From Benjamin Franklin to Mary Stevenson, 30 March 1761
To Mary Stevenson
ALS: Yale University Library
Cravenstreet, Monday March 30. 1761
My dear Friend
As you have been so good as to forgive my long Delay of writing to you and answering your always agreable Letters,4 I shall not now trouble you with the Apology I had written on that head in one of my Pieces of Letters never finish’d.
Supposing the Fact, that the Water of the Well at Bristol is warmer after some time pumping, I think your manner of accounting for that increas’d Warmth very ingenious and probable.5 It did not occur to me, and therefore I doubted of the Fact.
You are, I think, quite right in your Opinion, that the Rising of the Tides in Rivers is not owing to the immediate Influence of the Moon on the Rivers.6 It is rather a subsequent Effect of the Influence of the Moon on the Sea, and does not make its Appearance in some Rivers till the Moon has long pass’d by. I have not express’d myself clearly if you have understood me to mean otherwise. You know I have mention’d it as a Fact, that there are in some Rivers several Tides all existing at the same time; that is, two, three, or more, Highwaters, and as many Low-Waters, in different Parts of the same River, which cannot possibly be all Effects of the Moon’s immediate Action on that River; but they may be subsequent Effects of her Action on the Sea.
In the enclos’d Paper you will find my Sentiments on several Points relating to the Air and the Evaporation of Water.7 It is Mr. Collinson’s Copy, who took it from one I sent thro’ his Hands to a Correspondent in France some Years since; I have, as he desired me, corrected the Mistakes he made in transcribing, and must return it to him; but if you think it worth while, you may take a Copy of it: I would have sav’d you any trouble of that kind, but had not time.
Some day in the next or the following Week, I purpose to have the pleasure of seeing you at Wanstead;8 I shall accompany your good Mama there, and stay till the next Morning, if it may be done without incommoding your Family too much. We may then discourse any Points in this Paper that do not seem clear to you; and taking a Walk to some of Lord Tilney’s Ponds,9 make a few Experiments there to explain the Nature of the Tides more fully. In the mean time, believe me to be, with the highest Esteem and Regard, my dear good Girl, your sincerely affectionate Friend
B Franklin
My very respectful Compliments to good Mrs. Tickel, and to Mrs. Rooke and Miss Pit.1 If the above propos’d Visit should not be convenient let me know by a Line when it may be more suitable.
Miss Stevenson
4. Apparently BF had not written Polly since November 1760; see above, pp. 247–52.
5. See above, pp. 217–18, for Polly’s speculations about the causes of this phenomenon.
6. See above, pp. 195, 213–18, for an exchange of letters between BF and Polly about tides in rivers.
7. In a letter of Jan. 13, 1761, Polly appealed to her “indulgent Preceptor” to explain evaporation; see above, pp. 269–70. The paper BF now sent her cannot be certainly identified, but it may well have been his letter to John Perkins, Feb. 4, 1753, on waterspouts (above, IV, 429–42), or the paper entitled “Physical and Meteorological Observations, Conjectures and Suppositions” (1751?), read to the Royal Society Dec. 23, 1756 (above, IV, 235–43). The letter on waterspouts seems the more likely because Polly discussed it and Perkins’ reply in her letter to BF of April 27, 1761, below, p. 308.
8. A village about ten miles from London where Polly spent much of her time attending to two elderly aunts, Mrs. Tickell and Mrs. Rooke.
9. John Tylney, Earl Tylney of Castlemaine (1712–1784), F.R.S., 1746. His grandfather, Sir Josiah Child (1630–1699), writer of a popular treatise on trade and governor of the East India Company, 1681–3, 1686–8, had purchased Wanstead Abbey in 1673 and had spent “prodigious” sums in planting “walnut-trees about his seate, and making fish-ponds, many miles in circuit.” DNB; G. E. Cockayne, ed., The Complete Peerage, III (London, 1913), 92.
1. Miss Pitt was a friend of Polly’s; she went to Jamaica in 1763.