Benjamin Franklin Papers
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From Benjamin Franklin to John Winthrop, 2 July 1768

To John Winthrop

Reprinted from William Temple Franklin, ed., Memoirs of the Life and Writings of Benjamin Franklin, LL.D., F.R.S., &c. (quarto edition, 3 vols., London, 1817–18), III, 370–4.

London, July 2, 1768.

Dear Sir,

You must needs think the time long that your instruments have been in hand. Sundry circumstances have occasioned the delay. Mr. Short, 9 who undertook to make the telescope, was long in a bad state of health, and much in the country for the benefit of the air. He however at length finished the material parts that required his own hand, and waited only for something about the mounting that was to have been done by another workman; when he was removed by death. I have put in my claim to the instrument, and shall obtain it from the executors as soon as his affairs can be settled. It is now become much more valuable than it would have been if he had lived, as he excelled all others in that branch. The price agreed for was £100.

The equal altitudes and transit instrument was undertaken by Mr. Bird, who doing all his work with his own hands for the sake of greater truth and exactness, one must have patience that expects any thing from him. He is so singularly eminent in his way, that the commissioners of longitude have lately given him £500 merely to discover and make public his method of dividing instruments.1 I send it you herewith. But what has made him longer in producing your instrument is, the great and hasty demand on him from France and Russia, and our society here for instruments to go to different parts of the world for observing the next transit of Venus; some to be used in Siberia, some for the observers that go to the South Seas, some for those that go to Hudson’s Bay.2 These are now all completed and mostly gone, it being necessary on account of the distance, that they should go this year to be ready on the spot in time. And now he tells me he can finish yours, and that I shall have it next week. Possibly he may keep his word. But we are not to wonder if he does not.

Mr. Martin, when I called to see his panopticon, had not one ready;3 but was to let me know when he should have one to show me. I have not since heard from him, but will call again.

Mr. Maskelyne wishes much that some of the governments in North America would send an astronomer to Lake Superior to observe this transit. I know no one of them likely to have a spirit for such an undertaking, unless it be the Massachusetts, or that have a person and instruments suitable. He presents you one of his pamphlets, which I now send you, together with two letters from him to me, relating to that observation. If your health and strength were sufficient for such an expedition, I should be glad to hear you had undertaken it.4 Possibly you may have an élève that is capable. The fitting you out to observe the former transit, was a public act for the benefit of science that did your province great honor.5

We expect soon a new volume of the transactions, in which your piece will be printed. I have not yet got the separate ones which I ordered.6

It is perhaps not so extraordinary that unlearned men, such as commonly compose our church vestries, should not yet be acquainted with, and sensible of the benefit of metal conductors, in averting the stroke of lightning, and preserving our houses from its violent effects; or that they should be still prejudiced against the use of such conductors, when we see how long even philosophers, men of extensive science and great ingenuity, can hold out against the evidence of new knowledge that does not square with their preconceptions, and how long men can retain a practice that is conformable to their prejudices, and expect a benefit from such practice, though constant experience shows its inutility. A late piece of the Abbé Nollet, printed last year in the Memoirs of the French Academy of Sciences, 7 affords strong instances of this; for though the very relations he gives of the effects of lightning in several churches and other buildings, shows clearly that it was conducted from one part to another by wires, gildings, or other pieces of metal that were within, or connected with the building; yet in the same paper he objects to the providing metalline conductors without the building, as useless or dangerous.8 He cautions people not to ring the church bells during a thunder storm, lest the lightning in its way to the earth should be conducted down to them by the bell-ropes, 9 which are but bad conductors; and yet is against fixing rods on the outside of the steeple, which are known to be much better conductors, and which it would certainly choose to pass in, rather than in dry hemp. And though for a thousand years past bells have been consecrated by priests of the Romish church, 1 in expectation that the sound of such blessed bells would drive away those storms, and secure our buildings from the stroke of lightning; and during so long a period it has not been found by experience that places within the reach of such blessed sound are safer than others where it is never heard; but that on the contrary, the lightning seems to strike steeples of choice, and that at the very time the bells are ringing;2 yet still they continue to bless the new bells and jangle the old ones whenever it thunders. One would think it was now time to try some other trick; and ours is recommended, (nothwithstanding what this able philosopher says, ) by more than twelve years’ experience, wherein, among the great number of houses furnished with iron rods in North America, not one so guarded has been materially hurt with lightning, several have been evidently preserved by their means; while a number of houses, churches, barns, ships, &c. in different places, unprovided with rods, have been struck and greatly damaged, demolished or burnt. Probably the vestries of our English churches are not well acquainted with these facts; otherwise, since as protestants, they have no faith in the blessing of bells, they would be less excusable in not providing this other security for their respective churches, (more exposed than common buildings by their greater height, ) and for the good people that may happen to be assembled in them during a tempest.

