FOOTNOTES:
[a] Clouds and Rain are made of Vapours raised from Water, or Moisture only. So that I utterly exclude the Notion of Dry, Terrene Exhalations, or Fumes, talked much of by most Philosophers; Fumes being really no other than the humid Parts of Bodies respectively Dry.
These Vapours are demonstratively no other than small Bubbles, or Vesiculæ detached from the Waters by the Power of the Solar, or Subterraneous Heat, or both. Of which see [Book 2. Chap. 5. Note (b).] And being lighter than the Atmosphere, are buoyed up thereby, until they become of an equal Weight therewith, in some of its Regions aloft in the Air, or nearer the Earth; in which those Vapours are formed into Clouds, Rain, Snow, Hail, Lightning, Dew, Mists, and other Meteors.
In this Formation of Meteors the grand Agent is Cold, which commonly, if not always, occupies the superior Regions of the Air; as is manifest from those Mountains which exalt their lofty Tops into the upper and middle Regions, and are always covered with Snow and Ice.
This Cold, if it approaches near the Earth, presently precipitates the Vapours, either in Dews; or if the Vapours more copiously ascend, and soon meet the Cold, they are then condensed into Misting, or else into Showers of small Rain, falling in numerous, thick, small Drops: But if those Vapours are not only copious, but also as heavy as our lower Air it self, (by means their Bladders are thick and fuller of Water,) in this Case they become visible, swim but a little Height above the Earth, and make what we call a Mist or Fog. But if they are a Degree lighter, so as to mount higher, but not any great Height, as also meet not with Cold enough to condense them, nor Wind to dissipate them, they then form an heavy, thick, dark Sky, lasting oftentimes for several Weeks without either Sun or Rain. And in this Case, I have scarce ever known it to Rain, till it hath been first Fair, and then Foul. And Mr. Clarke, (an ingenious Clergyman of Norfolk, who in his Life-time, long before me, took notice of it, and kept a Register of the Weather for thirty Years, which his learned Grandson, Dr. Samuel Clarke put into my Hands, he, I say) saith, he scarce ever observed the Rule to fail in all that Time; only he adds, If the Wind be in some of the easterly Points. But I have observed the same to happen, be the Wind where it will. And from what hath been said, the Case is easily accounted for, viz. whilst the Vapours remain in the same State, the Weather doth so too. And such Weather is generally attended with moderate Warmth, and with little or no Wind to disturb the Vapours, and an heavy Atmosphere to support them, the Barometer being commonly high then. But when the Cold approacheth, and by condensing drives the Vapours into Clouds or Drops, then is way made for the Sun-beams, till the same Vapours, being by further Condensation formed into Rain, fall down in Drops.
The Cold’s approaching the Vapours, and consequently the Alteration of such dark Weather I have beforehand perceived, by some few small Drops of Rain, Hail, or Snow, now and then falling, before any Alteration hath been in the Weather; which I take to be from the Cold meeting some of the straggling Vapours, or the uppermost of them, and condensing them into Drops, before it arrives unto, and exerts it self upon the main Body of Vapours below.
I have more largely than ordinary insisted upon this part of the Weather, partly, as being somewhat out of the way; but chiefly, because it gives Light to many other Phænomena of the Weather. Particularly we may hence discover the Original of Clouds, Rain, Hail and Snow; that they are Vapours carried aloft by the Gravity of the Air, which meeting together so as to make a Fog above, they thereby form a Cloud. If the Cold condenseth them into Drops, they then fall in Rain, if the Cold be not intense enough to freeze them: But if the Cold freezeth them in the Clouds, or in their Fall through the Air, they then become Hail or Snow.
As to Lightning, and other enkindled Vapours, I need say little in this Place, and shall therefore only observe, that they owe also their Rise to Vapours; but such Vapours as are detached from mineral Juices, or at least that are mingled with them, and are fired by Fermentation.
