« ZurückWeiter »
electrified, joins with the natural repulsion of wards the mountains and towards each other. the air, to force its particles to a greater dis- If the air was not much loaded, it only falls tance, whereby the triangles are dilated, and in dews on the mountain tops and sides, forms the air rises, carrying up with it the water springs, and descends to the vales in rivulets,
20. If the particles of water bring with which, united, inake larger streams and rivers. them portions of both sorts of fire, the repul- If much loaded, the electrical fire is at once sion of the particles of air is still more strength- taken from the whole cloud; and, in leaving it, ened and increased, and the triangles farther flashes brightly and cracks loudly; the partienlarged.
cles instantly coalescing for want of that fire, 21. One particle of air may be surrounded and falling in a heavy shower. by twelve particles of water of equal size with 30. When a ridge of mountains thus dams itself, all in contact with it; and by more ad- the clouds, and draws the electrical fire from ded to those
the cloud first approaching it; that which 22. Particles of air, thus loaded would be next follows, when it comes near the first drawn nearer together by the mutual attrac- cloud, now deprived of its fre, flashes into it, tion of the particles of water, did not the fire, and begins to deposite its own water; the common or electrical, assist their repulsion. first cloud again flashing into the mountains;
23. If air, thus loaded, be compressed by the third approaching cloud, and all succeedadverse winds, or by being driven against ing ones, acting in the same manner as far mountains, &c., or condensed by taking away back as they extend, which may be over many the fire that assisted it in expanding; the tri- hundred miles of country. angles contract, the air with its water will de 31. Hence the continual storms of rain, scend asa dew; or, if the water surrounding thunder, and lightning on the east side of the one particle of air comes in contact with the Andes, which running north and south, and water surrounding another, they coalesce and being vastly high, intercept all the clouds form a drop, and we have rain.
brought against them from the Atlantic ocean 24. The sun supplies (or seems to supply) | by the trade winds, and oblige them to depocommon fire to vapours, whether raised from site their waters, by which the vast rivers earth or sea.
Amazons, La Plata, and Oroonoko are form25. Those vapours, which have both common ed, which return the water into the same sea and electrical fire in them, are better support- after having fertilized a country of very great ed than those which have only common fire in extent. them; for when vapours rise into the coldest 32. If a country be plain, having no moun. region above the earth, the cold will not di- tains to intercept the electrified clouds, yet it minish the electrical fire, if it doth the com- is not without means to make them deposite
their water. For if an electrified cloud, com26. Hence clouds, formed by vapours raised ing from the sea, meets in the air a cloud raisfrom fresh waters within land, from growing ed from the land, and therefore not electrified, vegetables, moist earth, &c. more speedily the first will flash its fire into the latter, and and easily deposite their water, having but thereby both clouds shall be made suddenly to little electrical fire to repel and keep the par- deposite water. ticles separate. So that the greatest part of 33. The electrified particles of the first the water raised from the land, is let fall on cloud close when they lose their fire; the parthe land again ; and winds blowing from the ticles of the other clouds close in receiving it: land to the sea are dry; there being little use in both, they have thereby an opportunity of for rain on the sea, and to rob the land of its coalescing into drops.— The concussion, or moisture, in order to rain on the sea, would jerk given to the air, contributes also to shake not appear reasonable.
down the water, not only from those two 27. But clouds, formed by vapours raised clouds, but from others near them. Hence from the sea, having both fires, and particu- the sudden fall of rain immediately after flashlarly a great quantity of the electrical, support es of lightning. their water strongly, raise it high, and being 34. To show this by an easy experiment: moved by winds, may bring it over the mid- take two round pieces of pasteboard two inchdle of the broadest continent from the middle es diameter; from the centre circumference of the widest ocean.
of each of them suspend by fine silk threads 28. How these ocean clouds, so strongly eighteen inches long, seven small balls of supporting their water are made to deposite it wood, or seven peas equal in goodness : 80 on the land where it is wanted is next to be will the balls appending to each pasteboard, considered.