I have nothing new in the philosophical way to communicate to you, unless what follows may be such. When I was last year in Germany, I met with a glass, being a tube about eight inches long, half an inch in diameter, with a hollow ball of near an inch diameter at one end, and one of near an inch and a half at the other, hermetically sealed, and half filled with water.3 If one end is held in the hand, and the other a little elevated above the level, a constant succession of large bubbles proceeds from the end in the hand to the other hand, and make an appearance that puzzled me much, till I found that the space not filled with water was also free from air; and either filled with a subtil invisible vapor continually rising from the water, and extremely rarefiable by the least heat at one end, and condensable again by the least cold at the other; or it is the very fluid of fire itself, which parting from the hand, pervades the glass, and by its expansive force depresses the water till it can pass between it and the glass, and escape to the other end, where it gets through the glass again into the air. I am rather inclined to the first opinion, but doubtful between the two. An ingenious artist here, Mr. Nairne, has made a number of them from mine, and improved them; for his are much more sensible4 than those I brought from Germany. I bored a very small hole through the wainscot in the seat of my window, through which a little cold air constantly entered, while the air in the room was kept warmer by fires daily made in it, being winter time. I placed one of his glasses with the elevated end against this hole, and the bubbles from the other end, which was in a warmer situation, were continually passing day and night, to the no small surprise of philosophical spectators. Each bubble discharged is larger than that from which it proceeds, and yet that is not diminished; and by adding itself to the bubble at the other end, that bubble is not increased, which seems very paradoxical. When the balls at each end are made large, and the connecting tube very small and bent at right angles, so that the balls, instead of being at the ends, may be brought on the side of the tube, and the tube is held so as that the balls are above it, the water will be depressed in that which is held in the hand, and rise in the other as a jet or fountain; when it is all in the other it begins to boil, as it were, by the vapor passing up through it; and the instant it begins to boil a sudden coldness is felt in the ball held; a curious experiment first observed and shown me by Mr. Nairne, similar to the old observation, I think of Aristotle, that the bottom of the boiling pot is not warm;5 and may help to explain that fact, if indeed it is a fact. When the water stands at an equal height in both these balls, and all is at rest, if you wet one of the balls by means of a feather dipped in spirit, though the spirit is of the same temperament as to heat and cold as the water in the glass, yet the cold occasioned by the evaporation of the spirit from the wetted ball will so condense the vapor over the water contained in that ball, as that the water of the other ball will be pressed up into it, followed by a succession of bubbles, till the spirit is all dried away. I think the observations on these little instruments may suggest and be applied to some beneficial uses. It has been thought that water reduced to vapor by heat, was rarefied only 14, 000 times, and on this principle our engines for raising water by fire are said to be constructed; but if the vapor so much rarefied from water is capable of being itself still farther rarefied to a boundless degree by the application of heat to the vessels, or parts of vessels, containing the vapor, (as at first it is applied to those containing the water, ) perhaps a much greater power may be obtained with little additional expense. I think, too, that the power of easily moving water from one end to the other of a moveable beam, suspended in the middle6 by a small degree of heat, may be applied advantageously to some other mechanical purposes.

The magic square and circle, I am told, have occasioned a good deal of puzzling among the mathematicians here, but no one has desired me to show him my method of disposing the numbers.7 It seems they wish rather to investigate it themselves. When I have the pleasure of seeing you I will communicate it. With singular esteem and respect, I am, dear sir, your most obedient humble servant,

B. Franklin.

[Note numbering follows the Franklin Papers source.]

9For James Short, F.R.S., London mathematician and instrument-maker, see above, V, 232; X, 137 n. The instruments have not been mentioned in the earlier extant correspondence between BF and Winthrop.

1John Bird, The Method of Dividing Astronomical Instruments (London, 1767). For the author see above, III, 484 n; and for the commissioners of longitude VII, 208–10. The instrument was completed in the early autumn at a cost of £42. Journal, Sept. 25, 1768.

2See Harry Woolf, The Transits of Venus, a Study in Eighteenth-Century American Science (Princeton, 1959), pp. 170–2.