Another Phænomenon resolvable from what hath been said is, why a cold, is always a wet Summer, viz. because the Vapours rising plentifully then, are by the Cold soon collected into Rain. A remarkable Instance of this we had in the Summer of 1708, part of which, especially about the Solstice, was much colder than usually. On June 12, it was so cold, that my Thermometer was near the Point of hoar Frost, and in some Places I heard there was an hoar Frost; and during all the cool Weather of that Month, we had frequent and large Rains, so that the whole Month’s Rain amounted to above two Inches Depth, which is a large Quantity for Upminster, even in the wettest Months. And not only with us at Upminster, but in other Places, particularly at Zurich in Switzerland, they seem to have had as unseasonable Cold and Wet as we. Fuit hic mensis——præter modum humidus, & magno quidem vegetabilibus hominibusque damno. Multum computruit Fœnum, &c. complains the industrious and learned Dr. J. J. Scheuchzer: Of which, and other Particulars, I have given a larger Account in Phil. Trans. Nᵒ. 321.
In which Transaction I have observed farther, that about the Equinoxes we (at Upminster at least) have oftentimes more Rain than at other Seasons. The Reason of which is manifest from what hath been said, viz. in Spring, when the Earth and Waters are loosed from the brumal Constipations, the Vapours arise in great Plenty: And the like they do in Autumn, when the Summer Heats, that both dissipated them, and warmed the superior Regions, are abated; and then the Cold of the superior Regions meeting them, condenseth them into Showers, more plentifully than at other Seasons, when either the Vapours are fewer, or the Cold that is to condense them is less.
The manner how Vapours are precipitated by the Cold, or reduced into Drops, I conceive to be thus: Vapours being, as I said, no other than inflated Vesiculæ of Water; when they meet with a colder Air than what is contained in them, the contained Air is reduced into a less Space, and the watery Shell or Case rendered thicker by that means, so as to become heavier than the Air, by which they are buoyed up, and consequently must needs fall down. Also many of those thickned Vesiculæ run into one, and so form Drops, greater or smaller, according to the Quantity of Vapours collected together.
As to the Rain of different Places, I have in some of our Transactions assigned the Quantities; particularly in the last cited Transaction, I have assigned these, viz. the Depth of the Rain one Year with another, in English Measure, if it was to stagnate on the Earth, would amount unto, at Townely in Lancashire, 42½ Inches; at Upminster in Essex 19¼ Inches; at Zurich in Switzerland 32¼ Inches; at Pisa in Italy 43¼ Inches; at Paris in France 19 Inches; and at Lisle in Flanders 24 Inches.
It would be endless to reckon up the bloody and other prodigious Rains taken notice of by Historians, and other Authors, as præternatural and ominous Accidents; but, if strictly pried into, will be found owing to natural Causes: Of which, for the Reader’s Satisfaction, I will give an Instance or two. A bloody Rain was imagined to have fallen in France, which put the Country People into so great a Fright, that they left their Work in the Fields, and in great haste flew to the Neighbouring Houses. Peirise (then in the Neighbourhood) strictly enquiring into the Cause, found it to be only red Drops coming from a sort of Butterfly that flew about in great Numbers at that Time, as he concluded from seeing such red Drops come from them; and because these Drops were laid, Non supra ædificia, non in devexis lapidum superficiebus, uti debuerat contingere, si è cœlo sanguine pluisset; sed in subcavis potius & in foraminibus.——Accessit, quòd parietes iis tingebantur, non qui in mediis oppidis, sed qui agrorum vicini erant, neque secundum partes elatiores, sed ad mediocrem solùm altitudinem, quantam volitare Papiliones solent. Gassend in vit. Peiresk. L. 2. p. 156.
So Dr. Merret saith also, Pluvia Sanguinis quàm certissimè constat esse tantùm Insectorum excrementa: Pluvia Tritici quàm nihil aliud esse quàm Hederæ bacciferæ grana à Sturnis devorata excretaque comparanti liquidissimè patet. Pinax rerum, &c. p. 220.
The curious Worm tells of the raining of Brimstone, An. 1646. Maii 16. Hic Hafniæ cùm ingenti pluviâ tota urbs, omnesque ita inundarentur plateæ, ut gressus hominum impediret, Sulphureoque odore aërem inficeret, dilapsis aliquantulum aquis, quibusdam in locis colligere licuit Sulphureum pulverem, cujus portionem servo, colore, odore, & aliis verum Sulphur ferentem. Mus. Worm. L. 1. c. 11. Sect. 1.
