XXIV. Physical and meteorological observations, conjectures, and suppositions I « ? » ] XXIV. Phyjical and Meteorological Obferva- tionsyConjeElure$i and Suppofitiom̂ by Ben­ jamin FrankKn̂ Ĵ Z/. B land * Read June 3, r “j ' ^ H E particles of air are kept at a X diftance from each other by their mutual repulfion. i -r : • (IOj ’’ ( c-i : !: Every three particles mutually and equally re­ pelling each other, muft form an equilateral tri­ angle. AH the particles of air gravitate towards the earth, which gravitation comprefles them, and fhortens the fides of the triangles, btherwife their mutual re- pellency would force them to greater diftances from each other. j, j§,4̂ ! Whatever particles of other matter (not endued with that repellency) are fupported in air, muft ad­ here to the particles of air, and be ftipported by them j for in the vacancies there is nothing they can reft on. Air and water mutually attrad each other. Hence water will diflolve in air, as fait in water. • T h e fpecific gravity of matter is not altered by di­ viding the matter, though the fuperficies be increafed. Sixteen leaden bullets, of an ounce each, weigh as much in water, as one of a pound, whofe fuper- ncies is lefs. it ? j j a d in g the preceding paper in the Society, it was re­ collected that this paper, fimilar in fome particulars, had been communicated to the Society about nine years before, though not till now printed.- & Therefore D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 t **3 ] Therefore the fupporting of fait in water is not owing to its fuperficies being encreafed. * ; 1 fc a A lump of fait# though laid at red! at the bottom of a veflel of water,, will diffolve therein, and its parts move every way till equally diffufed in the watery therefore there is a mutual attraction between water and fa it Every particle of water aflumes as many o f fait as can adhere to It 5 when more is added, it precipitates, and will not remain fufpended. W ater,, in the fame manner, will diffolve in air, every particle of air affuming one or more particles of water 5 when too much is added, it precipitates • in-.rain.: ■ v 3|* W m m t - ' . - . W thferg contiguity between \ the particles of air as of water, the folution of wa­ ter m air k not carried on without a motion of the ^ r , fb as to caufe a firefly acceflion of dry particles. ’7, of a fluid, having more of what It diffolves, will communicate to other parts that have lefs. Thus very ifalt Water Coming fin contadl with frefh, communicates its faltnM till all is equal, and the fooner if there is a little motion of the water. f ^ ven rear^ Ŵ 1 difiblve, or mix with. air* A itroke of a horfe’s hoof on the ground in a hot oufty TOad, will raife a Cloud o f duft,,that ihall, if there be alight breeze, expand every way till perhaps, near as big as a common h o u fe.t Tis mot m me- i chamcal motion communicated to the particles of duff by the hoof; that they % fb far, nor;v b y ! the wind t at t n y fpiead fb wide;* f But the air near th b n ro b n d ,, jieated by the hot duflrffruck into it, is rariflecf ! ami rifev and in riling mixes with thecoolcr and communicates of its buff to k, and it is at length fo diffufed * D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ . 8 4 ] diffufed as to become invifible. Quantities of duft are thus carried up in dry feafons. Showers wafh it from the air and bring it down again. For water attra&ing it ftronger, it quits the air and adheres to .the water. Air fuffering continual changes in the degrees o f its heat, from various caufes and circumftances, and confequently changes in its fpecific gravity, raufl therefore be in continual motion* A fmall quantity of fire mixed with water (or de­ gree o f heat therein) fo weakens the cohefion of its particles, that thofe on the furface eafily quit it, and adhere to the particles of air. .A greater degree of heat is required to break the cohefion-between water and air. Air moderately heated will fupport a greater quan­ tity of water invifibly than cold air j for its particles being by heat repelled to a greater diftance from each other, thereby more eafily keep the particles o f water, that are annexed to them, from running into cohefions that would obftruft, refract, or reflect the light. Hence, when we breathe in warm air, though the lame quantity o f moifture may be taken up from the lungs as when we breathe in cold air, yet that moifture is not fo vifible. snifii Water being extremely heated, to the degree of boiling, its' particles, in quitting it, fo repel each other, as to take up vaftly more fpace than before, and by that repellency fupport themfelves, expelling the air from the fpace they occupy. T hat degree o f heat being leflened, they again mutually attract, and having no air-particles mixed, to adhere to, by 2 which D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ 3 which they m ightbe fupported and. kept at a dih fta®ee, they instantly All; coalesce, and become w%. ter again. c i T he water commonly diffufed in our atmofpher.e never receives fuch a degree o f heat from the Ain, pr othei’ caufe, as water, has when boiling } jt is not, therefore, fupported by fuch heat, but by adhering to air. ® Water being diflolved in, and adhering to air, that air will not readily take up oil, because of the natural repeliency between water and oil. Hence cold oils evaporate but flowly, the air having generally a quantity of diffolved water. ; Oil being heated extreamly, the air that approaches its furface will be alfo heated extremely} the water then, quitting it, it will attract and carry off oil, which can now adhere to it. Hence the auick eva­ poration of oil heated to a great degree., fc Qil being diffoived in air, the particles to which it adheres will not take up water. .Hence the fuffocating nature o f air impregnated with burnt greafe, as from fnuffs of candles, and the like. A certain quantity of moifture (hould be every moment difeharged and taken away from the lungs. Air that has overloaded, and for that reafon, can take no more, fo will not anfwer the end. Greafy air refufes to tpuch it. In both cafes fuffocation for want of the di (charge.; " , / ' r . “ ?! Air will attract, and fupport many other fub- ftances. l->-t ' ,r * * ip A particle of air. loaded whh adhering water Hor apy other matter, % ' t j ^ q e r ^ bqfqre, defend. ' . . c/i.