in fine seasons, while it is constantly seen in Sweden, a country much colder and much more northerly. The Toucans, so brilliant in plumage, are only found in tropical South America. The Swallow, so rapid on the wing, clearing its twenty leagues an hour when it leaves us for its southern winter quarters, never deviates from the route which seems to have been traced for it by a Sovereign Master.