Benjamin Franklin Papers

From Benjamin Franklin to Peter Collinson, 25 May 1747

To Peter Collinson

Copy: American Academy of Arts and Sciences1

Philada. May 25. 17472


In my last3 I informed you that In pursuing our Electrical Enquiries, we had observ’d some particular Phaenomena, which we lookt upon to be new, and of which I promised to give you some Account; tho’ I apprehended they might possibly not be new to you, as so many Hands are daily employed in Electrical Experiments on your Side the Water, some or other of which would probably hit on the same Observations.

The first is the wonderful Effect of Points4 both in drawing off and throwing off the Electrical Fire. For Example,

Place an Iron Shot of three or four Inches Diameter on the Mouth of a clean dry Glass Bottle. By a fine silken Thread from the Ceiling, right over the Mouth of the Bottle, suspend a small Cork Ball, about the Bigness of a Marble: the Thread of such a Length, as that the Cork Ball may rest against the Side of the Shot. Electrify the Shot, and the Ball will be repelled to the Distance of 4 or 5 Inches, more or less according to the Quantity of Electricity. When in this State, if you present to the Shot the Point of a long, slender, sharp Bodkin at 6 or 8 Inches Distance, the Repellency is instantly destroy’d, and the Cork flies to it.5 A blunt Body must be brought within an Inch, and draw a Spark to produce the same Effect. To prove that the Electrical Fire is drawn off by the Point: if you take the Blade of the Bodkin out of the wooden Handle, and fix it in a Stick of Sealing Wax, and then present it at the Distance aforesaid6 no such Effect follows; but slide7 one Finger along the Wax till you touch the Blade, and the Ball flies to the Shot immediately. If you present the Point in the Dark, you will see, sometimes at a Foot Distance and more, a Light gather upon it like that of a Fire-Fly or Glow-Worm; the less sharp the Point, the nearer you must bring it to observe this Light: and at whatever Distance you see the Light, you may draw off the Electrical Fire, and destroy the Repellency. If a Cork Ball, so suspended, be repelled by the Tube, and a Point be presented quick to it, tho’ at a considerable Distance, tis surprizing to see how suddenly it flies back to the Tube. Points of Wood do as well8 as those of Metal,9 provided the Wood is not dry.1

To shew that Points will throw off,2 as well as draw off the Electrical Fire: Lay a long sharp Needle upon the Shot, and you can not electrise the Shot, so as to make it repel the Cork Ball.3 Fix4 a Needle to the End of a suspended Gun Barrel,5 so as to point beyond it like a little Bayonet, and while it remains there, the Gun Barrel can not be electrised (by the Tube applied to the other End) so as to give a Spark;6 the Fire is7 continually running out silently at the Point. In the Dark you may see it make the same Appearance as it does in the Case before mentioned.

The Repellency between the Cork Ball and Shot is likewise destroy’d; 1. By sifting fine Sand on it; this does it gradually: 2. By breathing on it: 3. By making a Smoke about it from burning Wood:* 4. By Candle Light,8 even tho’ the Candle is at a Foot Distance: These do it suddenly. The Light of a bright Coal from a Wood Fire, and the Light of a red-hot Iron do it likewise; but not at so great a Distance. Smoke from dry Rosin dropt into a little hot Letter Founders Ladle2 under the Shot does not destroy the Repellency; but is attracted by both the Shot and the Cork-Ball, forming proportionable Atmospheres round them, making them look beautifully; somewhat like some of the Figures in Burnets or Whiston’s Theory of the Earth.3

N.B. This Experiment should be made [in a closet] where the Air is very still.4

The Light of the Sun thrown strongly on both Shot and Cork by a Looking Glass for a long Time together does not impair the Repellency in the least. This Difference between Fire Light and Sun Light is another Thing that seems new and extraordinary to us.5

We had for some Time been of Opinion, that the Electrical Fire was not created by Friction, but collected, being an Element6 diffused among, and attracted by other Matter, particularly by Water and Metals. We7 had even discovered and demonstrated its Afflux to the Electrical Sphere, as well as its Efflux, by Means of little light Wind-Mill Wheels8 made of stiff Paper Vanes, fixt obliquely, and turning freely on fine Wire Axes. Also by little Wheels of the same Matter, but formed like Water Wheels. Of the Disposition and Application of which Wheels, and the various Phaenomena resulting, I could, if I had Time, and it were necessary,9 fill you a Sheet.

