From [Joseph Priestley]
ALS (mutilated):8 American Philosophical Society
Warrington 25 March 1766.
I have received your letter, containing some remarks on my experiments, and a printed paper for the transactions which has given me very great satisfaction, and for which I think myself much obliged to you.9 I shall think myself very happy if the accounts you are pleased to permit me to send you of my imperfect experiments do but revive your attention to your once favourite study; for that seems to be universally acknowledged to be the great desideration to further discoveries.
Immediately upon the receipt of yours, I set about pursuing the hints you gave me, and I am impatient, little as I have done, to give you an account of it. My great ambition would be to act under your auspices in the business of electricity.
I carefully repeated the experiment with condensed air and could perceive no more cloudiness when it could not be excited than when it could, as I have written more at large to Dr. Watson, to whom I beg leave to refer you.1
I have this day tried the experiment with the vanes, and I believe I should have done it; tho not so soon, if You had not recommended it to me. I took a cork, and stuck into the sides of it (pointing directly from the center) thirteen vanes each consisting of half a common card. Into the middle of the cork I stuck a needle, by which I suspended [passage missing] glass stand, in contact with a pointed wire projecting some inches from the jar. In this situation it is evident, that for every spark that I took from the inside, one must enter at the point which communicated with the outside. I then held the vanes about two or three inches from the point of the wire, but a little on one side, that the streams of air (if there were any) might act to advantage, on the extremities of them; and observed, that all the time I was taking sparks from the wire communicating with the inside, the vanes turned, as if strongly blown upon by a current setting from the point. In a great number of trials they never failed to turn the same way, and even if they were made to turn as much as possible the contrary way, the stream never failed to fetch them back again, and make them turn as before.
To determine whether this effect was produced by any electrical attraction or repulsion, I placed a wire communicating with the ground, between the vanes and the point, to intercept the electricity, but the vanes turned as swiftly as before. The motion was sometimes so swift, that I could hardly distinguish the separate vanes as they turned round, and the motion would continue a very considerable time.
As I never chuse to depend upon my own testimony, I called in Mr. Holt2 to witness the experiments, and we repeat[ed passage missing] different principles, and very agreeable to the theory of negative and positive electricity.3
I shall make all the experiments you direct, and many more which I have thought of relating to mephitic air4 when my apparatus is completed, and I have finished the greatest part of my treatise on Electricity. I have sent to Mr. Price five numbers, a quire each, and I shall send (if all be well) three more the beginning of the next week. You must only consider it as a very rough draught, but I think I have made the most of the materials I have at present. I am impatient to receive the books you are so kind as to procure for me, and wish you could likewise procure me the histoire de l’electricité you mention.5 Desire Mr. Canton also to favour me with his Gilbert, and that piece of Otto Gueric, if he have it, which treats of electricity.6 Please also to desire Mr. Johnson to send me a copy of Theophrastus for I have not the book, tho’ I remember reading it formerly, I think, in an edition of Dr. Hill’s.7 I have this day been favoured with [a] letter from Mr. Price, for which I beg you would make my acknowledgments to him. After puzling myself to no purpose with some of Mr. Wilson’s experiments, you will find that I have related them just as he published them himself, with very few remarks.8 I thought that the most [about five words missing] directed by you what to do [remainder missing]
Addressed: To / Doctor Franklin / at Mrs Stephens’s, Craven-street, / in the Strand / London.
8. The bottom of the folio has been cut off, causing the loss of one or more lines on each of the first two pages and the concluding lines and signature on the third.
9. BF’s letter has not been found and the “printed paper for the transactions” has not been identified.
1. Schofield does not print the letter to Watson mentioned here.
2. John Holt (d. 1772), a fellow tutor at Warrington Academy.
3. For BF’s introduction in 1747 of this terminology and the basic concept it represents, see above, III, 130–2, 157–8, 162–3.
4. Carbon dioxide.
5. Probably Abbé de Mangin’s Histoire générale et particulière de I’électricité (3 vols., Paris, 1752). Possibly, however, Priestley may have intended the Histoire abrégée that Thomas-Francois Dalibard prefixed to his translation of BF’s Exper. and Obser. in both the 1752 and 1756 editions; above, IV, 302, 425.
6. William Gilbert, De Magnete Magneticisque Corporibus (London, 1760), and Otto Guericke, Experimenta Nova Magdeburgica (Amsterdam, 1672).
7. John Hill, Theophrastus’s History of Stones with an English Translation and Critical and Philosophical Notes (London, 1746).
8. Dr. [Benjamin] Hoadly and Mr. [Benjamin] Wilson, Observations on a Series of Electrical Experiments (London, 1756). For BF’s comments on this pamphlet, see above, VIII, 239–63.