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

ƲSE VI. To keep a Chamber at the same Degree, or an assigned Degree of Dryness.

THIS may easily be done by observing the Aequilibrium of the Spunge, [Use 6] and accord∣ingly increasing or diminishing the Fire. I have observ'd a notable Difference in the Weight of a Hygroscope, when the Room hath been wash'd, tho a good Fire was kept in it to dry it pre∣sently.

To these Observations I shall add, that I have sometimes taken notice, that the Hygroscope hath not answer'd our Expectation, as at other times; whether the Air, at that, abounded with other Effluviums, which render'd the moist Par∣ticles of it, more unfit to be imbib'd by the Pores of the Spunge, I shall not determine; nor whe∣ther in time, Hygroscopes may not help us to dis∣cover the Nature of different Effluviums, such as those of Spirit of Wine, Chymical Oyls, &c. Nor shall I undertake to determine, whether this Instrument joyn'd with the Baroscope and some others, may not help to give us a foresight of some Constitutions of the Air which precede Diseases, Hurricanes, Earthquakes, or Inunda∣tion; especially of those Accidents which de∣pend on the Air's being overcharg'd with Exha∣lations and other moist Vapours; as well as it does of a shower of Rain.

To conclude this Chapter, I shall intimate, that tho' in these Matters it be perhaps impossi∣ble to form Hypotheses, which can in no Points

be call'd in Question, yet the Theory may be as good as can, by a wise Man, be expected, in so mutable a Subject as the Air; and therefore they ought not to be slighted or suddenly laid aside, since several Accidents may intervene in the Air, on which those may depend. As we know, tho' Tides generally Ebb and Flow, so as to answer the Theory given of them, yet by fierce Winds and great Land-Floods, the regular Course of them hath often been alter'd.