The Impossibility of Electrising one’s self (tho’ standing on Wax) by Rubbing the Tube and drawing the Fire from it: and the Manner of doing it by passing the Tube near a Person, or Thing standing on the Floor &c. had also occurred to us some Months before Mr. Watsons ingenious Sequel1 came to hand; and these were some of the new Things I intended to have communicated to you: But now I need only mention some Particulars not hinted in that Piece, with our Reasonings thereon; tho’ perhaps the latter might well enough be spared.

1. A Person standing on Wax and rubbing the Tube; and another Person on Wax drawing the Fire, they will both of them (provided they do not stand so as to touch one another) appear to be electrised to a Person standing on the Floor; that is, he will perceive a Spark on approaching each of them.2

2. But if the Persons standing3 on Wax touch one another during the exciting of the Tube, neither of them will appear to be electrised.

3. If they touch one another after exciting the Tube, and drawing the Fire as aforesaid, there will be a stronger Spark between them than was between either of them and the Person on the Floor.

4. After such strong Spark, neither of them discovers any Electricity.

These Appearances we attempt to account for thus. We suppose as aforesaid, That Electrical Fire is a common Element, of which every one of the three Persons4 abovementioned has his equal Share before any Operation is begun with the Tube. A who stands on Wax, and rubs the Tube, collects the Electrical Fire from himself into the Glass; and his Communication with the common Stock being cut off by the Wax, his Body is not again immediately supply’d. B, who stands upon Wax likewise, passing his Knuckle along near the Tube, receives the Fire which was collected by the Glass from A; and his Communication with the common Stock being likewise cutt off, he retains the additional Quantity received. To C, standing on the Floor, both appear to be electrised; for he having only the middle Quantity of Electrical Fire receives a Spark on approaching B, who has an over-quantity, but gives one to A, who has an under-quantity. If A and B touch5 each other, the Spark between them6 is stronger, because the Difference between them is greater. After such Touch, there is no Spark between either of them and C; because the Electrical Fire in all is reduced to the original Equality. If they touch while Electrising, the Equality is never destroyed, the Fire only circulating. Hence have arisen some new Terms among us. We say B (and other Bodies alike circumstanced) are7 electrised positively; A negatively: Or rather B is electrised plus and A minus. And we daily in our Experiments electrise Bodies plus or minus as we think proper. These Terms we may use till your Philosophers give us better.8 To electrise plus or minus, no more needs to be known than this; that the Parts of the Tube or Sphere, that are rub’d, do, in the Instant of the Friction, attract the Electrical Fire, and therefore take it from the Thing rubbing: the same Parts immediately, as the Friction upon them ceases, are disposed to give the Fire they have received, to any Body that has less. Thus you may circulate it, as Mr. Watson has shewn; You may also accumulate or subtract it upon, or from any Body, as you connect it9 with the Rubber or with the Receiver; the Communication with the common Stock being cut off. We think that ingenious Gentleman was deceived, when he imagined (Page [64] of the Sequel)1 that the Electrical Fire came down the Wire from the Cieling to the Gun Barrel, thence to the Sphere and so electrised the Machine,2 the Man turning the Wheel &c. We suppose it was driven off and not brought on thro’ that Wire; and that the Machine and Man &c. were electrized minus, i.e. had less electrical Fire in them than Things in common.