Together with the Rain we might take notice of other Meteors, particularly Snow; which although an irksome Guest, yet hath its great Uses, if all be true that the famous T. Bartholin saith of it, who wrote a Book de Nivis usu Medico. In which he shews of what great Use Snow is in fructifying the Earth, preserving from the Plague, curing Fevers, Colicks, Head-Aches, Tooth-Aches, Sore Eyes, Pleurisies, (for which Use he saith his Country-Women of Denmark keep Snow-Water gathered in March), also in prolonging Life, (of which he instanceth in the Alpine Inhabitants, that live to a great Age,) and preserving dead Bodies; Instances of which he gives in Persons buried under the Snow in passing the Alps, which are found uncorrupted in the Summer, when the Snow is melted; which sad Spectacle he himself was an Eye-Witness of. And at Spitzberg in Greenland, dead Bodies remain entire and uncorrupted for thirty Years. And lastly, concerning such as are so preserv’d when slain, he saith they remain in the same Posture and Figure: Of which he gives this odd Example, Visum id extra urbem nostram [Hafniam] quum, 11 Feb. 1659. oppugnantes hostes repellerentur, magnâque strage occumberent; alii enim rigidi iratum vultum ostendebant, alii oculos elatos, alii ore diducto ringentes, alii brachiis extensis Gladium minari, alii alio situ prostrati jacebant. Barthol. de usu Niv. c. 12.
But although Snow be attended with the Effects here named, and others specified by the learned Bartholin; yet this is not to be attributed to any peculiar Virtue in the Snow, but some other Cause. Thus when it is said to fructify the Earth, it doth so by guarding the Corn or other Vegetables against the intenser cold of the Air, especially the cold piercing Winds; which the Husbandmen observe to be the most injurious to their Corn of all Weathers. So for Conserving dead Bodies, it doth it by constipating such Bodies, and preventing all such Fermentations or internal Conflicts of their Particles, as would produce Corruption.
Such an Example as the preceding is said to have happened some Years ago at Paris, in digging in a Cellar for supposed hidden Treasure; in which, after digging some Hours, the Maid going to call her Master, found them all in their digging Postures, but dead. This being noised abroad, brought in not only the People, but Magistrates also, who found them accordingly; Ille qui ligone terram effoderat, & socius qui palâ effossam terram removerat, ambo pedibus stabant, quasi sua quisque operâ affixus incubuisset; uxor unius quasi ab opere defessa in scamno, solicito quodam vultu, sedebat, inclinato in palmam manûs genibus innitentis capite; puerulus laxatis braccis in margine excavatæ foveæ defixis in terram oculis alvum exonerabat; omnes in naturali situ, carneæ tanquam statuæ rigidi, apertis oculis & vultu vitam quasi respirante, exanimes stabant. Dr. Bern. Connor, Dissert. Med. Phys. p. 15.
The Doctor attributes all this to Cold; but I scarce think there could be Cold enough to do all this at Paris, and in a Cellar too. Bur his following Stories are not improbable, of Men and Cattle killed with Cold, that remained in the very same Posture in which they died; of which he gives, from a Spanish Captain, this Instance, that happened two Years before, of a Soldier who unfortunately straggled from his Company that were foraging, and was killed with the Cold, but was thought to have fallen into the Enemies Hands. But soon after their return to their Quarters, they saw their Comrade returning, sitting on Horseback, and coming to congratulate him, found him dead, and that he had been brought thither in the same Posture on Horseback, notwithstanding the jolting of the Horse. Ibid. p. 18.
[] Of this Opinion was my late most ingenious and learned Friend, Mr. Ray, whose Reasons see in his Physico-Theolog. Discourses, Disc. 2. ch. 2. p. 89, &c. So also my no less learned and ingenious Friends, Dr. Halley, and the late Dr. Hook, many of the French Vertuoso’s also, and divers other very considerable Men before them, too many to be specified here.
[c] An Polycletum quidem admirabimur propter partium Statuæ—convenientiam ac proportionem? Naturam autem non modò non laudabimus, sed omni etiam arte privabimus, quæ partium proportionem non solùm extrinsecus more Statuariorum, sed in profundo etiam servavit? Nonne & Polycletus ipse Naturæ est imitator, in quibus saltem eam potuit imitari? Potuit autem in solis externis partibus in quibus artem consideravit. With much more to the like Purpose, Galen. de Us. Part. l. 17. c. 1.
