(588)
I also wisht for some of the Glow-worms, with which I formerly made other Trials. For though I forgot not what operation the withdrawing of the Air by our Engine is wont to have upon living Creatures; yet that made me not forbear my wish, not only because of the different effect I have found the Engine to have on Insects in respect of other Animals, but because I am not of the opinion of those modern Writers, who will have the Light of Glow-worms depend altogether upon their Life, and end with it, But being not likely by my wishes to procure any new subject to make trials on, I thought fit at least to do what was in my power, and accordingly (to gratifie them, who, I presumed, would, if present, propose such a Trial) caused a piece of Iron to be forged, whose top was of the bigness of a Nutmeg; the rest being a stem, of an inch, or an inch and a half long, for which we provided a little Candlestick of Tobaccopipe-clay, which would not yield any smoak to fill and darken the Receiver. Then having heated the Iron red-hot, and placed it in this Clay, so that the round part was clearly protuberant, we convey'd it into the Receiver of white Glass, which was so placed, as to keep the sides at as good a distance as we could from the Iron, lest the excessive heat should (as we much feared it would) break the Glass. Then sending away the Candles, and making the Room dark, we hastily pumped out the Air, but could not perceive the withdrawing of it had any operation on the glowing Iron. And though it continued shining long enough to give us opportunity to pump out and let in the Air three several times, yet we could not observe, that the Air had any manifest operation one way or other. For though upon the withdrawing of the Air the Iron grew dimmer and dimmer, yet that I attributed to the cooling of it; and the rather, because having (to examine the conjecture) let in two or three times the Air, when the Receiver had been exhausted, there appeared no manifest increase of Light upon sudden admission of it.
Experiment VIII.
Having formerly in our Physico-Mechanical Experiments, about the Spring of the Air, observed, That the Air is thus far a Vehicle of Sound, that a Body but faintly sounding, being
