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CVI: TO PETER COLLINSON - Benjamin Franklin, The Works of Benjamin Franklin, Vol. II Letters and Misc. Writings 1735-1753 [1904]

Edition used:

The Works of Benjamin Franklin, including the Private as well as the Official and Scientific Correspondence, together with the Unmutilated and Correct Version of the Autobiography, compiled and edited by John Bigelow (New York: G.P. Putnam’s Sons, 1904). The Federal Edition in 12 volumes. Vol. II (Letters and Misc. Writings 1735-1753).

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CVI

TO PETER COLLINSON

Philadelphia, 23 November, 1753.

Dear Friend:—

In my last, via Virginia, I promised to send you per next ship, a small philosophical packet; but now, having got the materials (old letters and rough drafts) before me, I fear you will find it a great one. Nevertheless, as I am like to have a few days leisure before this ship sails, which I may not have again in a long time, I shall transcribe the whole and send it; for you will be under no necessity of reading it all at once, but may take it a little at a time, now and then of a winter evening. When you happen to have nothing else to do (if that ever happens), it may afford you some amusement.

B. Franklin.

Proposal of an Experiment to measure the Time taken up by an Electric Spark in moving through any given Space. By James Alexander, of New York.

read at the royal society, december 26, 1756.

If I remember right, the Royal Society made one experiment to discover the velocity of the electric fire, by a wire of about four miles in length, supported by silk, and by turning it forwards and backwards in a field, so that the beginning and end of the wire were at only the distance of two people, the one holding the Leyden bottle and the beginning of the wire, and the other holding the end of the wire and touching the ring of the bottle; but by this experiment no discovery was made, except that the velocity was extremely quick.

As water is a conductor as well as metals, it is to be considered, whether the velocity of the electric fire might not be discovered by means of water; whether a river, or lake, or sea, may not be made part of the circuit through which the electric fire passes, instead of the circuit all of wire, as in the above experiment.

Whether in a river, lake, or sea, the electric fire will not dissipate, and not return to the bottle? or will it proceed in straight lines through the water the shortest course possible back to the bottle?

If the last, then suppose one brook that falls into Delaware doth head very near to a brook that falls into Schuylkill; and let a wire be stretched and supported as before, from the head of one brook to the head of the other; and let the one end communicate with the water; and let one person stand in the other brook, holding the Leyden bottle; and let another person hold that end of the wire not in the water, and touch the ring of the bottle. If the electric fire will go as in the last question, then will it go down the one brook to Delaware or Schuylkill, and down one of them to their meeting, and up the other and the other brook; the time of its doing this may possibly be observable, and the farther upwards the brooks are chosen the more observable it would be.

Should this be not observable, then suppose the two brooks falling into Susquehanna and Delaware, and proceeding as before, the electric fire may, by that means, make a circuit round the North Cape of Virginia, and go many hundreds of miles, and in doing that, it would seem it must take some observable time.

If still no observable time is found in that experiment, then suppose the brooks falling the one into the Ohio and the other into Susquehanna or Potomac; in that the electric fire would have a circuit of some thousands of miles to go down Ohio to Mississippi, to the Bay of Mexico, round Florida, and round the South Cape of Virginia; which, I think, would give some observable time, and discover exactly the velocity.

But if the electric fire dissipates or weakens in the water, as I fear it does, these experiments will not answer.

Answer to the Foregoing

read at the royal society, december 26, 1756

Suppose a tube of any length, open at both ends, and containing a movable wire of just the same length that fills its bore. If I attempt to introduce the end of another wire into the same tube it must be done by pushing forward the wire it already contains, and the instant I press and move one end of that wire, the other end is also moved; and in introducing one inch of the same wire, I extrude, at the same time, an inch of the first from the other end of the tube.

If the tube be filled with water, and I inject an additional inch of water at one end, I force out an equal quantity at the other in the very same instant.

And the water forced out at one end of the tube is not the very same water that was forced in at the other end at the same time; it was only in motion at the same time.

The long wire, made use of in the experiment to discover the velocity of the electric fluid, is itself filled with what we call its natural quantity of that fluid, before the hook of the Leyden bottle is applied to one end of it.

The outside of the bottle being, at the time of such application, in contact with the other end of the wire, the whole quantity of electric fluid contained in the wire is, probably, put in motion at once.

For at the instant the hook connected with the inside of the bottle gives out, the coating, or outside of the bottle, draws in a portion of that fluid.

If such long wire contains precisely the quantity that the outside of the bottle demands, the whole will move out of the wire to the outside of the bottle, and the over quantity which the inside of the bottle contained, being exactly equal, will flow into the wire and remain there in the place of the quantity the wire had just parted with to the outside of the bottle.

