MUSICAL TRUMPET.

THE Musical Trumpet is a wind instrument which sounds by pressing the closed lips to the small end, and forcing the wind through a very narrow aperture between the lips. This is one of the most ancient of musical instruments, and has appeared in all nations in a vast variety of forms. The conch of the savage, the horn of the cow-herd and of the postman, the bugle horn, the lituus and tuba of the Romans, the military trumpet, and the trombone, the cor de chasse or French horn-are all instruments winded in the same manner, producing their variety of tones by varying the manner and force of blowing. The serpent is another instrument of the same kind, but producing part of its notes by means of holes in the sides.

Although the trumpet is the simplest of all musical instruments, being nothing but a long tube, narrow at one end and wide at the other, it is the most difficult to be explained. To understand how sonorous and regulated undulations can be excited in a tube without any previous vibration of reeds to form the waves at the entry, or of holes to vary the notes, requires a very nice attention to the mechanism of aerial undulations, and we are by no means certain that we have as yet hit on the true explanation. We are certain, however, that these aerial undulations do not differ from those produced by the vibration of strings; for they make strings resound in the same manner as vibrating cords do. Galileo, however, did not know this argument

for his assertion that the musical pitch of a pipe, like that of a cord, depended on the frequency alone of the aerial undulations; but he thought it highly probable, from his observations on the structure of organs, that the notes of pipes were related to their lengths in the same manner as those of wires, and he expressly makes this remark. Newton, having discovered that sound moved at the rate of about 960 feet per second, observed that, according to the experiments of Mr. Sauveur, the length of an open pipe is half the length of an aerial pulse. This he could easily ascertain by dividing the space described by sound in a second by the number of pulses.

Daniel Bernoulli, the celebrated promoter of the Newtonian mechanics, discovered, or at least was the first who attentively marked, some other circumstances of resemblance between the undulations of the air in pipes and the vibrations of wires. As a wire can be made, not only to vibrate in its full length, sounding its fundamental note, but can also be made to subdivide itself, and vibrate like a portion of the whole, with points of rest between the vibrating portions, when it gives one of its harmonic notes; so a pipe can not only have such undulations of air going on within it as are competent to the production of its fundamental note, but also those which produce one of its harmonic notes. Every one knows that when we force a flute, by blowing too strongly, it quits its proper note, and gives the octave above. Forcing still more, produces the 12th. Then we can produce the double octave or 15th, and the 17th major, &c. In short, by attending to several circumstances in the manner of blowing, all the notes may be produced from one very long pipe that we produce from the trumpet marine, and in precisely the same order, and with the same omissions and imperfections. This alone is almost equivalent to a proof that the mechanism of the undulations of air in a pipe is analogous to that of the vibrations of an elastic cord. Having with so great success investigated the mechanism of the partial vibrations of wires, and also another

kind of vibrations which we shall mention afterwards, incomparably more curious and more important in the philosophy of musical sounds, Mr. Bernoulli undertook the investigation of those more mysterious motions of air which are produced in pipes; and in a very ingenious dissertation, published in the memoirs of the Academy of Paris for 1762, &c. he gives a theory of them, which tallies in a wonderful manner with the chief phenomena which we observe in the wind instruments of the flute and trumpet kind. We are not, however, so well satisfied with the truth of his assumptions respecting the state of the air, and the precise form of the undulations which he assigns to it; but we see that, notwithstanding a probability of his being mistaken in these circumstances (it is with great deference that we presume to suppose him mistaken), the chief propositions are still true; and that the changes from note to note must be produced in the order, though perhaps not in the precise manner, assigned by him.

It is by no means easy to conceive, with clearness, the way in which musical undulations are excited in the various kinds of trumpets. Many who have reputation as mechanicians, suppose that it is by means of vibrations of the lips, in the same manner as in the hautboy, clarionette, and reed pipes of the organ, where the air, say they, is put in motion by the trembling reed. But this explanation is wrong in all its parts; even in the reed pipes of an organ, the air is not put in motion by the reeds. They are indeed the occasions of its musical undulation, but they do not immediately impel it into those waves. This method (and indeed all methods but the vibrations of wires, bells, &c.) of producing sound is little understood, though it is highly worthy of notice, being the origin of animal voice, and because a knowledge of it would enable the artists to entertain us with sounds hitherto unknown, and thus add considerably to this gift of our Bountiful Father, who has shewn, in the structure of the larynx of the human species, that he intended that we should enjoy the pleasures

of music as a laborum dulce lenimen. He has there placed a micrometer apparatus, by which, after the other muscles have done their part in bringing the glottis nearly to the tension which the intended note requires, we can easily, and instantly, adjust it with the utmost nicety.

We trust, therefore, that our readers will indulge us while we give a very cursory view of the manner in which the tremulous motion of the glottis, or of a reed in an organ pipe, produces the sonorous undulations with a constant or uniform frequency, so as to yield a musical note.

If we blow through a small pipe or quill, we produce only a whizzing or hissing noise. If, in blowing, we shut the entry with our tongue, we hear something like a solid blow or tap, and it is accompanied with some faint perception of a musical pitch, just as when we tap with the finger on one of the holes of a flute when all the rest are shut. We are then sensible of a difference of pitch, according to the length of the pipe; a longer pipe or quill giving a graver sound. Here, then, is like the beginning of a sonorous undulation. Let us consider the state of the air in the pipe: It was filled by a column of air, which was moving forward, and would have been succeeded by other air in the same state. This air was therefore nearly in its state of natural density. When the entry is suddenly stopped by the tongue, the included air, already in motion, continues its motion. This it cannot do without growing rarer, and then it is no longer a balance for the pressure of the atmosphere. It is therefore retarded in its motion, totally stopped (being in a rarefied state), and is then pressed back again. It comes back with an accelerated motion, and recovers its natural density, while the state of rarefaction goes forward through the open air like any other aërial pulse. Its motions are somewhat, but not altogether, like that of a spiral wire, which has been in like manner moving uniformly along the pipe, and has been stopped by something catching hold of its hindermost extremity. This spring, when thus catched behind, stretches it