Benjamin Franklin Papers

To Benjamin Franklin from John Winthrop, 29 September 1762

From John Winthrop

MS not found; reprinted from Benjamin Franklin, Experiments and Observations on Electricity (London, 1769), p. 434.6

Cambridge, N.E. Sept. 29, 1762.


There is an observation relating to electricity in the atmosphere, which seemed new to me, though perhaps it will not to you: However, I will venture to mention it. I have some points on the top of my house, and the wire where it passes within-side the house is furnished with bells, according to your method, to give notice of the passage of the electric fluid.7 In summer, these bells generally ring at the approach of a thunder cloud; but cease soon after it begins to rain. In winter, they sometimes, though not very often, ring while it is snowing; but never, that I remember, when it rains. But what was unexpected to me was, that, though the bells had not rung while it was snowing, yet the next day, after it had done snowing, and the weather was cleared up; while the snow was driven about by a high wind at W. or N.W. the bells rung for several hours (though with little intermissions) as briskly as ever I knew them, and I drew considerable sparks from the wire. This phaenomenon I never observed but twice; viz. on the 31st of January, 1760, and the 3d of March, 1762. I am, Sir, &c.

[Note numbering follows the Franklin Papers source.]

6Printed as Letter XLIII in Exper. and Obser., 1769 edition, and also in 1774 edition, p. 444.

7In September 1753 BF wrote Collinson (above, V, 69) that a year earlier he had “erected an Iron Rod to draw the Lightning down into my House, in order to make some Experiments on it, with two Bells to give Notice when the Rod should be electrified.” That letter was published in Exper. and Obser., 1754 edit., and Winthrop probably read it there. For DF’s uneasiness about the ringing of the bells in her house, see above, VIII, 94.

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