As the Vessel is just sailing,3 I can not give you so large an Account of American Electricity as I intended. I shall only mention a few Particulars more.4 We find granulated Lead better to fill the Vial with than Water, being easily warmed, and keeping the Vial5 warm and dry in damp Air. We fire Spirits with the Wire of the Phial. We light Candles just blown out, by drawing a Spark among the Smoke between the Wire and Snuffers. We represent Lightning, by passing the Wire, in the Dark, over a China Plate, that has gilt Flowers; or applying it to gilt Frames of Looking Glasses &c. We electrise a Person 20 or more Times running, with the Touch of the Finger on the Wire, thus;* He stands on Wax; give him the electrised Bottle in his Hand; touch the Wire with your Finger, and then touch his Hand or Face, there are Sparks every Time.7 We encrease the Force of the electrical Kiss vastly, thus; Let A and B stand on Wax;8 give one of them the electrised Vial in Hand; let the other take hold of the Wire; there will be a small Spark; but when their Lips approach, they will be struck and shockt. The same, if C and D9 (standing also on Wax) and joyning Hands with A and B, salute or shake Hands. We suspend by a fine Silk Thread a Counterfeit Spider, made of a small Piece of burnt Cork, with Legs of Linen Thread, and a Grain or two of Lead stuck in1 to give him more Weight. Upon the Table, over which he hangs, we stick a Wire upright, as high as the Vial and Wire, 2 or 3 Inches2 from the Spider: then we animate him, by setting the electrified Vial, at the same Distance on the other Side of him: he will immediately fly to the Wire of the Vial, bend his Legs in touching it, then spring off and fly to the Wire in the Table; thence again to the Wire of the Vial; playing with his Legs against both in a very extraordinary3 Manner, appearing perfectly alive to Persons unacquainted. He will continue this Motion an Hour or more in dry Weather.

We electrify upon Wax, in the Dark, a Book that has a double Line of Gold round upon the Covers, and then apply a Knuckle to the Gilding; the Fire appears every where upon the Gold like a Flash of Lightning; not upon the Leather; nor if you touch the Leather instead of the Gold. We rub our Tubes with Buck Skin, and observe always to keep the same Side to the Tube, and never to sully the Tube by Handling. Thus they work readily and easily without the least Fatigue, especially if kept in tight Pastboard Cases, lined with Flannel and fitting close to the Tube.4 This I mention, because the European Papers on Electricity frequently speak of rubbing the Tube as a fatiguing Exercise. Our Spheres are fixt on Iron Axels,5 which pass thro’ them.6 At one End of the Axis there is a small Handle with which we7 turn the Sphere like a common Grind-Stone. This we find very commode;8 as the Machine takes up but little Room, is portable, and may be enclosed in a tight Box, when not in Use. ’Tis true the Sphere does not turn so swift as when the great Wheel is used; but Swiftness we think of little Importance, since a few Turns will charge the Vial &c. sufficiently.9

I must say no more of Electricity at present, or I shall not leave myself Time to answer your Favour of March last, which came to Hand by Dowers,1 with the Magazines and LeBlank’s Letters, Martin’s Electricity and Watson’s first Part and Sequel.2

We are, as we always have been, extreamly obliged to you for your kind Care in sending us, from Time to Time, what is new and curious, tho’ not wrote for.

The rest of the Letter on private Affairs and Matters relating to the Philadelphia Library.3

To Peter Collinson Esqr. F.R.S. London

[Note numbering follows the Franklin Papers source.]

1In Bowdoin MS: Letter I; in all printed editions of Exper. and Obser.: Letter II. See above, pp. 115–18, for a discussion of MS and printed versions.

2This letter has been given almost as many dates as it has had printings. It is dated Sept. 1, 1747, in the editions of 1751, 1754, and 1760; but July 11 in those of 1769 and 1774 and by the principal editors—Dubourg, Duane, Sparks, Bigelow, Smyth—of Franklin’s collected works. William Watson, who quoted part of it in “Some further Inquiries into the Nature and Properties of Electricity,” Phil. Trans., XLV (1748), 98–100, gave its date as June 1. An autograph note by BF in both his own copy of the 1751 edition and the Yale presentation copy of the same edition (both in Yale Univ. Lib.) reads: “The two first Letters transpos’d, except the Dates”—which would date this letter July 28. Franklin’s note, however, should not be taken as assigning the letter to that date; BF only recognized that the first two letters were misplaced. The date of the Bowdoin MS is the correct one. BF confirms this in a letter to Collinson, Aug. 14, where he says he had sent a long letter on electricity by the “Governor’s Ship.” This was the Greyhound, Captain Budden, which sailed from Philadelphia on June 1. I. Bernard Cohen discusses the problem fully in BF’s Experiments, p. 166, and in “Some Problems in Relation to the Dates of Benjamin Franklin’s First Letters on Electricity,” APS Proc., C (1956), 537–9.