form equal equilateral triangles, one ball being 29. If they are driven by winds against in the centre, and six at equal distances from mountains, those mountains being less elec- that, and from each other; and thus they retrified attract them, and on contact take away present particles of air. Dip both sets in watheir electrical fire (and being cold, the com- ter, and some adhering to each ball, they will mon fire also ;) hence the particles close to representair loaded. Dexterously electrify one
set, and its balls will repel each other to a When the air, with its vapours raised from greater distance, enlarging the triangles. the ocean between the tropics, comes to de. Could the water supported by seven balls scend in the polar regions and to be in contact come into contact, it would form a drop or with the vapours arising there, the electrical drops so heavy as to break the cohesion it had fire they brought begins to be communicated, with the balls, and so fall
. Let the two sets and is seen in clear nights, being first visible then represent two clouds, the one a sea cloud where it is first in motion, that is, where the electrified, the other a land cloud. Bring contact begins, or in the most northern part; them within the sphere of attraction, and they from thence the streams of light seem to will draw towards each other, and you will shoot southerly, even up to the zenith of northsee the separated balls close thus; the first ern countries. But though the light seems electrified ball that comes near an unelectri- to shoot from the north southerly, the pro fied ball by attraction joins it, and gives it gress of the fire is really from the south northfire; instantly they separate, and each flies to erly, its motion beginning in the north, being another ball of its own party, one to give, the the reason that it is there seen first. other to receive fire; and so it proceeds For the electrical fire is never visible but through both sets, but so quick as to be in a when in motion, and leaping from body to manner instantaneous. In the cohesion they body, or from particle to particle through the shake off and drop their water which repre- air. When it passes through dense bodies it sents rain.
is unseen. When a wire makes part of the 35. Thus when sea and land clouds would circle, in the explosion of the electrical phial, pass at two great a distance for the flash, they the fire, though in great quantity, passes in are attracted towards each other till within the wire invisibly; but in passing along a that distance; for the sphere of electrical at- chain, it becomes visible as it leaps from link traction is far beyond the distance of flashing. to link. In passing along leaf gilding it is
36. When a great number of clouds from visible: for the leaf-gold is full of pores; hold the sea meet a number of clouds raised from a leaf to the light and it appears like a net, the land, the electrical flashes appear to and the fire is seen in it leaping over the vastrike in different parts; and as the clouds cancies. And as when a long canal filled are jostled and mixed by the winds, or brought with still water is opened at one end, in order near by the electrical attraction, they conti- to be discharged, the motion of the water benue to give and receive flash after flash, till the gins first near the opened end, and proceeds electrical fire is equally dissolved.
towards the close end, though the water it37. When the gun-barrel, in electrical self moves from the close towards the opened experiments) has but little electrical fire in end : so the electrical fire discharged into the it, you must approach it very near with your polar regions, perhaps from a thousand knuckle before you can draw a spark. Give leagues length of vapourised air, appears first it more fire, and it will give a spark at a where it is first in motion, i. e. in the most greater distance. Two gun-barrels united, northern part, and the appearance proceeds and as highly electrified, will give a spark at southward, though the fire really moves northa still greater distance. But if two gun-bar-ward. This is supposed to account for the aurels electrified will strike at two inches dis. rora borealis. tance, and make a loud snap, to what a great 41. When there is great heat on the land, distance may 10,000 acres of electrified cloud in a particular region (the sun having shone strike and give its fire, and how loud must be on it perhaps several days, while the surroundthat crack?
ing countries have been screened by clouds) 38. It is a common thing to see clouds at the lower air is rarified and rises, the cooler different heights passing different ways, denser air above descends; the clouds in that which shows different currents of air one un- air meet from all sides, and join over the heatder the other. As the air between the tropics ed place; and if some are electrified, others is rarified by the sun, it rises, the denser north-not, lightning and thunder succeed, and showern and southern air pressing into its place. ers fall
. Hence thunder-gusts after heats, and The air so rarified and forced up, passes north- cool air after gusts; the water and the clouds ward and southward, and must descend in the that bring it, coming from a higher and therepolar regions, if it has no opportunity before, fore a cooler region. that the circulation may be carried on.
