in so short a time seem'd very considerable, being little less than 6 ounces in 24 hours, from so small a Surface as a Circle of 8 inches Diameter. To reduce this Experiment to an exact Calculus, and determine the thickness of the Skin of Water that had so evaporated, I assume the Experiment alledg'd by Dr. Edward Bernard to have been made in the Oxford Society, viz. That the Cube-foot English of Water weighs exactly 76 Pounds Troy ; this divided by 1728, the number of Inches in a Foot, will give 253⅓ grains, or ½ ounce 13⅓ grains for the weight of a Cube-inch of Water; wherefore the weight of 233 grains is 233 ⁄ 253 or 35 Parts of 38 of a Cube-inch of Water. Now the Area of the Circle whose Diameter is 7 9 ⁄ 10 Inches, is 49 square Inches: by which dividing the Quantity of Water evaporated, viz. 35 ⁄ 38 of an Inch, the Quote 35 ⁄ 1862 or 1 ⁄ 53 shews that the thickness of the Water evaporated was the 53d part of an Inch; but we will suppose it only the 60th part, for the Facility of Calculation. If therefore Water as warm as the Air in Summer, exhales the thickness of a 60th part of an Inch in two hours from its whole Surface, in 12 hours it will exhale the ⅒ of an Inch; which Quantity will be found abundantly sufficient to serve for all the Rains, Springs, and Dews; and account for the Caspian Sea, being always at a stand, neither wasting nor overflowing; as likewise for the Current said to set always in at the Streights of Gibralter , tho' those Mediterranean Seas receive so many and so considerable Rivers.
To estimate the Quantity of Water arising in Vapours out of the Sea, I think I ought to consider it only for the time the Sun is up, for that the Dews return in the Night, as much if not more Vapours than are then emitted;