But if the wire be so long as that one tenth (suppose) of its natural quantity is sufficient to supply what the outside of the bottle demands, in such case the outside will only receive what is contained in one tenth of the wire’s length, from the end next to it; though the whole will move so as to make room at the other end for an equal quantity issuing, at the same time, from the inside of the bottle.

So that this experiment only shows the extreme facility with which the electric fluid moves in metal; it can never determine the velocity.

And, therefore, the proposed experiment (though well imagined and very ingenious) of sending the spark round through a vast length of space, by the waters of Susquehanna, or Potomac, and Ohio, would not afford the satisfaction desired, though we could be sure that the motion of the electric fluid would be in that tract, and not under ground in the wet earth by the shortest way.

B. Franklin.

Physical and Meteorological Observations, Conjectures, and Suppositions

read at the royal society, june 3, 1756

The particles of air are kept at a distance from each other by their mutual repulsion.

Every three particles, mutually and equally repelling each other, must form an equilateral triangle.

All the particles of air gravitate towards the earth, which gravitation compresses them, and shortens the sides of the triangles; otherwise their mutual repellency would force them to greater distances from each other.

Whatever particles of other matter (not endued with that repellency) are supported in air must adhere to the particles of air, and be supported by them; for in the vacancies there is nothing they can rest on.

Air and water mutually attract each other. Hence water will dissolve in air, as salt in water.

The specific gravity of matter is not altered by dividing the matter, though the superficies be increased. Sixteen leaden bullets, of an ounce each, weigh as much in water as one of a pound, whose superficies is less.

Therefore the supporting of salt in water is not owing to its superficies being increased.

A lump of salt, though laid at rest at the bottom of a vessel of water, will dissolve therein, and its parts move every way, till equally diffused in the water; therefore there is a mutual attraction between water and salt. Every particle of water assumes as many of salt as can adhere to it; when more is added, it precipitates, and will not remain suspended.

Water, in the same manner, will dissolve in air, every particle of air assuming one or more particles of water. When too much is added, it precipitates in rain.

But there not being the same contiguity between the particles of air as of water, the solution of water in air is not carried on without a motion of the air, so as to cause a fresh accession of dry particles.

Part of a fluid, having more of what it dissolves, will communicate to other parts that have less. Thus, very salt water, coming in contact with fresh, communicates its saltness till all is equal, and the sooner, if there is a little motion of the water.

Even earth will dissolve or mix with air. A stroke of a horse’s hoof on the ground in a hot, dusty road will raise a cloud of dust that shall, if there be a light breeze, expand every way, till, perhaps, near as big as a common house. It is not by mechanical motion communicated to the particles of dust by the hoof that they fly so far, nor by the wind that they spread so wide; but the air near the ground, more heated by the hot dust struck into it, is rarefied and rises, and in rising mixes with the cooler air, and communicates of its dust to it, and it is at length so diffused as to become invisible. Quantities of dust are thus carried up in dry seasons; showers wash it from the air, and bring it down again. For, water attracting it stronger, it quits the air and adheres to the water.

Air, suffering continual changes in the degrees of its heat from various causes and circumstances, and, consequently, changes in its specific gravity, must therefore be in continual motion.

A small quantity of fire mixed with water (or degree of heat therein) so weakens the cohesion of its particles that those on the surface easily quit it, and adhere to the particles of air.

A greater degree of heat is required to break the cohesion between water and air.

Air moderately heated will support a greater quantity of water invisibly than cold air; for its particles being by heat repelled to a greater distance from each other, thereby more easily keep the particles of water that are annexed to them from running into cohesions that would obstruct, refract, or reflect the light.

Hence, when we breathe in warm air, though the same quantity of moisture may be taken up from the lungs, as when we breathe in cold air, yet that moisture is not so visible.

Water being extremely heated, that is, to the degree of boiling, its particles in quitting it so repel each other, as to take up vastly more space than before, and by that repellency support themselves, expelling the air from the space they occupy. That degree of heat being lessened, they again mutually attract; and having no air particles mixed to adhere to, by which they might be supported and kept at a distance, they instantly fall, coalesce, and become water again.

The water commonly diffused in our atmosphere never receives such a degree of heat from the sun, or other cause, as water has when boiling; it is not therefore supported by such heat, but by adhering to air.

Water being dissolved in and adhering to air, that air will not readily take up oil, because of the mutual repellency between water and oil.

Hence cold oils evaporate but slowly, the air having generally a quantity of dissolved water.

Oil being heated extremely, the air that approaches its surface will be also heated extremely; the water then quitting it, it will attract and carry off oil, which can now adhere to it. Hence the quick evaporation of oil heated to a great degree.