42. An electrical spark, drawn from an ir39. As currents of air, with the clouds regular body at some distance is scarcely ever therein, pass different ways, it is easy to con- strait, but shows crooked and waving in the ceive how the clouds, passing over each other, air. So do the flashes of lightning ; the clouds may attract each other, and so come near being very irregular bodies. enough for the electrical stroke. And also 43. As electrified clouds pass over a counhow electrical clouds may be carried within try, high hills and high trees, lofty towers, land very far from the sea, before they have an spires, masts of ships, chimneys, &c., as 80 opportunity to strike.
many prominences and points, draw the elec
trical fire, and the whole cloud discharges nor altogether from agitated fire in the methere.
tals.-For as whatever body can insinuate 44. Dangerous, therefore, is it to take shel- itself between the particles of metal, and overter under a tree, during a thunder-gust. It come the attraction by which they cohere (as has been fatal to many, both men and beasts. sundry menstrua can) will make the solid be
45. It is safer to be in the open field for come a fluid, as well as fire, yet without heatanother reason. When the clothes are wet, ing it: so the electrical fire, or lightning, if a flash in its way to the ground should strike creating a violent repulsion between the paryour head, it may run in the water over the ticles of the metal it passes through, the metal surface of your body; whereas, if your clothes is fused., were dry, it would go through the body, 54. If you would, by a violent fire, melt off because the blood and other humours, con- the end of a nail, which is half driven into a taining so much water, are more ready con- door, the heat given the whole nail, before a ductors.
part would melt, must burn the board it sticks Hence a wet rat cannot be killed by the ex- in; and the melted part would burn the floor ploding electrical bottle, when a dry rat may.* it dropped on. But if a sword can be melted
46. Common fire is in all bodies, more or in the scabbard, and money in a man's pocket less, as well as electrical fire. Perhaps they by lightning, without burning either, it must may be different modifications of the same be a cold fusion.* element; or they may be different elements. 55. Lightning rends some bodies. The The latter is by some suspected.
electrical spark will strike a hole through a 47. If they are different things, yet they quire of strong paper. may and do subsist together in the sarne body. 56. If the source of lightning, assigned in
48. When electrical fire strikes through this paper be the true one, there should be a body, it acts upon the common fire contain- little thunder heard at sea from land. And ed in it, and puts that fire in motion; and if accordingly, some old sea-captains, of whom there be a sufficient quantity of each kind of inquiry has been made, do affirm, that the tire, the body will be inflamed.
fact agrees perfectly with the hypothesis; for 49. When the quantity of common fire in that in crossing the great ocean, they seldom the body is small, the quantity of the electri- meet with thunder till they come into soundcal fire (or the electrical stroke) should be ings; and that the islands far from the congreater: if the quantity of common fire be tinent have very little of it. And a curious great, less electrical fire suffices to produce observer, who lived thirteen years at Bermuthe effect.
das, says, there was less thunder there in that 50. Thus spirits must be heated before we whole time than he has sometimes heard in a can fire them by the electrical spark. If month at Carolina. they are much heated, a small spark will do; if not, the spark must be greater. 51. Till lately we could only fire warm va
To Peter Collinson, London. pours: but now we can burn hard dry rosin. Introductory Letter to some additional Papers. And when we can procure greater electrical
PHILADELPHIA, July 29, 1750. sparks, we may be able to fire not only un As you first put us on electrical experiments, warmed spirits, as lightning does, but even by sending, to our Library Company a tube, wood, by giving sufficient agitation to the with directions how to use it; and as our hocommon fire contained in it, as friction we nourable proprietary enabled us to carry those know will do.
experiments to a greater height, by his gene52. Sulphureous and inflammable vapours, rous present of a complete electrical apparaarising from the earth, are easily kindled by tus; it is fit that both should know, from time lightning. Besides what arise from the earth, to time, what progress we make. It was in such vapours are sent out by stacks of moist this view I wrote and sent you my former hay, corn, or other vegetables, which heat and papers on this subject, desiring, that as I had reek. Wood, rotting in old trees or buildings, not the honour of a direct correspondence does the same. Such are therefore easily with that bountiful benefactor to our library, and often fired.
they might be communicated to him through 53. Metals are often melted by lightning, your hands. In the same view I write and though perhaps not from heat in the lightning, send you this additional paper. If it happens
to bring you nothing new, (which may well be, * This was tried with a bottle, containing about a considering the number of ingenious men in quart. It is since thought that one of the large glass jars, mentioned in these papers, might havekilled him, * These facts, though related in several accounts, are though wet.
now doubted ; since it has been observed that the parts We have since fired spirits without heating them, of a bell-wire which fell on the floor, being broken and
A little, poured into the partly melted by lightning, did actually burn into the palm of the hand, will be warmed sufficiently by the boards. (See Philosophical Transactions, vol. li. part hand, if the spirit be well rectified. Ether takes fire i.) And Mr. Kinnersley has found that a fine iron wire most readily
melted by electricity, has had the same effect. VOL II....2 K
when the weather is warm.
