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them as a relief from more severe studies and duties, would never have thought of reprinting them, had not the great Comparative Anatomist named in the dedication, and other scientific friends, urged their re-publication, under the impression that when brought together, they might form a hand-book which might cherish, or even awaken a love for Natural History.
THE melody of birds finds its way to the heart of every one; but the cause that prompts the outpourings that make copse, rock, and river, ring again on a fine spring morning is more a matter of doubt with ornithologists than the uninitiated in zoological mysteries might suppose. Much has been written on this subject, but upon a consideration of the different opinions, aided by our own observations, we are inclined to think that love and rivalry are the two great stimulants, though we do not mean to deny that a bird may sing from mere gaiety of heart arising from finding itself in the haunts dear to it, and in the midst of plenty of the food it likes; to give vent, in short, to the buoyancy of spirit arising from general pleasurable sensations.
In this country the season of reproduction is undoubtedly that wherein
"The isle is full of pleasant noises, Sounds, and sweet airs that give delight."
And about ten weeks have been mentioned as the period during which most of our wild birds are in song. That there are exceptions to this rule there is no doubt. We have heard a wild thrush, one of the sweetest singers of his tribe, sing far into September, but we watched narrowly, and never could find that he had a mate. Then, again, we have the autumnal and even the winter notes of the robin long after the breeding season; and
caged birds, if well fed and kept, will sing the greatest part of the year.
Let us endeavour, before we proceed further, to give the reader some idea of the natural musical instrument with which the loud and complicated passages of song-birds are executed. The larynx is formed much after the fashion of some artificial wind-instruments, and consists of two parts; of these the first contains the proper rima glottidis, at the upper end, while the bronchial, or lower larynx, is furnished with another rima glottidis with tense membranes. The lower apparatus may be compared to the reed in a clarionet or hautboy, and the upper to the ventage or hole of the instrument that utters the note. Besides all this, it has been truly asserted that there is no part of a bird's structure impervious to air; and, as M. Jacquemin observes, it is the volume of air which birds can introduce into their bodies, and the force with which they can expel it, that solve the problem how so small a creature as a singing bird can be capable of sending forth notes so loud, and of warbling so long and so prodigally, without apparent fatigue. The muscles, whose province it is to regulate this wonderful wind-instrument, are proportionally strong and highly developed in the sex which is more peculiarly gifted with musical power. Thus John Hunter, on dissecting a cocknightingale, a cock and hen blackbird, a cock linnet, and a cock and hen chaffinch, found the muscles of the larynx to be stronger in the nightingale than in any other bird of the same size; and in all the instances where he dissected both cock and hen, he remarked that the same muscles were stronger in the cock. The rivalry with which some of these feathered songsters will sing against each other in captivity is well-known to bird-fanciers: and Bechstein observes, speaking of the Thuringian Canary birds, that there are some males which, especially in the pairing season, sing with so much strength and ardour, that they burst the delicate vessels of the lungs and die suddenly.
The Hon. Daines Barrington, who paid much attention to this subject, remarks that some passages of the song in a few kinds of birds correspond with the intervals of our musical scale; but that much the greater part of such a song is not capable of musical notations. He attributes this to the following causes:-First, because the rapidity is often so great, and it is also so uncertain where they may stop, that it is impossible to reduce the passages to form a musical bar in any time whatsoever; secondly, on account of the pitch of most birds being considerably higher than the most shrill notes of instruments of the greatest compass;— and lastly, because the intervals used by birds are commonly so minute that we cannot judge at all of them from the more gross intervals into which our musical octave is divided.