Oil being dissolved in air, the particles to which it adheres will not take up water.

Hence the suffocating nature of air impregnated with burnt grease, as from snuffs of candles and the like. A certain quantity of moisture should be every moment discharged and taken away from the lungs; air that has been frequently breathed is already overloaded, and for that reason can take no more, so will not answer the end. Greasy air refuses to touch it. In both cases suffocation for want of the discharge.

Air will attract and support many other substances.

A particle of air loaded with adhering water, or any other matter is heavier than before, and would descend.

The atmosphere supposed at rest, a loaded descending particle must act with a force on the particles it passes between, or meets with, sufficient to overcome, in some degree, their mutual repellency, and push them nearer to each other.

lf1438-02_figure_012

Thus, supposing the particles A, B, C, D, and the other near them, to be at the distance caused by their mutual repellency (confined by their common gravity), if A would descend to E, it must pass between B and C; when it comes between B and C, it will be nearer to them than before, and must either have pushed them nearer to F and G, contrary to their mutual repellency, or pass through by a force exceeding its repellency with them. It then approaches D, and, to move it out of the way, must act on it with a force sufficient to overcome its repellency with the two next lower particles, by which it is kept in its present situation.

Every particle of air, therefore, will bear any load inferior to the force of these repulsions.

Hence the support of fogs, mists, clouds.

Very warm air, clear, though supporting a very great quantity of moisture, will grow turbid and cloudy on the mixture of a colder air, as foggy, turbid air will grow clear by warming.

Thus the sun, shining on a morning fog, dissipates it; clouds are seen to waste in a sunshiny day.

But cold condenses and renders visible the vapor; a tankard or decanter filled with cold water will condense the moisture of warm, clear air on its outside, where it becomes visible as dew, coalesces into drops, descends in little streams.

The sun heats the air of our atmosphere most near the surface of the earth; for there, besides the direct rays, there are many reflections. Moreover the earth, itself being heated, communicates of its heat to the neighbouring air.

The higher regions, having only the direct rays of the sun passing through them, are comparatively very cold. Hence the cold air on the tops of mountains, and snow on some of them all the year, even in the torrid zone. Hence hail in summer.

If the atmosphere were all of it (both above and below) always of the same temper as to cold or heat, then the upper air would always be rarer than the lower, because the pressure on it is less; consequently lighter, and therefore would keep its place.

But the upper air may be more condensed by cold than the lower air by pressure; the lower more expanded by heat than the upper, for want of pressure. In such case the upper air will become the heavier, the lower the lighter.

The lower region of air being heated and expanded heaves up and supports for some time the colder, heavier air above, and will continue to support it while the equilibrium is kept. Thus water is supported in an inverted open glass, while the equilibrium is maintained by the equal pressure upwards of the air below; but the equilibrium by any means breaking, the water descends on the heavier side and the air rises into its place.

The lifted heavy, cold air over a heated country, becoming by any means unequally supported, or unequal in its weight, the heaviest part descends first, and the rest follows impetuously. Hence gusts after heats, and hurricanes in hot climates. Hence the air of gusts and hurricanes cold, though in hot climates and seasons; it coming from above.

The cold air descending from above, as it penetrates our warm region full of watery particles, condenses them, renders them visible, forms a cloud thick and dark, overcasting sometimes, at once large and extensive; sometimes, when seen at a distance, small at first, gradually increasing; the cold edge or surface of the cloud condensing the vapors next it, which form smaller clouds that join it, increase its bulk, it descends with the wind and its acquired weight, draws nearer the earth, grows denser with continual additions of water, and discharges heavy showers.

Small black clouds thus appearing in a clear sky, in hot climates, portend storms, and warn seamen to hand their sails.

The earth turning on its axis in about twenty-four hours, the equatorial parts must move about fifteen miles in each minute; in northern and southern latitudes this motion is gradually less to the poles, and there nothing.

If there was a general calm over the face of the globe, it must be by the air’s moving in every part as fast as the earth or sea it covers.

He that sails or rides has insensibly the same degree of motion as the ship or coach with which he is connected. If the ship strikes the shore, or the coach stops suddenly, the motion continuing in the man, he is thrown forward. If a man were to jump from the land into a swift-sailing ship, he would be thrown backward (or towards the stern), not having at first the motion of the ship.

He that travels by sea or land towards the equinoctial, gradually acquires motion; from it, loses.

But if a man were taken up from latitude 40 (where suppose the earth’s surface to move twelve miles per minute) and immediately set down at the equinoctial, without changing the motion he had, his heels would be struck up, he would fall westward. If taken up from the equinoctial and set down in latitude 40, he would fall eastward.