but we may
Europe, continually engaged in the same re 7. But in common matter there is (genersearches) at least it will show, that the in- ally) as much of the electrical as it will construments put into our hands are not neglected; tain within its substance. If more is added, and that if no valuable discoveries are made it lies without upon the surface, and forms by us, whatever the cause may be, it is not what we call an electrical atmosphere; and want of industry and application. I am, sir, then the body is said to be electrified. your much obliged humble servant,
8. It is supposed, that all kinds of common B. FRANKLIN. matter do not attract and retain the electrical,
with equal strength and force, for reasons to Opinions and conjectures, concerning the be given hereafter: and that those called
Properties and Effects of the electrical electrics per se, as glass, &c. attract and reMatter, and the Means of preserving
tain it strongest, and contain the greatest Buildings, Ships, fc. from Lightning, quantity,
9. We know that the electrical fluid is in arising from Experiments and Observations made at Philadelphia, 1749-Golden common matter, because we can pump it out Fish. ---Extraction of effluvial Virtues by by the globe or tube. We know that common Electricity impracticable.
matter has near as much as it can contain,
because, when we add a little more to any 8 1. The electrical matter consists of par- portion of it, the additional quantity does not ticles extremely subtile, since it can permeate enter, but forms an electrical atmosphere.— common matter, even the densest metals, And we know that common matter has not with such ease and freedom as not to receive (generally) more than it can contain, otherany perceptible resistance.
wise, all loose portions of it would repel each 2. If any one should doubt whether the other, as they constantly do when they have electrical matter passes through the substance electric atmospheres. of bodies, or only over and along their sur 10. The beneficial uses of this electric faces, a shock from an electrified large glass fluid in the creation we are not yet well acjar, taken through his own body, will proba quainted with, though doubtless such there bly convince him.
are, and those very considerable ; 3. Electrical matter differs from common see some pernicious consequences that would matter in this, that the parts of the latter mu- attend a much greater proportion of it. For, tually attract, those of the former mutually had this globe we live on, as much of it in repel each other. Hence the appearing di- proportion as we can give to a globe of iron, vergency in a stream of electrified effluvia.
wood or the like, the particles of dust and 4. But though the particles of electrical other light matters that get loose from it, matter do repel each other, they are strongly would by virtue of their separate electrical attracted by all other matter.*
atmospheres, not only repel each other, but 5. From these three things, the extreme be repelled from the earth, and not easily be subtilty of the electrical matter, the mutual brought to unite with it again ; whence our repulsion of its parts, and the strong attraction air would continually be more and more clogbetween them and other matter, arise this ef- ged with foreign matter, and grow unfit for fect, that, when a quantity of electrical mat. respiration. This affords another occasion ter is applied to a mass of common matter, of for adoring that wisdom which has made all any bigness or length, within our observation things by weight and measure ! (which hath not already got its quantity, it is 11. If a piece of common matter be sus immediately and equally diffused through the pended entirely free from electrical matter, whole.
and a single particle of the latter be brought 6. Thus, common matter is a kind of spungę nigh, it will be attracted and enter the body to the electrical fluid. And as a spunge would and take place in the centre, or where the atreceive no water, if the parts of water were traction is every way equal. If more partinot smaller than the pores of the spunge; and cles enter, they take their places where the even then but slowly, if there were not a mu- balance is equal between the attraction of the tual attraction between those parts and the common matter, and their own mutual repulparts of the spunge; and would still imbibe it sion. It is supposed they form triangles, faster, if the mutual attraction among the parts whose sides shorten as their number increasof the water did not impede, some force being es; till the common matter has drawn in so required to separate them; and fastest, if, in
that its whole power of compressing stead of attraction, there were a mutual repul- those triangles by attraction, is equal to their sion among those parts, which would act in con- whole power of expanding themselves by rejunction with the attraction of the spunge: 80 pulsion; and then will such piece of matter is the case between the electrical and com- receive no more. mon matter.