3See above, p. 118.

4In all printed editions: “Points” is replaced by “pointed bodies.”

5In all printed editions: “it” is replaced by “the shot.”

6All printed editions add: “or if you bring it very near.”

7In all printed editions: “slide” is replaced by “sliding.”

8In 1751, 1754, and 1760 editions: “will do as well”; in 1769 and 1774 editions: “will do near as well.”

9In all printed editions: “iron” replaces “Metal.”

1All printed editions add: “for perfectly dry wood will no more conduct electricity than sealing-wax.”

2Footnote in 1769 and 1774 editions: “This power of points to throw off the electrical fire, was first communicated to me by my ingenious friend Mr. Thomas Hopkinson, since deceased, whose virtue and integrity, in every station of life, public and private, will ever make his Memory dear to those who knew him, and knew how to value him.” In the margin of his own copy of the 1751 edition BF had written Hopkinson’s name.

3Footnote in the 1769 and 1774 editions: “This was Mr. Hopkinson’s Experiment, made with an expectation of drawing a more sharp and powerful spark from the point, as from a kind of focus, and he was surprized to find little or none.” In the 1774 edition, the footnote is keyed to “bayonet.”

4In all printed editions this sentence begins with “Or.”

5All printed editions add: “or iron rod.”

6In all printed editions altered to: “the gun-barrel, or rod, cannot by applying the tube to the other end be electrised so as to give a spark.”

7All printed editions omit “is.”

9In all printed editions: “moist Breath” is replaced by “moisture.”

1In all printed editions: “it” is replaced by “the same.”

8BF’s emendation in MS: “This is since found to be by the Smoke and not the Light of the Candle. All burning Candles give more or less Smoke; this Smoke attracted, electrified and repell’d, carries off the Electricity.” Printed emendation in 1751, 1754, and 1760 editions: “From some observations since made, I am inclined to think, that it is not the light, but the smoke or non-electric effluvia from the candle, coal, and red-hot iron, that carry off the electrical fire, being first attracted and then repelled.”

2In all printed versions: “dropt on hot iron.” The words “under the Shot” are omitted from all printed editions.

3Thomas Burnet, The Sacred Theory of the Earth: containing an Account of the Original of the Earth (6th edit., 2v. London, 1726), and William Whiston, A New Theory of the Earth … Wherein the Creation … Deluge and … Conflagration as laid down in the Holy Scriptures are shown to be perfectly agreeable to reason and philosophy (5th edit., London, 1737).

4This is a marginal note in MS in another hand; it is incorporated in the 1751 and all later editions with the bracketed words, as here. The 1769 and 1774 editions also add: “or it will be apt to fail.”

5Footnote in 1769 and 1774 editions: “This different Effect probably did not arise from any difference in the light, but rather from the particles separated from the candle, being first attracted and then repelled, carrying off the electric matter with them; and from the rarefying the air, between the glowing coal or red-hot iron, and the electrised shot, through which rarified air the electric fluid could more readily pass.”

6In all printed editions: “being really an Element.”

7In his own copy of the 1751 edition BF wrote in the margin: “Philip Syng.”

8BF’s emendation in MS: “These Wheels are since found to move from no other Causes than Attraction, Electrification and Repulsion of their circumferent Parts.” Printed emendation in 1751, 1754, and 1760 editions: “We afterwards discovered, that the afflux or efflux of the electrical fire, was not the cause of the motions of those wheels, but various circumstances of attraction and repulsion.” The same information appears in a footnote in 1769 and 1774 editions, keyed to the end of the paragraph: “These experiments with the wheels were made and communicated to me by my worthy and ingenious friend Mr. Philip Syng; but we afterwards discovered that the motion of those wheels was not owing to any afflux or efflux of the electric fluid, but to various circumstances of attraction and repulsion. 1750.”

9All printed editions omit “and it were necessary.”

1William Watson, A Sequel to the Experiments and Observations Tending to illustrate the Nature and Properties of Electricity (London, 1746), pp. 31–2.