The air under the equator, and between the tropics, being constantly heated and rarefied by the sun, rises. Its place is supplied by air from northern and southern latitudes, which, coming from parts where the earth and air had less motion, and not suddenly acquiring the quicker motion of the equatorial earth,1 appears an east wind blowing westward, the earth moving from west to east, and slipping under the air.

Thus when we ride in a calm it seems a wind against us; if we ride with the wind, and faster, even that will seem a small wind against us.

The air rarefied between the tropics, and rising, must flow in the higher region north and south. Before it rose, it had acquired the greatest motion the earth’s rotation could give it. It retains some degree of this motion, and descending in higher latitudes, where the earth’s motion is less, will appear a westerly wind, yet tending towards the equatorial parts, to supply the vacancy occasioned by the air of the lower regions flowing thitherwards.

Hence our general cold winds are about northwest; our summer cold gusts the same.

The air in sultry weather, though not cloudy, has a kind of haziness in it, which makes objects at a distance appear dull and indistinct. This haziness is occasioned by the great quantity of moisture equally diffused in that air. When, by the cold wind blowing down among it, it is condensed into clouds, and falls in rain, the air becomes purer and clearer. Hence, after gusts, distant objects appear distinct, their figures sharply terminated.

Extreme cold winds congeal the surface of the earth, by carrying off its fire. Warm winds, afterwards blowing over that frozen surface, will be chilled by it. Could that frozen surface be turned under, and a warmer turned up from beneath it, those warm winds would not be chilled so much.

The surface of the earth is also sometimes much heated by the sun; and such heated surface, not being changed, heats the air that moves over it.

Seas, lakes, and great bodies of water, agitated by the winds, continually change surfaces; the cold surface in winter is turned under by the rolling of the waves, and a warmer turned up; in summer, the warm is turned under, and colder turned up. Hence the more equal temper of sea water, and the air over it. Hence, in winter, winds from the sea seem warm, winds from the land cold. In summer, the contrary.

Therefore the lakes northwest of us,1 as they are not so much frozen nor so apt to freeze as the earth, rather moderate than increase the coldness of our winter winds.

The air over the sea being warmer, and therefore lighter in winter than the air over the frozen land, may be another cause of our general northwest winds, which blow off to sea at right angles from our North American coast; the warm, light sea air rising, the heavy, cold land air pressing into its place.

Heavy fluids descending frequently form eddies or whirlpools, as is seen in a funnel where the water acquires a circular motion, receding every way from a centre, and leaving a vacancy in the middle, greatest above, and lessening downwards, like a speaking-trumpet, its big end upwards.

Air descending or ascending may form the same kind of eddies or whirlings, the parts of air acquiring a circular motion, and receding from the middle of the circle by a centrifugal force, and leaving there a vacancy, if descending, greatest above, and lessening downwards; if ascending, greatest below, and lessening upwards, like a speaking-trumpet, standing its big end on the ground.

When the air descends with violence in some places, it may rise with equal violence in others, and form both kinds of whirlwinds.

The 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 sides, the whirling air, as an arch, preventing; it must then press in at the open ends.

The greatest pressure inwards must be at the lower end, the greatest weight of the surrounding atmosphere being there. The air entering rises within, and carries up dust, leaves, and even heavier bodies that happen in its way as the eddy or whirl passes over land.

If it passes over water, the weight of the surrounding atmosphere forces up the water into the vacuity, part of which, by degrees, joins with the whirling air, and adding weight, and receiving accelerated motion, recedes still farther from the centre or axis of the trump as the pressure lessens, and at last, as the trump widens, is broken into small particles, and so united with air as to be supported by it, and become black clouds at the top of the trump.

Thus these eddies may be whirlwinds at land, water-spouts at sea. A body of water so raised may be suddenly let fall when the motion, &c., has not strength to support it, or the whirling arch is broken so as to admit the air; falling in the sea it is harmless, unless ships happen under it; but if in the progressive motion of the whirl it has moved from the sea over the land, and then breaks, sudden, violent, and mischievous torrents are the consequences.

B. Franklin.

end of vol. ii

[1 ]Probably the ground is never so dry.—F.

[1 ]We afterwards found that it failed after one stroke with a large bottle, and the continuity of the gold appearing broken, and many of its parts dissipated, the electricity could not pass the remaining parts without leaping from part to part through the air, which always resists the motion of this fluid, and was probably the cause of the gold’s not conducting so well as before; the number of interruptions in the line of gold, making, when added together, a space larger, perhaps, than the striking distance.—F.

[1 ]The river that washes one side of Philadelphia, as the Delaware does the other; both are ornamented with the summer habitations of the citizens and the agreeable mansions of the principal people of this colony.—F.

