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Hooke, Robert, 1635-1703 / Micrographia: or some physiological descriptions of minute bodies made by magnifying glasses : with observations and inquiries thereupon
(MDCLXVII [1667])

Observ. XXXVIII. Of the structure and motion of the wings of flies,   pp. 172-174


Page 172


              M    IC RO GRA P H IIA'
as to think all thofe things the produftions of chance? Certainly, ei.
ther their Ratiocination muft be extremely depraved,or they did never
attentively confider and contemplate the Works of the Al-mighty.
Obferv. X X X V I I I. Of the Stru~iure and motion of the WTings
   of Flies.
THe Wings of all kinds of InfCdts, are, for the moft part, very
    beautifull Objefts, and afford no lefs pleafing an Objedt to the mind
to Speculate uponthen to the eye to behold. This of the blue Fly,among
the reffh wants not its peculiar- ornaments and contrivances ; it grows
ont of the 7 horax, or middle part of the body of a Fly, and is feated a
little beyond the center of gravity in the body towards the head, but
that Excentricl is curioufly balanc'd ; firft, by the expanded Area ofthe
wings which lies all more backwards then the root, by the motion of
them,whereby the center oftheir vibration is much more backwards to-
wards the tail of the Fly then the root of the wing is. What the vibra-
tive motion of the wings is, and after what manner they are moved, I
have endeavoured by many trials to find out: And for the firft manner
oftheir motion, I endeavoured to obferve feveral of thofe kind of fmall
fpinning Flies, which will naturally ifpend themfelves, as it were, pois'd
and fteady in one place of the air, without rifing or falling, or moving
forwards or backwards; for by looking down on thofe, I could by a kind
of faint fhadow, perceive the utmoft extremes of the vibrative moti-
on of their wings, which fhadow, whiled they fo endeavoured to fufpend
themfelves, was not very long, but when they endeavour'd to flie for-
wardsit was fomewhat longer ; nextI trieditby fixing the leggs of a Fly
upon the top ofthe flalk of a feather, with Glew, Wax, &-c. and then
making it endeavour to [lie away ; for being thereby able to view it in
any poflure, I collected that the motion of the wing was after this man-
ner. I he extreme limits of the vibrations were ufually fomewhat about
the length of the body diftant from one another, oftentimes fhorterand
fometimes alfo longer; that the formnft limit was ufuallv a little above
the backand the hinder fomnwhat beneath the belly ;between which two
limits, if one may ghefs by the found, the wing feem'd to be mov'd for-
wards and backwards with an equal velocity: And if one may (from the
fhadow or faint reprefentation the wings aflbrded, and from the confide-
ration of the nature of the thing ) ghefs at the poflure or maimer
of the wings moving hetweeen them, it feem'd to be this: The wing
being fUppos'd placed in the upmoft limit, feems to be put fo that the
  plain of it lies almoff horizontal, but onely the forepart does dip a little,
  or is fomewhat more depreft; in this pofition is the wing vibrated
  or mov'd to the lower limit, being almoft arrived at the lower li-
  mit, the hinder part of the wing moving fomewhat fafter then the
                                                             former,


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