A Relation concerning the late Earthquake neer Oxford; together with some Observations of the sealed Weatherglass, and the Barometer both upon that Phænomenon, and in General.
This Relation was communicated by the excellently learned Dr. Wallis, as follows:
On the 19. of January 1665. Stylo Angliæ (or Jan. 29. 1666. stylo novo) at divers places neer Oxford, was observed a small Earthquake (as at Blechington, Stanton-St. Johns, Bril, &c.) towards evening. In Oxford it self, I doe not hear, that it was observ'd to be an Earthquake; yet I remember about that time (whether precisely then or not; I cannot say) I took notice of some kind of odde shaking or heaving I observed in my study, but did impute it to the going of Carts or Coaches, supposed to be not far off; though yet I did take notice of it, as a little differing from what is usual on such occasions; (and wondered the more, that I did not hear any:) But not knowing, what else to refer it to, I thought no more of it. And the like account I have had from some others in Oxford, who yet did not think of an Earth-quake; it being a rare thing with us. Hearing afterwards of an Earthquake observed by others; I looked on my Notes concerning my Thermoscope and Baroscope, to see if any alteration considerable had then happened.
My Thermoscope consists of a round large Glass, containing about half a pint or more; from whence issues a long Cylindrical neck of Glass, about two foot and a half in length, and less than a quarter of an inch diameter; which neck was hermetically sealed at the top, to exclude communication with the External Air; but before the sealing of it, the whole Glass was filled with Spirit of Wine (tinged with Cochineel, to make it the more discernable to the Eye) so warmed, that it filled the whole content of the Glass; but afterwards, as it cooled, did so subside, as to leave a void space in the upper part of the Neck. Which Instrument, so prepared, doth by the rising or falling of the tinged liquor in the neck (consequent upon the expanding or contracting of the whole liquor contained in it and the Ball below) give a very nice account of the Temperature of the Air,
as to Heat or Cold: Even so nice, as that my being or not being in my Study I find to vary its hight sometimes almost a quarter of an inch.
My Baroscope, I call another Instrument for estimating the Weight or Pressure of the Incumbent Air, consisting of a long Glass-tube of about 4. foot in length, and about a quarter of an inch Bore: which tube (hermetically sealed at the one end) being filled with Quicksilver (according to the Torricellian Experiment) is inverted, so as to have the open end of it immersed in Stagnant Quicksilver, contained in a larger Glass under it, exposed to the pressure of the outward Air: Out of which open end (after such immersion) the Quicksilver in the Tube being suffered to run out, as much as it will, into the Stagnant Quicksilver, in which that mouth or open end is immersed, there is wont to remain (as is commonly known to those acquainted with this Experiment) a Cylinder of Quicksilver suspended in the Tube, about 28, 29, or 30. inches high; measuring from the surface of the Stagnant Quicksilver perpendicularly; (but more or less, within such limits, according as the Weight or Pressure of the Air incumbent on the External Stagnant Quicksilver exposed to it, is greater or less:) leaving the upper part of the Tube void. (Both which Instruments being the contrivance of the Honourable Robert Boyle, they are by him more particularly described in his Physico-Mechanical Experiments touching the Air, Exper. 17. and 18. and in his Thermometrical Discourses, premised to his History of Cold.)
Now, according to both these Instruments, having kept a daily Register of Observations for more than a whole year (saving when I have been for some short time absent from home) I find my Notes for that day to be these.
| January. Day. Hour. | Thermoscope. inches. | Baroscope. inches. | 1665/6. | |
| 19. 8. Morn. | 141/16. | 29½. | Hard frost. | Close. |
| 4. Even. | 14⅜. | 29¼. | Hard frost. | Cloudy. |
| 9. Even. | 14¾. | 29¾. | Rain. | Wind |
| 20. 8. Morn. | 15¼. | 28¾. | Sunshine. | Wind. |
So that, there being in the morning (January 19.) a hard frost (which began the day before about 4. of the Clock in the