Why is the eagle and some other birds enabled to bear the strongest light of the sun?

Because it has a membrane (see page 8,) with which the bird can, at will, cover the pupil of the eye, while the eyelids remain open.

Why are aqueous birds better supplied with food than those on land?

Because fish, the food of the former, are probably but little influenced by season; while our poor land birds find theirs to be nearly annihilated in some

cases.

Why is the plumage of aquatic birds kept dry?

Because the small feathers next the bird fall over each other like the tiles of a roof, and thus throw off the water.

Paley tells us that the lamina or layers of the feathers of birds are kept together by teeth that hook into each other, "as a latch enters into the catch, and fastens a door."""

Why have birds two united glands on the rump?

Because these glands secrete a mucous oil, which can be pressed out by the bill of the bird, to anoint its feathers, and replace them when they are discomposed. Aquatic birds have their feathers dressed with this oil from first leaving the shell, but the feathers of other birds are pervious to every showThomson thus alludes to this oleous unction:

er.

'The plumy people streak their wings with oil,
To throw the lucid moisture off.'

Why have birds the pip?

Because the oleous glands just described, become diseased and swollen. It is generally remedied by a single puncture, by which the collected fluid may be discharged. Jennings' Ornithologia.

Why do dab-chicks, moor-hens, and coots, fly erect, with their legs hanging down, and hardly make any despatch?

Because their wings are placed too forward out

of the true centre of gravity; as the legs of auks and divers are situated too backward. G. White. Why do penguins, and birds of the same group walk nearly upright?

Because the legs are placed farther back than in other birds.

Why is the ancient custom of giving parish rewards for the destruction of small birds as vermin, still continued?

Because it may have been requisite in foriner times, to keep under or reduce the numbers of many predaceous animals, which, in a thickly wooded country, with an inferior population, might have been productive of injury; and we even find parliamentary statutes enacted for this purpose: but now, however, our loss by such means has become a very petty grievance; our gamekeepers do their part in removing pests of this nature, and the plough and the axe leave but little harbour for the few that escape; and thus we war on the smaller creatures of creation, and call them vermin. An item passed in one of our churchwardens' accounts, was, 'for seventeen dozen of tomtits' heads! In what evil hour, or for what crime, this poor little bird can have incurred the anathema of a parish, it is difficult to conjecture. The price set upon its head is four-pence per dozen, probably the ancient payment when the groat was a coin. - Knapp.

MIGRATION.

Why has the existence of migration been denied? Because of the surprise, how migrating birds could support themselves so long on wing, as to accomplish their journeys, and at the same time live without food during their voyage. These difficulties, however, vanish altogether if we attend to the rapidity of the flight of birds. Hawks and many other birds probably fly at the rate of 150 miles an

hour: an eider-duck at 90 miles an hour: Sir George Cayley computes the common crow to fly at nearly 25 miles an hour; and Spallanzani found that of the swallow about 92 miles, while he conjectures the rapidity of the swift to be nearly three times greater. A falcon which belonged to Henry IV of France, escaped from Fontainbleau, and in twenty-four hours afterwards was found at Malta, a distance computed to be no less than 1530 miles ; a velocity nearly equal to 57 miles an hour, supposing the falcon to have been unceasingly on the wing. But, as such birds never fly by night, and allowing the day to be at the longest, his flight was perhaps equal to 75 miles an hour. If we even restrict the migratory flight of birds to 50 miles an hour, how easily can they perform their most extensive migrations! Fair winds may perhaps aid them at the rate of 30 or 40 miles an hour; nay with three times greater rapidity. Fleming.

The migrations of the feathered tribes have been the object of popular observation, since the days of the prophet Jeremiah: For the stork in the heaven knoweth her appointed times; and the turtle and the crane, and the swallow, observe the time of their coming.' (ch. viii, v. 7.)

Why are certain migrating birds called Summer Birds of Passage?

Because they arrive in this country in the spring, and depart from it in the winter.

Why are other migrating birds called Winter Birds of Passage?

Because they arrive in autumn, and depart in spring..

Why may the autumnal shifting of birds, with propriety, be termed their Equatorial Migration?

Because all those species in which it is observed, move from the Pole towards the Equator, in search of the temperature congenial to their constitutions, and

which the winter of the district of their summer residence could not afford. -- Fleming.

Why may the vernal shifting, with equal propriety be termed the Polar Migration?

Because all the species recede with the increasing temperature of the high latitudes of the Equator, and approach towards the Pole. - Fleming.

Why do certain birds migrate to mild countries on the approach of winter?

Because they are unable sufficiently to provide against the vicissitudes of the seasons, by varying the quantity and colour of their dress; but are thus protected by shifting their quarters, so as to live throughout the whole year in a temperature congenial to their constitutions. Fleming.

Why are birds sometimes found at sea, in a very exhausted state, on the rigging of ships?

Because, in their annual migrations, birds are occasionally overtaken by storms of contrary wind, and carried far from their usual course.

Mr White, however, in his Natural History of Selborne, says, 'It does not appear to me that much stress may be laid on the difficulty and hazard that birds must run in their migrations, by reason of vast oceans, cross-winds, &c; because, if we reflect, a bird may travel from England to the Equator without launching out or exposing itself to boundless seas and that by crossing the water at Dover, and again at Gibraltar. And I with the more confidence. advance this obvious remark, because my brother has always found that some of his birds, particularly the swallow kind, are very sparing of their pains in crossing the Mediterranean; for, when arrived at Gibraltar, they do not

Flying, and over lands with mutual wing
Easing their flight;-

Milton.

but scout and hurry along in little detached parties of six or seven in a company; and sweeping low, just over the surface of the land and water, direct their course to the opposite continent, at the narrowest passage they can find. They usually slope across the bay to the south west, and so pass over opposite to Tangier, which, it seems, is the narrowest space.'

Why do the periods of the arrival and departure of migrating birds vary in different years?

Because they depend entirely on the changes of the seasons. Thus, the meanest rustic, in regard to the summer birds of passage, is aware, that cold weather prevents the arrival of these messengers of spring; and that the early arrival of our winter birds of passage, indicates a proportionally early winter.

Why is the arrival of these summer birds to be partly prognosticated by the leafing or flowering of par ticular trees or plants?

Because the same circumstances of temperature which retard the birds, also check the progress of vegetation. As the state of vegetation depends on the temperature of the season, and the life of the insects, (the food of birds) on the state of vegetation, we may safely conclude, that the movements of the phytivorous (vegetable-eating) and insectivorous birds must be dependent on the condition of plants. Fleming.

Why is torpidity also called hybernation ?

Because it is evidently designed to afford animals protection against the cold of winter.

Actual torpidity in birds is very rare; yet the few instances on record establish the fact, while they point to the numerous resources of Nature in extreme cases, to preserve existence.

PART IV.