Benjamin Franklin Papers

From Benjamin Franklin to [Gaspard-Bonaventure-Timothée Ferry], 14 June 1783

To [Gaspard-Bonaventure-Timothée Ferry]6

AL (draft) and copy:7 Library of Congress

Passy June 14th, 1783


I received some time since the Letter you honour’d me with, containing your Hypothesis for explaining the Shock given by the electric Bottle, on which you seem to desire my Opinion. It is many Years since I was engag’d in those pleasing Studies, and my Mind is at present too much occupied with other and more important Affairs to permit my returning to them.— I cannot therefore examine your ingenious Hypothesis with the Attention it appears to merit.— You will find in a Letter of mine to Dr. Lining dated March 18. 1755,8 that I abandoned my Hypothesis of the greater Density of Glass in the Middle than near its Surfaces, as contributing to produce the Effect; because I found the Effect to be the same after I had ground that part away. And I think you might likewise try yours by an easy Experiment. Take a Plate of Lead 12 Inches square, cover one of its sides with a Coat of Bees Wax about one Line thick; upon that apply closely a thin Plate of Lead 8 Inches square, so as to leave a Margin of two Inches all round.— Electrify this Composition of Lead & Wax, and try if you can receive a Shock from it; if not, you may draw from thence a farther Argument to support your Hypothesis, because the Wax tho’ a Non Conductor is not elastic, any more than pure Lead. I see you are endow’d with a Genius for the Study of Nature and I would recommend it to you to employ your time rather in making Experiments than in making Hypotheses & forming imaginary Systems, which we are all too apt to please ourselves with till some Experiment comes, & unluckily destroys them.— Wishing you Success in your Enquiries, I have the Honour to be, Sir,9

[Note numbering follows the Franklin Papers source.]

6In answer to Ferry’s 18-page treatise of March 28: XXXIX, 402–4. On June 8 the man who had delivered it, M. Parraud, wrote from Paris to remind BF of his promise to answer, advising him to address his response to the abbé Baudet, chez the comte de Vergennes; they would take care of forwarding it to Marseille. APS.

7The copy is in the hand of Josiah Flagg and was therefore made in 1786: XXXVII, 291n.

8Published in Exper. and Obser. (1769). The section to which BF refers is the fourth paragraph; for that text see V, 522–3, where we refer to the present letter as addressed to an unknown recipient.

9Ferry answered on Oct. 12. Calling BF one of the most sublime geniuses the universe had ever produced and thanking him effusively, he enclosed a verse of his own composition, a prize-winning poem in praise of BF that was published in the Sept. 6 issue of the Jour. de Provence. Finally, he mentions that he performed the experiment BF suggested and it seems to confirm his hypothesis; not wanting to impose on BF’s time, he will not report any details. APS.

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