Page:Philosophical Transactions - Volume 004.djvu/231

 (which is the thing, for which I mention it) the Noise upon these knocks was not such a dull noise, as Quick-silver or other Liquids use to make in the open Air, by dashing against Glass or Ice, or other such hard Bodies; but such a hard smart noise, as hard Metals use to make by knocking one against the other; or, as if this Ice had been so knock'd by a solid piece of Iron or other Metal of such a bigness. Which difference of noise from what would have been in the open Air (where the intermediate air must first have been beat away, before the Quick-silver could strike the Ice, and thereby the stroke of the liquid body obtunded or broken,) I attribute to that voidness of Air, which was between the Ice and the distant Quick-silver. And I remembered presently, that the Honourable Mr. Boyle had formerly shew'd me an Experiment, very like this, upon another occasion: which made me the readier to take notice of this; and I did it several dayes successively. But when, by applying the heat of a Candle to the side of the Glass, I had melted this Ice, I found (as I expected) that within a little time the Quick-silver was risen about a sixteenth part of an Inch above what it was before; which the freezing of the Water had till then hindred it from doing.

My Thermoscope, or Sealed Weather-glass, (which, having no communication with the Open Air, and so not being affected with its Weight, gives accompt but of its Heat and Cold;) hath, this last Frost, been much lower than I ever have known it, upon five years constant Observation. Which proceedeth partly from the Extremity of the Cold, more than ordinary; and partly from the inclosed Liquor (being Spirit-of Wine, tinged with Cochineal,) growing less spirituous.

It was first made in Decemb. 1664, In the Months of January, and of February following, we had very smart frosts, more cold than ordinary; when yet the lowest mark, to which the liquor did subside (in very hard frosts, and very cold wind,) was at inches 12¼: (at which time, 14½ was frost certain, and sometimes at 15 and at 15½:) The in Summer following 1665, was usually at 20, 21, 22,  or thereabouts; but in some very hot