Letter 0974

[fol. 419] Sr Upminster Jan: 17 1704/5 The days being short, & the ways dirty hinders me from the great pleasure & satisfaction of your Meetings. Being therefore not well able to some my self, I have sent you the what the Society ordered me to give them an account of, viz my Obser- vations of the Vibrations of Pendulums in Vacuou, & the Air. I am now very busy in setteling the business of the Flight of Sounds, which may be of good use, when I have determined these following Enquiries, wch I have drawn up for myself which I have send you in the same confused manner in wch they came into my mind. Or if you; or out President (wch I suppose is Mr Newton still) or the Society, would be pleased to add any other Enquiries, I shall take it as a great favour to re- ceive them, & will endeavour wth all care, diligence, & fidelity to answer them. My Enquiries are 1. What Space Sounds fly in a Second or any determinate Time? 2. Whether a Gun Towards or Fromwards be heard the same Time? 3. Whether the Motion of Sounds be the same in the Night as Day? 4. Whe- ther in all States of the Atmosphere, when the ☿ [Mercury] is high or low, theyr motion be the same? 5. Whether a Great & Small Gun be heard in the same Time? 6. Whether in all Elevations of the Gun, as ho- rizontal, at 10, 20, 45 or 90gr the Sound be heard in the same Time? 7. Whether Favouring or Countrary Winds accelerate or retard, or how affect a Sound? 8. Whether they move Swifter in a Calm than a Strong Wind, as some assert? 9. Whether a Strong Wind blowing across accelerateth or retardeth? 10. Whether they Move swifter at first, & slower when near spent, as in other violent motions? 10. [sic] Whether they are not rather Equable, as whether in half the time they fly not half the Space, in a quarter a quarter or? The first, & principall Enquiry, being what the most curious & celebrated Authors have differed about (& not one of them in the right), put me first upon endeavours to settle this matter. And therefore altho I knew the Florentine Academy have determined some of these things, yet I was willing to try over their experiments, especially because I have opportunities of doing it at much greater dis- tances than theirs were tryed at. I have allmost satisfied my self about all the former Enquiries, which when I have fully done I will impart it to the Society. I only want a few Guns from the Tower or some such large distance (which I could see in the Evening) to fully con- firm what I have already done. There were large spots on the Sun the beginning of this month, wch I measured exactly every day that I could see the Sun. They are now on the other side of the Sun, but when I last saw them, seemed Spiss enough to bear another Revolution of the Sun. I expect to see them again, or no doubt Facula in their place, the beginning of next week. For I have often observed, since spots have been on the Sun frequently the last Year or two, That yr Maculae always end in Facula: which to me is an Argument that the Spots are a great Smoak or Smother mafe at some new by the Eruptions of some new Volcano, or what else you will call it; & that when that smoak is past, the Volcano burneth clear, & so maketh those there lucid, golden appearances on the Suns Dish, wch goe by ye name of Facula. I have not time to add any more, the messenger yt carrieth this being just come, but only yt I am very affectionately Your humble servt Wm Derham