3For Benjamin Martin, mathematician and instrument-maker, see above, XIV, 4 n. The New English Dictionary, citing this letter, defines a panopticon as “apparently a kind of telescope.” Webster’s New International Dictionary, 2nd ed., defines the word with equal but different imprecision as “a kind of optical instrument, as a combination of a telescope and microscope.” The editors will not rush in where lexicographers fear to tread.

4For Nevil Maskelyne (1732–1811), the Astronomer Royal, see DNB; the pamphlet that he sent Winthrop via BF was probably Instructions Relative to the Observation of the Ensuing Transit of the Planet Venus (London, 1768). Ill health, as BF supposed, prevented Winthrop from observing the transit himself. But he quoted this paragraph of BF’s letter to his friend James Bowdoin, a leading member of the governor’s council in Massachusetts, and added his own arguments to persuade that colony to carry out Maskelyne’s suggestion; after long correspondence, however, the enterprise was abandoned. Mass. Hist. Soc. Collections, 6th series, IX (1897), 116–19.

5At the time of the earlier transit of Venus, in 1761, Harvard College had sent an expedition under Winthrop to St. John’s, Newfoundland, to study particularly the parallax of the sun. The impetus behind the expeditions to observe the two transits, in 1761 and 1769, was the hope of determining the parallax, and thereby establishing the mean distance between the earth and the sun.

6Winthrop’s Cogita de Cometis was published in Latin in Phil. Trans., LVII, pt. I (1767), 132–54, and reprinted anonymously as Cogitata de Cometis. Communicated by Benjamin Franklin LL.D. F.R.S. (London, 1767). The date of this separate edition, as BF’s letter implies, should also be 1768. He ordered it from W. Bowyer & Co., the printer for the Royal Society; their bill in the APS is dated May 17 and receipted July 28, 1768. The remainder of the letter, except for the final paragraph, was printed in Exper. and Obser., 1769 edit., pp. 486–92. There are slight verbal differences between this early version and the text in WTF, Memoirs; but in only one case, noted below, is the sense affected.

7Jean-Antoine Nollet, “Memoire sur les effets de tonnere comparés à ceux de l’électricité; avec quelques considerations sur les moyens de se garantir des premiers,” Histoire de l’Académie royale des sciences for 1764 (Paris, 1767), pp. 408–51. For Nollet, BF’s perennial opponent on electrical matters, see above, IV, 423. In the extract in Exper. and Obser. BF appended passages in French from Nollet’s article; these have been translated, paraphrased, and condensed in notes below.

8[Paraphrase of Nollet:] Research on thunder and its effects is laudable, but what is more important is finding a means of protection. The great discovery [of lightning rods] has not, after twelve years of testing, fulfilled the promises made for it. I said a long time ago that these iron points in the air attract the fire of thunder, and I still say that drawing the charge of fire from a storm cloud is not the function of a physicist.

9[Paraphrase of Nollet:] Bells, by virtue of being blessed, should drive away lightning; but the Church allows human wisdom to determine when to use this protection. I do not know whether sound can physically burst a cloud and make it discharge its fire, but experience proves that thunder can strike a steeple whether or not the bells are ringing. If they are, the bellringers are in great danger, because they hold the ropes by which the lightning can reach them. It is wiser to leave the bells silent when a storm is overhead.

1[Paraphrase of Nollet:] According to the ritual of Paris for blessing the bells, God is besought to drive away at their sound a number of evils, including those from tempest, thunder, and lightning.

2[Paraphrase of Nollet:] In one night in 1718 lightning hit twenty-four churches in Brittany in which the bells were ringing, and spared all others; in one that was struck two of the four bellringers were killed.

3A pulse glass, designed to show the boiling of liquids at low temperature. The glass is partially filled with water, ether, or alcohol, which is boiled to reduce the air before the contents are sealed.

4Sensitive. For Edward Nairne, electrician and instrument-maker, see above, X, 171 n.

5See William D. Ross, gen. ed., The Works of Aristotle Translated into English (12 vols., Oxford, 1908–52), VII, book XXIV, problem 5.

6The extract in Exper. and Obser. adds here: “like a scale beam.” In a letter from BF to Polly Stevenson below, July 20, 1768, two drawings appear. One is the pulse-glass mechanism on a scale beam, and the other has two pulse glasses on a large wheel.

7See above, IV, 392–403.

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