-.,ir V ol. LV. B b T he D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ i « 6 ] The atmofphefe fuppofed at reft, a loaded de- fcending particle muft adt with a force on the par­ ticles it pafifes between, or meets with, fufficient to overcome in fome degree their mutual repellency, and pufh them nearer to each other. a Thus, fuppofing the particles o o o A B C D, and the others near f o bo co go them, to be at the diftance o do o caufed by their mutual repel- o o o o lency (confined by their com- E mon gravity) if A would de- fcend to E, it muff pafs between B and C. When it conies between B and C, it will be nearer to them than before, and muft either have pufiled them nearer to F and G, contrary to their mutual repellency, or pafs through by a force exceeding its repellency with them. It then approaches D, and, to move it out of the way, muft adt on it with a force fufficient to overcome its repellency with the two next lower par­ ticles, by which it is kept in its prefent fituation. Every particle o f air, therefore, will bear any load inferior to the forcQjjf- thefe repulfions. Hence the fupport of fogs, mifts, clouds. Very warm air, clear, though Supporting a very great quantity of moifture, will grow turbid and cloudy on the mixture of a colder a i r : as foggy tur­ bid air will grow clear by warming. Thus the fun ffiining on a morning fog, diffipates it. Clouds are feen to wafte in a funfiiiny day. But cold condenfes and renders vifible the vapour. A tankard, or decanter, filled with cold water, will condenfe the moifture o f warm clear air, on its outfide, where it becomes vifible as dew, coalefces into drops, defcends in little ftreams. 4 T he D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ lS 7 ] T he fun heats the air o f our atmofphere moil near the furface of the earth -} for there, beiides the diredl rays, there are many refle&ions. Moreover, the earth itfelf being heated, communicates of its heat to the neighbouring air; The higher regions having only the direct rays o f the fun palling through them, are comparatively very cold. Hence the cold air on the tops of mountains, and fnow on fome of them all the year, even in the torrid zone. Hence hail in fummer. If the atmofphere were, all of it (both above and below) always of the fame temper as to cold or heat, then the upper air would always be rarer than the lower, becaufe the prelfure on it is lefs j , confequently lighter, and therefore would keep its place. But the upper air may be more condenfed by cold, than the lower air by preifure. T h e lower more expanded by heat, than the upper for want of pref- fure. In fiich cafe, the upper air will become the heavier, the lower the lighter. The lower region of air being heated and expand­ ed, heaves up and fupports, for fome time, the colder heavier air above, and will continue to fupport it while the equilibrium is kept. Thus water is Sup­ ported in an inverted open glafs, while the equili­ brium is maintained by the equal preflure upwards o f the air below j but the equilibrium by any means breaking, the water defcends on the heavier fide, and the air rifes into its place. The lifted cold heavy arr over a heated country, becoming by any means unequally fupported, or un­ equal in its weights, the heavieft part defcends firft, and the reft follows impetuoufly. Hence gufts after heats, and hurricanes in hot climates. Hence the B b 2 air D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 air of gpfts, and hurricanes cold, though in hot climes and feafons; it coming from above. T he cold air defending from above, as it pene­ trates our warm region full o f watry particles, con- denfes them, renders them vifible, forms a cloud thick and dark, overcafting fometimes at once, large and extenfive; fometimes, when feen at a diftance, fmall at firft, gradually increafingj the cold edge, or furface, of the cloud, condenfing the vapours next it, which form fmaller clouds, that join it, encreafe its bulk, it defcends with the wind and its acquired weight, draws nearer the earth, grows denfer with continual additions of water, and difcharges heavy (bowers. Small black clouds thus appearing in a clear fky, in hot climates, portend florins, and warn feamen to hand their fails. T he earth turning on its axis in about 24 hours, the equatorial parts mufl move about 15 miles in each minute. In northern and fouthern latitudes this motion is gradually lefs to the poles, and there no­ thing. If there was a general calm over the face of the globe, it muft be by the air’s, moving in every part, as faft as the earth, or fea, it covers. He that fails, or rides, has infenfibly the fame degree of motion, as the fhip, or coach, with which he is connected*' If the fhip firikes the fhore, or the coach flops fuddenly, the motion continuing in the man, he is thrown forward. If a man were to jum p from ’the land into a fwift failing fhip, he would be thrown backward (or towards the flern) not having at firft the motion of the fhip. [ 188 ] He D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ i89 ] He that travels, by fea or land, towards the equi­ noctial, gradually acquires motion j from