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CLXXI: TO THOMAS HUBBARD, AT BOSTON - Benjamin Franklin, The Works of Benjamin Franklin, Vol. III Letters and Misc. Writings 1753-1763 [1904]

Edition used:

The Works of Benjamin Franklin, including the Private as well as the Official and Scientific Correspondence, together with the Unmutilated and Correct Version of the Autobiography, compiled and edited by John Bigelow (New York: G.P. Putnam’s Sons, 1904). The Federal Edition in 12 volumes. Vol. III (Letters and Misc. Writings 1753-1763).

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CLXXI

TO THOMAS HUBBARD, AT BOSTON

London, 28 April, 1758.

Sir:—

In pursuance of Mr. Winthrop’s memorandum, which I lately received from you, through the hands of Mr. Mico, I have procured and delivered to him the following things, viz.:

A mahogany case lined with lead, containing thirty-five square glass bottles, in five rows, seven in a row.

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 than 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 difficulty in lining the inside with tinfoil, but that is chiefly got over by cutting it into narrow strips, and guiding them in with a stick flat at one end, to apply the more conveniently to the pasted side of the glass. I would have coated them myself, if the time had not been too short. I send the tinfoil, 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 tinfoil is ten 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, through which the long communicating wires pass, that connect all the bottles in one row.

To form occasional communications with more rows, there must be, on the long wires of the second and fourth rows, four other movable wires, which I call cross-wires, about two inches and a half long, with a small ball of any metal about the size of a pistol-bullet at each end. The ball of one end is to have a hole through the middle, so that it may be slipped on the long wire; and one of these cross-wires is to be placed between the third and fourth bottles of the row at each end; and on each of the above-mentioned 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 row, you turn two of them back on the first, and two on the fifth row, 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 completed with just the number of rows you want.

The brass handles of the case communicate with the outside of the bottles, when you wish to make the electrical circuit.

I see, now I have wrote it, that the greatest part of this letter would have been more properly addressed to Mr. Winthrop himself1 ; but probably you will send it to 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 obliged humble servant,

B. Franklin.

P. S.—I beg the College will do me the favor to accept a Virgil, which I send in the case, thought to be the most curiously printed of any book hitherto done in the world.1

[1 ]At that time Professor of Mathematics and Natural Philosophy in Harvard University, for which institution the electrical apparatus described in this letter was designed.—S.

[1 ]A copy of Baskerville’s quarto edition of Virgil, printed the year before at Birmingham, and perhaps the most beautiful of the various works by which this celebrated type-founder and printer gained the praise of “uniting, in a singularly happy manner, the elegance of Plantin with the clearness of the Elzevirs.”—S.