An Advertisement

veral Flies, I thought fit to transcribe what Dr. Hook says concerning the same in his Micrographia, and to give the Figure thereof, as it is by him described. See Lit. Q. in regard the Book is very scarce, Micrographia, Observ. 38, pag. 173. 'Whilst I was examining and considering the curious Mechanism of the Wings, I observed that under the Wings of most kinds of Flies, Bees, &c. there were placed certain Pendulums, or extended drops (as I may 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 guess, that there was some excellent use as to the Regulation of the Motion of the Wings, and did fancy 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 supposed that they might be for some use in Respiration, which for many Reasons I suppose those Animals to use; and methought it was not very improvable, 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 Analogous 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. An ADVERTISEMENT. The Ingenious are desired, That if they have any loose Papers relating to the same Design with those of Sir William Petty's, Printed in this Transaction, they will please to communicate them, which Favour shall be acknowledged by the like Communications by the Publisher. LONDON, Printed for, and Sold by S. Smith and B.Watford, Printers to the Royal Society, at the Princes Arms in St. Paul's Church-yard. 1693.