[2 ]As the possibility of this experiment has not been easily conceived, I shall here describe it. Two iron rods, about three feet long, were planted just within the margin of the river, on the opposite sides. A thick piece of wire, with a small round knob at its end, was fixed on the top of one of the rods, bending downwards, so as to deliver commodiously the spark upon the surface of the spirit. A small wire fastened by one end to the handle of the spoon, containing the spirit, was carried across the river and supported in the air by the rope commonly used to hold by in drawing the ferry-boats over. The other end of this wire was tied round the coating of the bottle; which being charged, the spark was delivered from the hook to the top of the rod standing in the water on that side. At the same instant the rod on the other side delivered a spark into the spoon and fired the spirit, the electric fire returning to the coating of the bottle, through the handle of the spoon and the supported wire connected with them.

That the electric fire thus actually passes through the water, has since been satisfactorily demonstrated to many by an experiment of Mr. Kinnersley’s, performed in a trough of water about ten feet long. The hand, being placed under water in the direction of the spark (which always takes the straight or shortest course, if sufficient, and other circumstances are equal), is struck and penetrated by it as it passes.—F.

[1 ]An electrified bumper is a small, thin, glass tumbler, nearly filled with wine, and electrified as the bottle. This when brought to the lips gives a shock, if the party be close shaved, and does not breathe on the liquor.—April 29, 1749.—F.

[1 ]This was tried with a bottle containing about a quart. It is since thought that one of the large glass jars mentioned in these papers might have killed him, though wet.—F.

[1 ]We have since fired spirits without heating them, when the weather is warm. A little, poured into the palm of the hand, will be warmed sufficiently by the hand, if the spirit be well rectified. Ether takes fire most readily.—F.

[1 ]These facts, though related in several accounts, are now doubted: since it has been observed that the parts of a bell-wire which fell on the floor, being broken and partly melted by lightning, did actually burn into the boards. (See Philosophical Transactions, vol. li., Part I.) And Mr. Kinnersley has found that a fine iron wire, melted by electricity, has had the same effect.—F.

[1 ]Franklin’s wife was a Miss Read.

[1 ]His son, William, had been an officer in the Pennsylvania forces raised for an expedition against Canada, in the year 1746.

[1 ]In a letter from James Logan to Mr. Collinson, dated February 14, 1750, he says: “Our Benjamin Franklin is certainly an extraordinary man, one of a singular good judgment, but of equal modesty. He is clerk of our Assembly, and there, for want of other employment, while he sat idle, he took it into his head to think of magical squares, in which he outdid Frenicle himself, who published above eighty pages in folio on that subject alone.”

[1 ]In the plate they are distinguished by dashed or dotted lines, as different as the engraver could well make them.—F.

[1 ]Professor Bache, of the University of Pennsylvania, has shown that the eclipse of the moon here alluded to happened in the evening of the 21st of October, 1743; as may be seen in his tract entitled. “An Attempt to Fix the Date of Observation of Dr. Franklin, in Relation to the Northeast Storms of the Atlantic Coast of the United States,” published in the Journal of the Franklin Institute, in the year 1833. It appears that Dr. Franklin was the first discoverer of the above facts respecting northeast storms.—Sparks.

[1 ]A Swedish botanist, sent by the Swedish government, at the suggestion of Linnæus, to make a botanical tour of North America. He arrived in 1748 and returned in 1751, having travelled and collected specimens in New York, Pennsylvania, and Canada. He published an account of his travels in Swedish in 1753-1761 in three vols. It was translated into English, Dutch, and German.—Editor.

[2 ]Lewis Evans, author of Geographical, Historical, Political, Philosophical, and Mechanical Essays, of some other tracts, and of a map of the Middle Colonies.

[1 ]The cushion being afterwards covered with a long flap of buckskin, which might cling to the globe, and care being taken to keep that flap of a due temperature between too dry and too moist, we found so much more of the electric fluid was obtained as that one hundred and fifty turns were sufficient. 1753.—F.

[1 ]See the ingenious essays on Electricity, in the Transactions, by Mr. Ellicot.—F.

[1 ]See Supra, p. 182.

[1 ]See the first sixteen sections of the former paper, No. LXI.

[1 ]See § 10 of paper No. LXI.

[1 ]In the dark the electric fluid may be seen on the cushion in two semi-circles or half-moons, one on the fore part, the other on the back part of the cushion, just where the globe and cushion separate. In the fore crescent the fire is passing out of the cushion into the glass, in the other it is leaving the glass and returning into the back part of the cushion. When the prime conductor is applied to take it off the glass, the back crescent disappears.—F.

[2 ]Gilt paper, with the gilt face next the glass, does well.

[1 ]See paper No. LXI., § 15.

