when a breeze ſuddenly ſpringing up from N.N.E. brought with it a thick fog, which concealed the ſun from our view for the ſpace of a quarter of an hour. It is very remarkable that the mercury in the barometer, inſtead of falling in conſequence of this change of weather, ſtood a line and a half higher than before, during the whole time that the fog continued. I dare not hazard any conjecture of my own in order to account for this phenomenon, which will appear the more aſtoniſhing to perſons converſant in natural philoſophy, as this circumſtance ought to have diminiſhed the elaſticity of the air inſtead of augmenting it: beſides, there was no reaſon to believe that the fog was occaſioned by the exploſion of any volcano.
On the 3d of January we enjoyed the ſpectacle of a lunar rainbow. This planet was encompaſſed, at ten o'clock in the evening, with two concentric circles, that preſented all the colours of the ſolar rainbow in reverſed order. The largeſt of the circles did not occupy more than five degrees in the ſky.
As this phenomenon, produced by the decompoſition of the rays of the moon, appeared between the planet and us, the priſmatical colours naturally preſented themſelves in an order the reverſe of what takes place in the ſolar rainbow;
becauſe
