MISTS are observed to happen when the Mercury in a Barometer is either very low of very high. They happen when it is high after the Region of the Air has continued calm a good while, and in the mean time a great Abundance of Vapours and Exhalations have been accumulated, making the Air dark by their quantity, and the disorderly Disposition of their parts. They happen when the Mercury is low, sometimes because the Rarity of the Air renders it unable to sustain the Vapours, which therefore descend and fall through it. BUT none of these Cases agree with the Observation at the Head of the Page, and therefore to form a true judgment of the Weather, we must distinguish between them and the Case which explains the Observation. X. _If in the new Moon._----Rain in the old. WHEN Exhalations rise copiously from the Earth into the Region of the Air, and the Air itself is in a proper Disposition, they ascend to a great Height, and continue a long Time before they are condensed, which accounts very clearly and philosophically for the Interval of fair Weather between the rising of these Mists, and their falling down again in Showers. Their ascending about Sun-rise is a Proof that the Air is thin, but at the same time of a Force sufficient to sustain them, since if the Mists were not specifically lighter than the Air itself they could not ascend. WHEN the Moon is at the full, and such Exhalations rise plentifully, the time necessary for them to float in the Atmosphere, before they are condensed into Clouds and Rain, extends, generally speaking, beyond the Period of that Moon, and therefore the Observation directs us to expect _fair Weather_. XI. _If in the old._----Rain in the New. BUT as it is observed not only in this Climate, but all the World over, that great Changes of Weather happen near the Change of the Moon, it follows that this is the Season when these Exhalations that ascend so plentifully at Sun-rising are condensed, and consequently is the Season when we ought to expect _Rain_. IF therefore the Exhalations rise in the new Moon, it is a Sign that the Air is in a fit disposition to sustain and support them for a considerable Time, and therefore we have Reason to expect that they should continue floating till the next regular change of Weather, that is, till the old of the Moon, or rather till towards the next Change, and therefore the Observation is very cautiously and very properly worded, directing us to expect Rain _in_ the old, and _in_ the new, and not _at_ the old or new, because it is observed that these Changes of Weather happen not exactly _at_ the Change of the Moon, but a Day or two before or after, of which the Reader will meet with many Examples in Captain _Dampier's_ History of Winds and Storms at Sea. XII. WINDS. _Observe, that in eight Years' Time there is as much South West Wind, as North East, and consequently as many wet Years as dry._