former, the Area of the wing begins to dip behind, and in that posture seems it to be mov’d to the upper limit back again, and thence back again in the first posture, the former part of the Area again, as it is moved downwards by means of the quicker motion of the main stem which terminates or edges the forepart of the wing. And these vibrations or motions to and fro between the two limits seem so swift, that ’tis very probable (from the sound it affords, if it be compar’d with the vibration of a musical string, tun'd unison to it) it makes many hundreds, if not some thousands of vibrations in a second minute of time. And, if we may be allow'd to ghess by the sound, the wing of a Bee is yet more swift, for the tone is much more acute, and that, in all likelihood, proceeds from the exceeding swift beating of the air by the small wing. And it seems the more likely too, because the wing of a Bee is left in proportion to its body, then the other wing to the body of a Fly; so that for ought I know, it may be one of the quickest vibrating spontaneous motions of any in the world; and though perhaps there may be many Flies in other places that afford a yet more shrill noise with their wings, yet ’tis most probable that the quickest vibrating spontaneous motion is to be found in the wing of some creature. Now, if we consider the exceeding quickness of these Animal spirits that must cause these motions, we cannot chuse but admire the exceeding vividness of the governing faculty or Anima of the Insect, which is able to dispose and regulate so the the motive faculties, as to cause every peculiar organ, not onely to move or act so quick, but to do it also so regularly.
Whil’st I was examining and considering the curious Mechanism of the wings, I observ’d that under the wings of most kind of Flies, Bees, &c. there were plac’d certain pendulums or extended drops (as I may so call them from their resembling motion and figure) for they much resembled a long hanging drop of some transparent viscous liquor; and I observed them constantly to move just before the wings of the Fly began to move, so that at the first sight I could not but ghess, that there was some excellent use, as to the regulation of the motion of the wing, and did phancy, that it might be something like the handle of a Cock, which by vibrating to and fro, might, as ’twere, open and shut the Cock, and thereby give a passage to the determinate influences into the Muscles; afterwards, upon some other trials, I suppos’d that they might be for some use in respiration, which for many reasons I suppose those Animals to use, and, me thought, it was not very improbable, but that they might have convenient passages under the wings for the emitting, at least, of the air, if not admitting, as in the gills of Fishes is most evident; or, perhaps, this Pendulum might be somewhat like the staff to a Pump, whereby these creatures might exercise their Analogus lungs, and not only draw in, but force out, the air they live by: but these were but conjectures, and upon further examination seem’d less probable.
The fabrick of the wing, as it appears through a moderately magnifying Microscope, seems to be a body consisting of two parts, as is visible in the 4.Figure of the 23.Scheme; and by the 2.Figure of the 26.Scheme; the one is