[1 ]Dr. Samuel Johnson was the first president of King’s (now Columbia) College, New York. This letter appears to have been written at the time of the first establishment of the College of Philadelphia, the presidency of which institution had been offered to him, but was declined.

[1 ]Mr. Bowdoin was at this time twenty-three years old. He became distinguished afterwards as a philosopher and statesman, being one of the principal founders and the first president of the American Academy of Arts and Sciences. He took an active and prominent part in the events of the American Revolution, and was subsequently governor of Massachusetts.—Sparks.

[1 ]A copy of this letter was found among Governor Bowdoin’s papers, without the name of the person to whom it was addressed.—Sparks.

[1 ]This proposition is since found to be too general, Mr. Wilson having discovered that melted wax and rosin will also conduct.

[1 ]The experiment here mentioned was thus made. An empty phial was stopped with a cork. Through the cork passed a thick wire, as usual in the Leyden experiment, which wire almost reached the bottom. Through another part of the cork passed one leg of a small glass siphon; the other leg on the outside came down almost to the bottom of the phial. This phial was held a short time in the hand, which, warming and of course rarefying the air within, drove a small part of it out through the siphon. Then a little red ink in a tea-spoon was applied to the opening of the outer leg of the siphon; so that as the air within cooled, a little of the ink might rise in that leg. When the air within the bottle came to be of the same temperature of that without, the drop of red ink would rest in a certain part of the leg. But the warmth of a finger applied to the phial would cause that drop to descend, as the least outward coolness applied would make it ascend. When it had found its situation, and was at rest, the wire was electrified by a communication from the prime conductor. This was supposed to give an electric atmosphere to the wire within the bottle, which might likewise rarefy the included air, and of course depress the drop of ink in the siphon. But no such effect followed.—F.

[1 ]The prospect of a rupture between the English and French governments in 1750-51 were so threatening that the friendship of the Indian tribes became a matter of supreme importance, and how to secure it occupied the attention of leading men throughout the colonies. In the appendix to the second edition of a pamphlet entitled The Importance of Gaining and Preserving the Friendship of the Indians to British Interests Considered, London, 1782, is a letter which bears so many distinctive traces of Franklin’s authorship that it has seemed to merit a place in this collection.

The editor is happy to acknowledge his obligations to Professor Edward Eggleston for calling his attention to this letter, which that gentleman found in the Harvard College Library. “I think,” says Professor Eggleston, in a note to the editor, “the pamphlet is anonymous, but I have a minute that the author is Archibald Kennedy. The first edition, N. Y., 1751, and the letter I believe to be Franklin’s was dated at Philadelphia and addressed to the printer of the first edition.—Parker.”

[1 ]Nor will tables which are accurately calculated at one period, necessarily continue to be correct in the same country at another period. The chances of life have been ascertained to be greater in Europe during the last half century than they were formerly.—W. Phillips.

[1 ]It is a curious fact that to this tract the world is largely, if not entirely, indebted for a book which, in its day, produced a remarkable sensation, and the theories of which are still occasionally debated. Malthus’ Essay on Population would probably never have been written but for the support of his theory which he was able to extract from the 22d clause of this paper. In that clause Franklin, with his habitual caution, referring to the number of “English souls” then in North America, says: “This million doubling, suppose but once in twenty-five years, will in another century be more than the people of England.” Malthus accepts this rather hypothetical statement as evidence of a demonstrated fact, and proceeds to build upon it his chimerical theory that the population of the earth increases in a geometrical ratio, while the means for its subsistence increases only in an arithmetical ratio William Godwin wrote a reply to Malthus entitled An Enquiry concerning the Power of Increase in the Numbers of Mankind, being an Answer to Mr. Malthus’ Essay on that Subject, which was published in 1820. He did not see any way of demolishing Malthus but by first trying to demolish the statement of Franklin. “Dr. Franklin,” he says, “is in this case particularly the object of our attention, because he was the first man who started the idea of the people of America being multiplied by procreation so as to double every twenty-five years. Dr. Franklin, born in Boston, was eminently an American patriot; and the paper from which these extracts are taken, was expressly written to exalt the importance and glory of his country.” Mr. Godwin, who is open to the suspicion of having taken his knowledge of Franklin’s paper at second-hand, and to have never read more of it than was quoted by Malthus, stumbles into a curious blunder as to its date. He says (p. 119) “it was written in 1731 when the author was twenty-five years of age,” meaning evidently to imply thereby that it was the work of an immature political economist. The fact was that Franklin’s paper was written in 1751, when he was forty-five years of age. Franklin understood what he was writing about much better than Godwin, and time and science have fully justified all the statements which Godwin contested.