2Added in all printed editions: “with his knuckle.”

3All printed editions omit “standing.”

4In all printed editions: “the three persons.”

5In all printed editions: “approach to touch.”

6All printed editions omit “between them.”

7In all printed editions: “We say B (and bodies like circumstanced) is.”

8All printed editions omit this sentence.

9In all printed editions “it” is replaced by “that body.”

1In all printed editions: “(in his Sequel).” The page reference, left blank in MS, has been inserted by the editors.

2All printed editions insert “and.”

3In all printed editions: “just upon sailing.”

4In his own copy of the 1751 edition BF wrote Philip Syng’s name in the margin at this point.

5All printed editions omit “the Vial.”

6All printed editions omit this footnote, which appears in MS, probably in Bowdoin’s hand.

7Footnote in 1769 and 1774 editions: “By taking a spark from the wire, the electricity within the bottle is diminished; the outside of the bottle then draws some from the person holding it, and leaves him in the negative state. Then when his hand or face is touch’d, an equal quantity is restored to him from the person touching.”

8Emendation in 1751, 1754, and 1760 editions: “We soon found that it was only necessary for one of them to stand on wax.” Added in 1769 and 1774 editions: “or A on wax, and B on the floor.”

9In all printed editions: “if another gentleman and lady, C and D.”

1In all printed editions: “stuck in him.”

2In 1774 edition: 4 or 5 inches.

3In all printed editions “extraordinary” is replaced by “entertaining.”

4Footnote in 1751, 1754, and 1760 editions: “Our tubes are made here of green glass, 27 or 30 inches long, as big as can be grasped. Electricity is so much in vogue, that above one hundred of them have been sold within these four months past.” The 1769 and 1774 editions include only the first sentence of the footnote.

5In all printed editions: “axes.”

6At this point BF wrote Philip Syng’s name in the margin of his copy of the 1751 edition.

7In 1760, 1769, and 1774 editions: “we” is replaced by “you.”

8In all printed editions: “commodious.”

9Footnote in 1769 and 1774 editions: “This simple easily-made machine was a contrivance of Mr. Syng’s.” In all printed editions BF’s letter ends at this point.

1Not found. But see Collinson’s letter of June 1 (below, p. 141) for confirmatory evidence of date and contents.

2Jean Bernard LeBlanc, Letters on the English and French Nations (2v., London, 1747); Benjamin Martin, An Essay on Electricity (Bath, 1740); William Watson, Experiments and Observations Tending to illustrate the Nature and Properties of Electricity (London, 1746), and A Sequel to Experiments and Observations … (London, 1746).

3This sentence and the address are in BF’s hand.

Collinson showed BF’s report to the president and some members of the Royal Society, including William Watson. Quick to appreciate its merit, Watson quoted nearly three pages of the most important part of it—BF’s statement of the single-fluid theory (pp. 130–2 above)—in the paper he read the Society, Jan. 21, 1748. BF’s electrical experiments, made before the American could have learned about similar experiments in England, Watson declared, showed that he was “very conversant in this part of Natural Philosophy.” Phil. Trans., XLV (1748), 98–100. See also Cohen, BF’s Experiments, pp. 78–9.

Authorial notes

[The following note(s) appeared in the margins or otherwise outside the text flow in the original source, and have been moved here for purposes of the digital edition.]

º *We suppose every Particle of Sand, moist Breath9 or Smoke, being first attracted and then repelled, carries off with it its Portion of the Electrical Fire, but that it1 still subsists in those Particles, till they communicate it to something else, and that it is never really destroyed. So when Water is thrown on common Fire, we do not imagine the Element is thereby destroy’d or annihilated, but only dispersed; each Particle of Water carrying off in Vapour its Portion of the Fire which it had attracted and attacht to itself.

º *The person standing on wax, holding the electrised bottle, when you touch the Hook of the bottle and receive a Spark from it, is electrified minus; a Quantity of electrical fire going out of him into the Coating of the bottle, equal to the Quantity taken from the Hook: in this state a person on the Floor touching him, will give him the quantity he has lost.6

Index Entries