CHAP. IV.
Of Light.
Thus much for the first Thing ministring to the Terraqueous Globe, the Atmosphere and its Meteors; the next Appendage is Light.[a] Concerning which I have in my Survey of the Heavens[] shewed what admirable Contrivances the infinitely wise Creator hath for the affording this noble, glorious and comfortable Benefit to other Globes, as well as ours; the Provision he hath made by Moons, as well as by the Sun, for the Communication of it.
And now let us briefly consider the great Necessity and Use thereof to all our Animal World. And this we shall find to be little less than the very Life and Pleasure of all those Creatures. For what Benefit would Life be of, what Pleasure, what Comfort would it be for us to live in perpetual Darkness? How could we provide ourselves with Food and Necessaries? How could we go about the least Business, correspond with one another, or be of any Use in the World, or any Creatures be the same to us, without Light, and those admirable Organs of the Body, which the great Creator hath adapted to the Perception of that great Benefit?
But now by the help of this admirable, this first-made[c], because most necessary, Creature of God, by this, I say, all the Animal World is enabled to go here and there, as their Occasions call; they can transact their Business by Day, and refresh and recruit themselves by Night, with Rest and Sleep. They can with Admiration and Pleasure, behold the glorious Works of God; they can view the Glories of the Heavens, and see the Beauties of the flowry Fields, the gay Attire of the feathered Tribe, the exquisite Garniture of many Quadrupeds, Insects, and other Creatures; they can take in the delightsome Landskips of divers Countries and Places; they can with Admiration see the great Creator’s wonderful Art and Contrivance in the Parts of Animals and Vegetables: And in a word, behold the Harmony of this lower World, and of the Globes above, and survey God’s exquisite Workmanship in every Creature.
To all which I might add the Improvements which the Sagacity of Men hath made of this noble Creature of God, by the Refractions and Reflections of Glasses. But it would be endless to enumerate all its particular Uses and Benefits to our World.
But before I leave this Point, there are two Things concerning Light, which will deserve an especial Remark; and that is, its swift and almost instantaneous Motion, and its vast Extension.
1. It is a very great Act of the Providence of God, that so great a Benefit as Light is, is not long in its Passage from Place to Place. For was the Motion thereof no swifter than the Motion of the swiftest Bodies on Earth, such as of a Bullet out of a great Gun, or even of a Sound[d] (which is the swiftest Motion we have next Light), in this Case Light would take up, in its Progress from the Sun to us above thirty two Years at the rate of the first, and above seventeen Years at the rate of the latter Motion.
The Inconveniencies of which would be, its Energy and Vigour would be greatly cooled and abated; its Rays would be less penetrant; and Darkness would with greater Difficulty and much Sluggishness, be dissipated, especially by the fainter Lights of our sublunary, luminous Bodies. But passing with such prodigious Velocity, with nearly the instantaneous Swiftness of almost Two hundred thousand English Miles in one Second of Time,[e] or (which is the same Thing) being but about seven or eight Minutes of an Hour in coming from the Sun to us, therefore with all Security and Speed, we receive the kindly Effects and Influences of that noble and useful Creature of God.
2. Another Thing of great Consideration about Light is, its vast Expansion, it’s almost incomprehensible, and inconceivable Extension, which as a late ingenious Author[f] saith, “Is as boundless and unlimited as the Universe it self, or the Expansum of all material Beings: The vastness of which is so great, that it exceeds the Comprehensions of Man’s Understanding. Insomuch that very many have asserted it absolutely infinite, and without any Limits or Bounds.”
And that this noble Creature of God is of this Extent,[g] is manifest from our seeing some of the farthest distant Objects, the heavenly Bodies, some with our naked Eye, some with the help of Optical Instruments, and others in all Probability farther and farther, with better and better Instruments: And had we Instruments of Power equivalent to the Extent of Light, the luminous Bodies of the utmost Parts of the Universe, would for the same Reason be visible too.
Now as Light is of greatest Use to impower us to see Objects at all, so the Extension thereof is no less useful to enable us to see Objects afar off. By which means we are afforded a Ken of those many glorious Works of the infinite Creator, visible in the Heavens, and can improve them to some of the noblest Sciences, and most excellent Uses of our own Globe.