The works of the Honourable Robert Boyle, Esq., epitomiz'd by Richard Boulton ... ; illustrated with copper plates.

ƲSE III. To discover and compare the Changes of the Tem∣perature of the Air made by Winds strong or weak; frosty, snowy and other Weather.

THAT the Spunge in the Wind or Sun loses considerably of it's Weight, [Use 3] I my self have experienc'd, a Spunge hanging in the Sun in January, having lost a 24th Part of it's Weight, after it had been 3 quarters of an hour expos'd to it; and making use of half an Ounce of Sheeps Leather instead of Spunge, this being hung in the Wind, only lost 1/18 of it's Weight in an hour.

But tho' it be possible thus to make Ob∣servations of Particular Winds; yet it requires a great deal of Caution, as well as Skill in Phy∣sick and Cosmography, in forming Rules for the observing of the Qualities of other Bodies, since Winds which come from the same Quarters in several Countries have different Qualities; for tho' North Winds in the Winter, are generally attended with Frost, yet at the Famous Port of Archangel a Thaw accompany'd it; the Reason of which seems to be no other than, that the Northern Wind coming a long way over the Northern Seas, does not acquire such a Disposi∣tion as the South Wind, which passes over a large Tract of Frozen Land. And it is observ'd in Aegypt, that the North Winds which are else∣where drying, are there moist, which is attested by Mr. Sands in his Travels into Aegypt, lib. 6. Cap. 8. Sect. 3. And Monsieur de Serres affirms,

that about the Quarters of Tholouze, the South Wind dries, and the North Wind brings Rain; yet from Narbonne to Lyons, all over Provence and Dauphinè it is quite otherwise.

But, besides that on this account Winds from the same Quarters may differently affect the Hygroscope; It's Operation may be considerably diversify'd, as it blows vehemently or slowly over the same Country; for tho Wind would rather increase the Weight of a Hygroscope if mov'd slowly, yet by a more vehement Agita∣tion, several moist Particles in the Spunge are dissipated and dispersed. To these Observa∣tions I shall add the following, Viz. that frosty Weather hath been observ'd to make the Hy∣groscope grow lighter towards Night, and that snowy Weather increas'd the Weight of it, as likewise misty and foggy Weather.

But what is more strange is, that on a Sun∣shiny day, the Spunge hath preponderated up∣on the passing by of a Cloud; but as soon as that was gone, regain'd it's Aequilibrium; and I have observ'd, that when the Air hath grown heavier, the Hygroscope hath grown lighter, as if those Terrestrial Effluvia which increase the Weight of the Air were unfit to be imbib'd into the Pores of the Spunge; wherefore at such times it may not be amiss to take notice; whether any, and if any, what kind of Meteor, as Wind, or Rain or Hail, or in the Winter, Snow or Frost, will commonly be signifi'd or produc'd.