Note e — BOOK II.

That Springs have their Origine from the Sea, and not from Rains and Vapours, among many other strong Reasons, I conclude from the Perennity of divers Springs, which always afford the same quantity of Water. Of this sort there are many to be found every where. But I shall, for an Instance, single out one in the Parish of Upminster, where I live, as being very proper for my purpose, and one that I have had better Opportunities of making Remarks upon above twenty Years. This in the greatest Droughts is little, if at all diminished, that I could perceive by my Eye, although the Ponds all over the Country, and an adjoining Brook have been dry for many Months together; as particularly in the dry Summer Months of the Year 1705. And in the wettest Seasons, such as the Summer and other Months were, preceding the violent Storm in November 1703. (Vid. Philos. Trans. Nᵒ. 289.) I say, in such wet Seasons I have not observed any Increment of its Stream, excepting only for violent Rains falling therein, or running down from the higher Land into it; which discoloureth the Waters oftentimes, and makes an increase of only a Day’s, or sometimes but a few Hours Continuance. But now, if this Spring had its Origine from Rain and Vapours, there would be an increase and decrease of the one, as there should happen to be of the other: As actually it is in such temporary Springs as have undoubtedly their Source from Rain and Vapours.

But besides this, another considerable Thing in this Upminster Spring (and Thousands of others) is, that it breaks out of so inconsiderable an Hillock, or Eminence of Ground, that can have no more Influence in the Condensation of the Vapours, or stopping the Clouds, (which the Maintainers of this Hypothesis suppose) than the lower Lands about it have. By some Critical Observations I made with a very nice portable Barometer, I found that my House stands between 80 and 90 Feet higher than the Low-Water Mark in the River of Thames, nearest me; and that part of the River being scarce thirty Miles from the Sea, I guess, (and am more confirmed from some later Experiments I made nearer the Sea) that we cannot be much above 100 Feet above the Sea. The Spring I judge nearly level with, or but little higher than where my House stands; and the Lands from whence it immediately issues, I guess about 15 or 20 Feet higher than the Spring: and the Lands above that, of no very remarkable Height. And indeed, by actual Measure, one of the highest Hills I have met with in Essex, is but 363 Feet high; (Vid. Phil. Trans. Nᵒ. 313. p. 16.) and I guess by some very late Experiments I made, neither that, nor any other Land in Essex, to be above 400 Feet above the Sea. Now what is so inconsiderable a rise of Land to a perennial Condensation of Vapours, fit to maintain even so inconsiderable a Fountain, as what I have mentioned is? Or indeed the High-lands of the whole large County of Essex, to the maintaining of all its Fountains and Rivulets?

But I shall no farther prosecute this Argument, but refer to the late learned, curious and industrious Dr. Plot’s Tentamen Phil. de Orig. Font. in which he hath fully discussed this Matter.

As to the manner how the Waters are raised up into the Mountains and Higher Lands, an easy and natural Representation may be made of it, by putting a little Heap of Sand, Ashes, or a little Loaf of Bread, &c. in a Bason of Water; where the Sand will represent the dry Land, or an Island, and the Bason of Water the Sea about it. And as the Water in the Bason riseth to, or near the top of the Heap in it, so doth the Waters of the Sea, Lakes, &c. rise in the Hills. Which case I take to be the same with the ascent of Liquids in capillary Tubes, or between contiguous Planes, or in a Tube filled with Ashes: Of which the industrious and compleat Artificer in Air-Pumps, Mr. Hawksbee, hath given us some, not contemptible Experiments, in his Phys. Mech. Exp. pag. 139.

Among the many Causes assigned for this ascent of Liquors, there are two that bid the fairest for it, viz. the Pressure of the Atmosphere, and the Newtonian Attraction. That it is not the former, appears from the Experiments succeeding, as well, or better in Vacuo, than in the open Air, the ascent being rather swifter in Vacuo. This then being not the Cause, I shall suppose the other is; but for the Proof thereof, I shall refer to some of our late English Authors, especially some very late Experiments made before our most famous R. S. which will be so well improved by some of that illustrious Body, as to go near to put the Matter out of doubt.