[1 ]The explanation here referred to will be found in the following paragraph of a letter written to Franklin by Bowdoin on 21 Dec., 1751. Franklin had in September of the same year given Mr. Kinnersley a letter of introduction to Bowdoin, to pave the way for a course of lectures in Boston on electricity, which Mr. Kinnersley had prepared and delivered in Philadelphia:

“The electrical fire passing through the air has the same crooked direction as lightning. This appearance I endeavour to account for thus. Air is an electric per se; therefore there must be a mutual repulsion between air and the electrical fire. A column or cylinder of air having the diameter of its base equal to the diameter of the electrical spark, intervenes between that part of the body which the spark is drawn from and that of the body it aims at. The spark acts upon this column, and is acted upon by it more strongly than any other neighbouring portion of air. The column being thus acted upon, becomes more dense, and, being more dense, repels the spark more strongly; its repellency being in proportion to its density. Having acquired by being condensed a degree of repellency greater than its natural, it turns the spark out of its straight course, the neighbouring air, which must be less dense, and therefore has a smaller degree of repellency, giving it a more ready passage. The spark having taken a new direction must now act on, or most strongly repel, the column of air which lies in that direction, and consequently must condense that column in the same manner as the former, when the spark must again change its course, which course will be repeatedly changed, till the spark reaches the body that attracted it.”—Ed.

[1 ]The Rev. Ebenezer Kinnersley was a professor in the College of Philadelphia.—Editor.

[2 ]The experiments here referred to were described in the following letter from Mr. Kinnersley to Dr. Franklin:

[Boston] 3 February, 1752.

Sir:—

I have the following experiments to communicate. I held in one hand a wire, which was fastened at the other end to the handle of a pump, in order to try whether the stroke from the prime conductor, through my arms, would be any greater than when conveyed only to the surface of the earth, but could discover no difference.

I placed the needle of a compass on the point of a long pin, and, holding it in the atmosphere of the prime conductor, at the distance of about three inches, found it to whirl round like the flyers of a jack, with great rapidity.

I suspended with silk a cork ball, about the bigness of a pea and presented to it rubbed amber, sealing-wax, and sulphur, by each of which it was strongly repelled; then I tried rubbed glass and China, and found that each of these would attract it, until it became electrified again, and then it would be repelled as at first; and while thus repelled by the rubbed glass or China, either of the others when rubbed would attract it. Then I electrified the ball with the wire of a charged phial, and presented to it rubbed glass (the stopper of a decanter) and a China tea-cup, by which it was as strongly repelled as by the wire but when I presented either of the other rubbed electrics, it would be strongly attracted, and when I electrified it by either of these, till it became repelled, it would be attracted by the wire of the phial, but be repelled by its coating.

These experiments surprised me very much, and have induced me to infer the following paradoxes.

1. If a glass globe be placed at one end of a prime conductor, and a sulphur one at the other end, both being equally in good order, and in equal motion, not a spark of fire can be obtained from the conductor; but one globe will draw out as fast as the other gives in.

2. If a phial be suspended on the conductor, with a chain from its coating to the table, and only one of the globes be made use of at a time, twenty turns of the wheel, for instance, will charge it, after which, so many turns of the other wheel will discharge it, and as many more will charge it again.

3. The globes being both in motion, each having a separate conductor, with a phial suspended on one of them, and the chain of it fastened to the other, the phial will become charged; one globe charging positively, the other negatively.

4. The phial being thus charged, hang it in like manner on the other conductor, set both wheels a going again, and the same number of turns that charged it before will now discharge it, and the same number repeated will charge it again.

5. When each globe communicates with the same prime conductor, having a chain hanging from it to the table, one of them, when in motion (but which I cannot say), will draw fire up through the cushion, and discharge it through the chain; the other will draw it up through the chain, and discharge it through the cushion.

[1 ]The discoveries of the late ingenious Mr. Symmer, on the positive and negative electricity produced by the mutual friction of white and black silk, etc., afford hints for farther improvements to be made with this view.—F.

[1 ]Dr. Perkins, of Boston, had asked Franklin for the number that had died of inoculation in Philadelphia, at the instance of Dr. Douglass, who designed to write something on the small-pox.

[1 ]See this paper Supra, p. 338.

[1 ]This is the only evidence in our literature, so far as I know, that any of this sect, for whose principles Fenelon suffered and Molinos died, ever found a refuge in the United States.—Ed.

[1 ]The bookseller in London, who first published Franklin’s papers on electricity.

[1 ]The paper alluded to, of which fifty copies were struck off for distribution, was entitled, Letters relating to a Transit of Mercury over the Sun, which is to happen May 6, 1753.

