Benjamin Franklin Papers

To Benjamin Franklin from John Ewing, 4 January 1770

From John Ewing3

ALS: American Philosophical Society

Philada. Janry. 4th 17694


Our Philosophical Society have at Length ordered me to draw out an Account of our Observations of the Transits of Venus and Mercury to be transmitted to you as our President thro’ whose Hands we think they may most conveniently be communicated to the learned Societies of Europe to whom you may apprehend they will be agreable. The Reason of their not coming sooner to Hand was a rash Agreement of the Society not to send them abroad untill we had printed them in our own Transactions.5 But finding that there was some Reason to suspect that some partial Accounts of them had been transmitted to England, by some of our Members privately, which possibly might be inaccurate and not much to be depended on, the Society have thought proper to reconsider that hasty Agreement, and send them without farther Loss of Time. We hope however that they will be as soon with you as those that have been made in South America and the East Indies. I have accordingly enclosed to you two Copies, one directed to the Astronomer Royal Mr. Maskelyne at Greenwich6 and the other to be transmitted by you to any of the learned Societies of Europe you shall think proper.7 I would have had them transcribed in a fairer Hand than my own, but only that the only Post which can reach the Packet leaves Town this morning.

You are well acquainted, Sir, with the Serenity of our Air, and the Advantages we enjoy above many other Countries in Europe for making celestial Observations could a fixed Observatory be established in Philadelphia. I have mentioned this Matter to Mr. Maskelyne and referred him to you for Advice how to bring it into Execution should it meet with your Approbation. You are well acquainted with the Views of our Assembly, and the Unreasonableness of expecting that they would lay out any of the public Money for such a Purpose, unless it was recommended by you to them, as they place an unreserved Confidence in your Judgment, concerning what Measures would Lend to the Reputation of the Province the Advancement of useful Knowledge and the Benefit of the public in general. Geography, Navigation and the Arts that depend upon them are daily reaping Advantages from the Astronomical Observations made in the different Observatories of Europe. Should you think it of any Consequence that we in this infant Country might bear any Part in these Things, your known Character and Abilities to judge in these Matters must necessarily have so much Influence with our Assembly as to induce them to bear at least a Part in the Expences of it. And possibly Mr. Maskelyne might suggest some Means of affording some Assistance from Home, from the Consideration of its being made subservient to his Observatory at Greenwich and put under his general Direction.8

I have not mentioned this Proposal to any Persons here but to Mr. Coomb, excepting to you, and that under a Promise that he will not speak of it, as I apprehend that there is a Propriety in its coming from you and the Astronomer Royal. So that if it does not meet with your Approbation, pray let it sleep and be so kind as to excuse the Trouble given you by Sir Your most obedient and very humble Servant

John Ewing

P S. Mr. Coombe tells me that he has mentioned the above Proposal to his Son, with a Desire that he should speak to you on the Subject.9

Please to send me Authentic Accounts of the Observations of the Transit of Venus made in as many Places as you can conveniently procure, if your Leisure from more important Business will permit it, that we may here also endeavour to solve the curious Problem of the Suns Parallax. If it would not be trespassing too much, I should also be much obliged to you for an Account of Messrs. Mason’s & Dixons Determinations of the Length of a Degree of Latitude here, as they have been employed by the R. Society to measure it in the lower Counties.1

Endorsed: Revd Mr Ewing  Jan 4. 1770

[Note numbering follows the Franklin Papers source.]

3Pastor of the First Presbyterian Church in Philadelphia, and one of the group that had observed the transit of Venus from the Statehouse yard. See above, XI, 526 n; XVI, 241–2.

4[BF’s note:] should be 1770.

5See ibid., p. 241.

6The Astronomer Royal had already received the “partial Accounts” and found them unsatisfactory; ibid., pp. 257, 269–70.

7BF forwarded the observations to Jean-Baptiste LeRoy, who transmitted them to the Académie royale des sciences. See BF to LeRoy below, Oct. 2, and Alexandre Pingré, “Examen critique des observations du passage de Vénus sur le disque du soleil, le 3 juin 1769; et des conséquences qu’on peut légitimement en tirer,” Histoire de l’Académie royale des sciences …, LXXII (1770), 578–9.

8Ewing returned to this idea in a letter to BF below, June 14; see also BF to Ewing below, Aug. 27, and Brooke Hindle, The Pursuit of Science in Revolutionary America, 1735–1789 (Chapel Hill, [1956]), pp. 167–8.

9For Thomas Coombe, Sr., BF’s old friend, see above, XI, 107 n; XVI, 112. His son, Thomas Jr., had gone to England in 1768 to seek ordination, and did not return to America until 1772. The young man’s letters to his father, in the Hist. Soc. of Pa., indicate that he saw a good deal of BF during his stay; see also above, XV, 286, 293.

1The hope of determining the sun’s parallax, as mentioned in Vol. XVI, was what interested the scientific world in the transit of Venus. For the involvement of the Royal Society in the Mason and Dixon survey see above, XII, 341–2.

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