Page:Philosophical Transactions - Volume 004.djvu/226

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(1113)

Some Observations

Concerning the Baroscope and Thermoscope, made and communicated by Doctor I. Wallis at Oxford, and Dr. I Beale at Yeovil in Somerset, deliver'd here according to the several dates, when they were imparted.

Dr. Beale in those Letters of his dated Decemb. 13. Decemb. 29., 1669, and Januar. 3, 1669/70.

HAving not look'd upon my Barometer a long time, I did by meer chance call my Eye on it upon Munday last, Decem. 13. 1669. about one of the Clock p. m.; and just then I saw the Quicksilver higher, than I dare positively affirme that it was ever since I had it in my custody, viz. since May 28. 1664. It was compleatly and apparently above half an inch more than thirty inches high. I called younger men to examine it over and over very carefully, by a measure, taken exactly from the standard-foot of London, both in Brass and in Box. They measured it often from that time, which was Munday, and late in the night of that day; then on Tuesday morning early; oft-times in the day, and late at Night: also some part of Wednesday. In all which time, when it was lowest, it was (as I said at first) compleatly 30½ inches; sometimes manifestly higher to the eigth or tenth part of a inch.

For this Baroscope I have two Glass-canes in one vessel of stagnant Quicksilver. They are of equal length, not fully two inches higher, than the Mercury ascended, and no Bolt-head to either of the Glasses. The one hath not been moved these two or three years, and hath a tincture of the Mercury on the empty top, as from the steams of the Mercury in some hot Summer; the other Glass was placed there about a year and an half agoe. This hath no tincture on the top. Both agreed in this Indication, as others affirme; but, to my Eye, in the latter Glass the Quicksilver seemed to be something higher.

The Weather was at first discovery very bright and clear: a gentle frost, by the Suns heat melting. The Air was very silent, no wind stirring, and the curious Wind-vane noting, that the wind was directly in the East all the first day (Decemb. 13;)on