"Now vows connubial chain the plighted pair, And join paternal with maternal care; The married birds with nice selection cull Soft thistle-down, gray moss, and scattered wool, Line the secluded nest with feathery rings, Meet with fond bills, and woo with fluttering wings. Week after week, regardless of her food, The incumbent Linnet warms her future brood; Each spotted egg with ivory lips she turns, Day after day with fond expectance burns, 350 Hears the young prisoner chirping in his cell, And breaks in hemispheres the obdurate shell. Loud trills sweet Philomel his tender strain, Charms his fond bride, and wakes his infant train; Perch'd on the circling moss, the listening throng Wave their young wings, and whisper to the song. [Footnote: _The incumbent Linnet_, l. 348. The affection of the unexperienced and untaught bird to its egg, which induces it to sit days and weeks upon it to warm the enclosed embryon, is a matter of great difficulty to explain; See Additional Note IX. on Storge. Concerning the fabrication of their nests, see Zoonomia, Sect. XVI. 13. on instinct.] [Footnote: _Hears the young prisoner_, l. 351. The air-vessel at the broad end of an incubated egg gradually extends its edges along the sides of the shell, as the chick enlarges, but is at the same time applied closer to the internal surface of the shell; when the time of hatching approaches the chick is liable to break this air-bag with its beak, and thence begin to breathe and to chirp; at this time the edges of the enlarged air-bag extend so as to cover internally one hemisphere of the egg; and as one half of the external shell is thus moist, and the other half dry, as soon as the mother hearing the chick chirp, or the chick itself wanting respirable air, strikes the egg, about its equatorial line, it breaks into two hemispheres, and liberates the prisoner.] [Footnote: _And whisper to the song_, l. 356. A curious circumstance is mentioned by Kircherus de Musurgia, in his Chapter de Lusciniis. "That the young nightingales, that are hatched under other birds, never sing till they are instructed by the company of other nightingales." And Johnston affirms, that the nightingales that visit Scotland, have not the same harmony as those of Italy, (Pennant's Zoology, octavo, p. 255), which would lead us to suspect, that the singing of birds, like human music, is an artificial language rather than a natural expression of passion.]