[1 ]As early as 1743, Franklin had endeavored to procure the establishment of an Academy in Philadelphia. His efforts were not successful till 1749, when, chiefly through his instrumentality, the Academy was instituted and went into operation. Franklin was chosen the first president of the Board of Trustees. From this institution arose, first the College of Philadelphia, and afterwards the present University of Pennsylvania. The Reverend William Smith was appointed Provost of the Academy in 1754, and he filled that office, at the head of the Academy and College successively, for the period of thirty-seven years, till the University was founded in 1791. A full account of these institutions, in their various stages, may be seen in Wood’s History of the University of Pennsylvania, contained in the third volume of the Memoirs of the Historical Society of Pennsylvania.

[2 ]A General Idea of the College of Mirania.—Stuber.

[1 ]The Rev. Francis Alison, afterwards Vice-Provost of the College in Philadelphia.—Stuber.

[2 ]Theophilus Grew, afterwards Professor of Mathematics in the College.—Stuber.

[3 ]Those assistants were at that time Charles Thomson, afterwards Secretary of Congress, Paul Jackson, and Jacob Duché.—Stuber.

[1 ]The name given to the principal or head of the ideal college, the system of education in which has nevertheless been nearly realized, or followed as a model, in the College and Academy of Philadelphia and some other American seminaries for many years past.—Stuber.

[1 ]The quotation alluded to (from the London Monthly Review for 1749) was judged to reflect too severely on the discipline and government of the English Universities of Oxford and Cambridge, and was expunged from the following editions of this work.—Stuber.

[1 ]This letter was first printed in the Gentleman’s Magazine for January, 1834, as contained in the Diary of Mr. Thomas Green. The person who communicated it to the Magazine says the original manuscript, from which he transcribed the letter, ends thus abruptly, and that the remainder could not be recovered. He conjectures that the words of Milton, alluded to by the writer are the following:

  • “Yet sometimes nations will decline so low
  • From virtue, which is reason, that no wrong
  • But justice, and some fatal curse annex’d,
  • Deprives them of their outward liberty,
  • Their inward lust.’
  • Paradise Lost, xii., 97.

[1 ]Mr. Bowdoin replied as follows, in a letter dated at Boston, November 12th:—“Our Indians formerly (as yours now) made great complaints of the abuses they suffered from private traders, which induced the government to erect truckhouses for them; where they have since been supplied with the goods they wanted in a much better manner both in regard of the quality and price of them, and with more certainty than the private traders could. The government used to put an advance on the goods supplied, but now they let the Indians have them in the small quantities they want at the same rate they are purchased here in the wholesale way, and allow them for their peltry what it sells for here; and, notwithstanding, they are frequently complaining about the prices of the exchanged commodities, and say that the French supply them at a cheaper rate, and allow them more for their skins than we do; but some allowance is to be made for this account of theirs.

“The best method we can go into, is to supply them with what they want at the cheapest rate possible, which will not only undermine the French trade with them, but in proportion thereto bring them into our interest and friendship against the French; for trade and commerce between nation and nation, especially when carried on to mutual advantage, have a natural tendency to beget and confirm a mutual and lasting friendship. Another good effect of this method is, that it prevents the Indians from being concerned with private traders; for not being able to supply them at so low a rate as the government, the Indians will not trade with them, and it is therefore a more effectual bar against private trade than all the laws that can be invented.

Our truckhouses are built in form of a square, each side one hundred and fifty feet or more, at each corner a flanker, in which is a couple of cannon; three sides of the square are built upon to accommodate the garrison and for storehouses, the whole being surrounded with palisades.”

[1 ]This treaty, or rather conference, was held at Carlisle, in Pennsylvania, with deputies from several tribes of western Indians. See Sparks’s Life of Washington, 2d edition, p. 25.

[2 ]To this inquiry Mr. Colden replied, November 19th:—“We have at present no law in this province for restraining the trade to Canada, except that by which a duty is laid on Indian goods sold out of the city of Albany and applied for support of the garrison at Oswego. It is certain that a very considerable trade is carried on between Albany and Canada by means of the Caghnawaga or French Indians, all of them deserters from the Five Nations. When I was last at Albany, there were at least two hundred of them, stout young fellows, at one time in the town. The Indians have passports from the governor of Canada, and I therefore conclude that this trade is thought beneficial to the French interest, and it may be a great inducement to our Indians to desert, by the benefit they receive from it; for none are allowed to be the carriers between Albany and Canada but French Indians.”

[1 ]President of Yale College.

[1 ]See a paper on this subject, by the late ingenious Mr. Hadley, in the Philosophical Transactions, wherein this hypothesis for explaining the trade-winds first appeared.—F.

[1 ]In Pennsylvania.