Benjamin Franklin Papers

From Benjamin Franklin to Thomas Hubbard, 28 April 1758

To Thomas Hubbard8

Copy: Harvard College Library

London April 28th. 1758


In persuance of Mr. Winthrop’s9 memorandum, which I lately rece’d from you, thro’ the hands of Mr. Mico,1 I have procured and delivered to him the following things, viz.

A Mahogany Case lined with lead containing 35 Square Glass Bottles, in 5 Rows, 7 in a Row.2

A Glass Globe of the same Size and kind with that I used at Philadelphia and Mounted in the same manner.

A large Glass Cylinder mounted on an Iron Axis with brass Caps, this form being most used here and thought better than the Globe as a long narrow Cushion will Electrify a greater surface at the same time.

The Bottles have Necks, which I think better then to be quite open, for so they would either be exposed to the dust and damp of the Air, if they had no Stoppers or the Stoppers would be too near together to admit of electrifying a single Bottle, or Row of Bottles, there is only a little more deficulty in lining the Inside with Tinfoil, but that is chiefly got over, by cutting it into narrow Stripes, and guiding them in with a Stick flatt at one end to apply the more conveniently, the pasted side to the Glass; I would have coated them myself if the time had not been too short; I send the Tinfoyl which I got made of a proper breadth for the purpose. They should be coated nine Inches high which brings the Coating just even with the edge of the Case, the Tinfoyl is 10 Inches broad, which allows for lapping over the bottom.

I have bored the holes in all the Stoppers for the communicating Wires, provided all the Wires, and fixed one or two to show the manner, Each Wire to go into a Bottle, is bent so that the two ends go in and spring against the Inside Coating or Lining. The middle of the Wire goes up into the Stopper with an Eye, thro’ which the long communicating Wires pass that connect all the Bottles in one Row.

To form occasional Communications with more Rowes, there must be on the long Wires of the 2nd. and 4th. Rows, four other moveable Wires, which I call Cross Wires about 2½ Inches long with a small Ball of any Metal about the size of a Pistol Bullet at each end, the Ball of one end to have a hole thro’ the middle, so that it may be slipt on the long wire, and one of these Cross Wires is to be placed between the 3d. and 4th. Bottles of the Row at each end, and on each of the above mention’d Rows, that is, two to each Row, they must be made to turn easy on the Wires so that when you would charge only the middle Rowe, you turn two of them back on the first, and two on the fifth Rows, then the middle Row will be unconnected with the others, when you would charge more Rows you turn them forwards or backwards so as to have the communication compleated with just the number of Rows you want.

The Brass handles of the Case communicate with the outside of the Bottles when you want to make the Electrical Circuit.3

I see now I have wrote it, that the greatest part of this Letter, would have been more properly addressed to Mr. Winthrop himself, but probably you will send it him with the things, and that will answer the end. Be pleased to tender my best Respects to him and the rest of the Gentlemen of the College. I am with great Esteem and Regard Sir Your most obedient humble Servant

B. Franklin

P. S. I beg the College will do me the favour to accept a Virgil I send in the Case, thought to be the most curiously printed of any Book hitherto done in the World.4

To Thomas Hubbard Esqr Boston

Endorsed: From B. Franklin Esqr April 28th. 1758 Dr. 70

[Note numbering follows the Franklin Papers source.]

8Thomas Hubbard (1702–1773), Boston merchant, speaker of the Mass. House of Representatives, 1750–59, and treasurer of Harvard College. Sibley’s Harvard Graduates, VI, 490–5. See above, VII, 69–71, for his father’s belated romance.

9On John Winthrop, professor of mathematics and natural philosophy; see above, IV, 261 n, and VI, 404 n.

1Joseph Mico, merchant and London agent for Harvard College. He wrote Hubbard, May 13, 1758, that he had given Winthrop’s memorandum to BF, and that he had sent the “Electrifying Instruments” (for which he had paid £10 3s. 7d.), together with some Hebrew psalters and this letter. Col. Soc. Mass. Pubis., X (1906), 234.

2A “battery” of Leyden jars, similar to the one described here and once owned by BF, is at APS and is pictured in I. Bernard Cohen, Franklin and Newton (Phila., 1956), following p. 454. See earlier volumes of this series for BF’s electrical experiments with globes and cylinders.

3That BF should take such obvious pleasure in writing a letter about electrical apparatus the day after the climactic hearing on the Smith appeal is another illustration of the continued variety of his interest.

4Publii Virgilii Maronis Bucolica, Georgica, et Aeneis. Birminghamiae: Typis Johannis Baskerville. MDCCLVII. This is the first important publication by the new type-designer John Baskerville (1706–1775), usually regarded as one of his finest productions. Never losing his interest in the development of the printer’s art, BF is listed in the front of the book as having subscribed to six copies. These cost him one guinea each. On June 5, 1758, he paid his stationer £6 2s. 1d. for having six copies bound in vellum and one in calf. “Account of Expences,” pp. 13, 33; PMHB, LV (1931), 109, 112. The copy sent to Harvard is still there. See also below, pp. 79, 80.

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