it, lofes. But if a man were taken up from latitude 40 (where fuppofe the earth’s furface to move 12 miles p e r minute) and immediately fet down at the equi­ noctial, without changing the motion he had, his heels would be ftruck up, he would fall weftward. I f taken up from the equinoctial, and fee down in latitude 40, he would fall eaftward. T he air under the equator, and between the tro­ pics, being conftantly heated and rarified by the fun, rifes. Its place is fupplied by air from northern and fouthern latitudes, which coming from parts where the earth and air had lefs motion, and not fud- denly acquiring the quicker motion of the equatorial earth, appears an eaft wind blo wing wed ward, the earth moving from weft to eaft, and flipping under theair. Thus, when we ride in a calm, it feems a wind againft us. If we ride with the wind* and fafter, even that will feem a {mall wind againft us. T he air ratified between the tropics, and rifing, m u d flow in the higher region north and fouth. Be­ fore it fofe, it had acquired the greateft motion the earth’s rotation could give it. It retains fome de­ gree of this motion, and defending in higher lati­ tudes, where the earth’s motion is lefs, will appear a wefterly wind, yet tending towards the equatorial parts, to fupply the vacancy occafioned by the air of the lower regions flowing thitherwards. Hence our general cold winds are about northweft, our fummer cold gufts the fame. The D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ r 9° ] The air in fultry weather, though not cloudy, has a kind of hazinefs in it, which makes obje&s at a diftance appear dull and indiftind. This hazinefs is occalioned by the great quantity of moifture equally difFufed in that air. When, by the cold wind blow­ ing down among it, it is condenfed into clouds, and falls in rain, the air becomes purer and clearer. Hence, after gufts, diftant objeds appear diftind, their figures fharply terminated. Extreme cold winds congeal the furface o f the earth, by carrying off its fire. W arm winds after­ wards blowing over thkt frozen furface will be chilled by it. Could that frozen furface be turned under, and a warmer turned up from beneath it, thofe warm winds would not be chilled fom ucb. T he furface of the earth is alfo fometimes much heated by the fun j and fuch heated furface not being changed, heats the air that moves over it. Seas, lakes, and great bodies of water, agitated by the winds, continually change furfacesj the cold furface in winter is turned under, by the rolling of the waves, and a warmer turned up j in fummer, the warm is turned under, and colder turned up. Hence the more equal temper of fea-water, and the air over it. Hence in winter, winds from the fea feem warm, winds from the land cold. In fum­ mer the contrary.?', Therefore the lakes north-weft of us *, as they are not fo much frozen, nor fo apt to freeze as the earth, rather moderate than increafe the coldnefs of our winter winds. The air over the fea being warmer, and therefore lighter in winter than the air over the frozen land, * In Penfilvania. may D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ J 9 * ] may be another caufe of our general north-weft winds, which blow off to fea at right angles from our North American coaft? the warm light fea air riling, the heavy cold land air prefling into it* place. Heavy fluids defcending frequently form eddies, or whirlpools, as is feen in a funnel, where the water acquires a circular motion receding every way from a centre, and leaving a vacancy in the middle, greateft above, and leffening downwards, like a fpeaking trumpet, its big end upwards. Air defcending, or afcending, may form the fame kind of eddies, or whirlings, the parts of air ac­ quiring a circular motion, and receding from the middle o f the circle by a centrifugal force, and leav­ ing there a vacancy, if defeending, greateft above, and •leffening downwards; if afcending, greateft be­ low, and leffening upwards, like a fpeaking trumpet, ftanding its big end on the ground. When the air defcends with violence in fome places, it may rife with equal violence in others, and form both kinds of whirlwinds. T he air in its whirling motion receding every way from the centre, or axis, of the trumpet, leaves there a vacuum, which cannot be filled through the tides, the whirling air as an arch preventing; it muft then prefs in at the open ends. The greateft prefiure inwards muft be at the lower end, the greateft weight of the furrounding atmo- fphere being there. The air entering rifes within, and carries up duft, leaves, and even heavier bodies that happen in its way, as the eddy or whirlpool paffes over land. I f D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1 [ *92 0 I f it paffes over water, the weight of the furround- ing atmofphere forces up the water into the vacuity, part of which, by degrees jo in s with the whirling air, and adding weight, and receiving accelerated motion, recedes ftill farther from the centre, or axis, o f the trump, as the preflure leflens, and at laft, as the trump widens, is broken into fmali particles, and fo united with air, as to be fupported by it, and be­ come black clouds at the top of the trump. Thus thefe eddies may be whirlwinds at land, waterfpouts at fea. A body of water To raifed may be fuddenfy let fall, when the motion, &c. has not ftrength to fupport it, or the whirling arch is broken fo as to let in the air 5 falling in the fea, it is harmlefs, unlefs {hips happen under it. But if in the pro- grefhve motion of the whirl it has moved from the fea over the land, and there breaks,, fudden, violent, and mifchievous torrentB are the conference* D ow nl oa de d fr om h tt ps :/ /r oy al so ci et yp ub li sh in g. or g/ o n 05 A pr il 2 02 1