12. When part of this natural proportion See the ingenious Basays on Electricity, in the of electrical Ruid is taken out of a piece of Transactions, by Mr. Ellicot.
common matter, the triangles formed by the
remainder, are supposed to widen by the mu- / an electrical atmosphere communicated to it, tual repulsion of the parts, until they occupy and we consider every side as a base on which the whole piece.
the particles rest, and by which they are at13. When the quantity of electrical fluid, tracted, one may see, by imagining a line taken from a piece of common matter, is re- from A to F, and another from E to G, that stored again, it enters the expanded triangles, the portion of the atmosphere included in F, being again compressed till there is room for A, E, G, has the line A, E, for its basis. So the whole.
the portion of atmosphere included in H, A, 14. To explain this: take two apples, or B, I, has the line A, B for its basis. And liketwo balls of wood or other matter, each hav- wise the portion included in K, B, C, L, has ing its own natural quantity of the electrical B, C, to rest on; and so on the other side of fluid. Suspend them by silk lines from the the figure. Now if you would draw off this ceiling. Apply the wire of a well-charged atmosphere with any blunt, smooth body, and phial, held in your hand, to one of them (A approach the middle of the side A, B, you Fig. 7,) and it will receive from the wire a must come very near, before the force of quantity of the electrical fluid; but will not your attractor exceeds the force or power with imbibe it, being already full. The fluid there which that side holds its atmosphere. But fore will flow round its surface, and form an there is a small portion between 1, B, K, that electrical atmosphere. Bring A into contact has less of the surface to rest on, and to be with B, and half the electrical fluid is com- attracted by, than the neighbouring portions, municated, so that each has now an electrical while at the same time there is a mutual reatmosphere, and therefore they repel each pulsion between its particles, and the particles other. Take away these atmospheres, by touch of those portions; therefore here you can get ing the balls, and leave them in their natural it with more ease, or at a greater distance. state; then having fixed a stick of sealing-wax Between F, A, H, there is a larger portion to the middle of the phial to hold it by, apply that has yet a less surface to rest on, and to the wire to A, at the same time the coating attract it; here, therefore, you can get it touches B. Thus will a quantity of the elec-away still more easily. But easiest of all trical fluid be drawn out of B, and thrown on between L, C, M, where the quantity is larA. So that A will have a redundance of this gest, and the surface to attract and keep it fluid, which forms an atmosphere round, and back the least. When you have drawn away B an exactly equal deficiency. Now, bring one of these angular portions of the fluid, these balls again into contact, and the elec- another succeeds in its place, from the nature trical atmosphere will not be divided between of fluidity, and the mutual repulsion beforeA and B, into two smaller atmospheres as be- mentioned ; and so the atmosphere continues fore; for B will drink up the whole atmos- flowing off at such angle, like a stream, till phere of A, and both will be found again in no more is remaining. The extremities of their natural state.
the portions of atmosphere over these angu15. The form of the electrical atmosphere lar parts, are likewise at a greater distance is that of the body it surrounds. This shape from the electrified body, as may be seen by may be rendered visible in a still air, by rais- the inspection of the above figure; the point ing a smoke from dry rosin dropt into a hot of the atmosphere of the angle C, being much tea-spoon under the electrified body, which farther from C than any other part of the atwill be attracted, and spread itself equally on mosphere over the lines C, B, or B, A: and, all sides, covering and concealing the body.* besides the distance arising from the nature And this form it takes, because it is attracted of the figure, where the attraction is less, the by all parts of the surface of the body, though particles will naturally expand to a greater it cannot enter the substance already replete. distance by their mutual repulsion. On these Without this attraction, it would not remain accounts we suppose electrified bodies disround the body, but dissipate in the air. charge their atmospheres upon unelectrified
16. The atmosphere of electrical particles bodies more easily, and at a greater distance surrounding an electrified sphere, is not more from their angles and points than from their disposed to leave it, or more easily drawn off smooth sides. Those points will also discharge from any one part of the sphere than another, into the air, when the body has too great an because it is equally attracted by every part. electrical atmosphere, without bringing any But that is not the case with bodies of any non-electric near, to receive what is thrown other figure. From a cube it is more easily off: for the air, though an electric per se, yet drawn at the corners than at the plain sides, has always more or less water and other nonand so from the angles of a body of any other electric matters mixed with it: and these atform, and still most easily from the angle that tract and receive what is so discharged. is most acute. Thus, if a body shaped as A, 17. But points have a property, by which B, C, D, E, in Fig. 8, be electrified, or have they draw on, as well as throw off the elec
trical fluid, at greater distances than blunt • See the second letter of date July 11, 1747.
bodies can. That is, as the pointed part of an