Benjamin Franklin Papers

To Benjamin Franklin from Joseph Priestley, 1 November 1768

From Joseph Priestley

ALS: American Philosophical Society

Leeds 1 Nov 1768.

[Dear Sir]

I take the opportunity of giving you [my letter by?] Mr. Lee of Lincoln’s inn, 1 a very worthy [and s]ensible man, a friend of mine, who wishes to be introduced to you. If you will please to deliver to him the plates belonging to your last work, 2 he will have many opportunities of transmitting them to me.

I can hardly say that I have begun to make any experiments, having been busy in fitting up a battery or two; but I have one observation, which confirms another that has often puzzled me; and is mentioned in the account of my experiments published in the history of electricity. I was amusing myself with making a pretty large common jar explode between two brass balls, fixed at as great a distance as I could make the jar to discharge; when, after several explosions, it broke (a hole being made thro it as usual) tho the Spark between the balls was of precisely the same length, and, to all appearance, in every other respect the same that it would have been, if no other communication had been made between the inside and outside of the glass. The fact mentioned in the history is, that a silver wire [was the most that]3 the battery I was using could melt, [yet was dispersed] at the same time that two of the [jars were bro]ken. In this case, though there are several [channels?] opened for the fluid, its whole force seem[s to have] been exerted in each of them. If your [torn] business will now admit of your giving me your thoughts on this subject, you would oblige me by your observations on it. In the mean time I shall be contriving a few experiments to illustrate it. I also propose to make a few to refute what Mr. L’Epinasse has advanced in the last volume of Transactions, concerning the great loss of force occasioned by interruptions in the electric circuit.4 I remember his telling me, when I was with him in London, that he did not doubt, but he could do as much by his three jars, each of which was but about a square foot, as I could with my batteries, tho’ he had only screwed their wires into one common conductor. I shall also soon draw up another paper of original experiments, for the Royal Society.5 They are those I have mentioned to you, but I must repeat some of them, with a little variation of circumstances. I am, with the greatest respect Dear Sir yours sincerely

J Priestley

Addressed: To/ Doctor Franklin / at Mrs Stephens in Craven Street / in the Strand / London / By favour of / John Lee Esqr

1John Lee, lawyer and politician, who was subsequently solicitor general and attorney general; he was known at the bar as “honest Jack Lee.” DNB.

2Probably proof sheets of the plates illustrating Exper. and Obser. ([4th ed., ] London, 1769); see BF to DF below, Dec. 21, 1768, postscript.

3These and the following brackets in the sentence, which are restorations of a corner torn off the MS, are conjectural. Priestley, however, is here paraphrasing an experiment described in his The History and Present State of Electricity (London, 1767), pp. 645–6; the words he used there can be supplied with some confidence, although the original experiment involved three jars rather than two.

4For Charles L’Epinasse see BF to Beccaria above, Sept. 21, 1768. The paper that Priestley intended to refute is in Phil. Trans., LVII (1767), 186–91.

5Probably that enclosed in Priestley to BF below, Nov. 28, 1768.

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