as to think all those things the productions of chance? Certainly, either their Ratiocination must be extremely depraved, or they did never attentively consider and contemplate the Works of the Almighty.
Observ. XXXVIII.Of the Structure and motion of the Wings of Flies.
THe Wings of all kinds of Insects, are, for the most part, very beautifull Objects, and afford no less pleasing an Object to the mind to speculate upon, then to the eye to behold. This of the blue Fly; among the rest, wants not its peculiar ornaments and contrivances; it grows out of the Thorax, or middle part of the body of a Fly, and is seated a little beyond the center of gravity in the body towards the head, but that Execentricly is curiously balanc’d; first, by the expanded Area of the wings which lies all more backwards then the root, by the motion of them, whereby the center of their vibration is much more backwards towards the tail of the Fly then the root of the wing is. What the vibrative motion of the wings is, and after what manner they are moved, I have endeavoured by many trials to find out: And first for the[errata 1] manner of their motion, I endeavoured to observe several of those kind of small spinning Flies, which will naturally suspend themselves, as it were, pois’d and Ready in one place of the air, without rising or falling, or moving forwards or backwards; for by looking down on those, I could by a kind of faint shadow, perceive the utmost extremes of the vibrative motion of their wings, which shadow, whil’st they so endeavoured to suspend themselves, was not very long, but‘when they endeavour’d to fly forwards, it was somewhat longer; next, l tried it, by fixing the leggs of a Fly upon the top of the stalk of a feather, with Glew, Wax, &c. and then making it endeavour to flie away; for being thereby able to view it in any posture, l collected that the motion of the wing was after this manner. The extreme limits of the vibrations were usually somewhat about the length of the body distant from one another, often times shorter, and sometimes also longer; that the formoft limit was usually a little above the back, and the hinder somwhat beneath the belly; between which two limits, if one may ghess by the sound, the wing seem’d to be mov’d forwards and backwards with an equal velocity: And if one may (from the shadow or faint representation the wings afforded, and from the consideration of the nature of the thing) ghess at the posture or manner of the wings moving betweeen them, it seem’d to be this: The Wing being suppos’d placed in the upmost limit, seems to be put so that the plain of it lies almost horizontal, but onely the forepart does dip a little, or is somewhat more deprest; in this position is the wing vibrated or mov'd to the lower limit, being almost arrived at the lower limit, the hinder part of the wing moving somewhat faster then the
Errata
