The quicksilver having fallen to a lower point in the barometer in the course of the last month than any person, probably, remembers to have seen it at, in the neighbourhood of London, a short account of the circumstances may, perhaps, not be unacceptable to the Royal Society. On the evening of December 24, I found the barometer at 28.20 in. the wind being moderate at S. E., with steady rain, the temp. without, at 8 p. m. 45°. Water boiled freely at 210°. Finding the depression still to continue, I took a portable barometer, on Sir H. Englefield’s construction, and having ascertained its height to be, at .11 p. m., 27.96, I set it up in my chamber on the first floor. At 5 a. m. the 25th, this instrument gave 27.83 in., and I have reason to think it did not go much lower: the rain had ceased early in the night, and it had become somewhat star-light, with a calm air, and hazy cirrostrati above: soon after five, however, the wind rose again, bringing some rain, apparently from N. W., but there was no tempest that I had opportunity to observe, though it might have blown hard during the few hours I slept. The pencil of my clock barometer travelled precisely to two-tenths below the bottom of the scale, having made a continuous downward sweep of nearly an inch and four-tenths in 24 hours: it appears to have turned to rise abruptly, and by 8 a. m. was again on the point of passing 28 inches. In the 24 hours preceding this time, there had fallen eight tenths of an inch of rain; in the 24 hours following it there fell none, nor was the wind, which blew from S. W., at all strong; indeed it was calm all the middle part of the day, with sunshine and cirrus above: evaporation was very perceptible, and the night, up to 10 p. m. starlight. The barometer, at 8 p. m. the 25th, was at 28.40 in. In the early morning of the 27th, not having yet reached 29 in., it turned to fall again, with the wind at S. and S. W., after S. E.: we had again some heavy rain with hail about noon, and by midnight the quicksilver reached 28.07, or .06 in., where it stood, or rather made minute oscillations, during the 12 hours following , a thing I should scarcely have thought possible in our climate.