Hypothesis of the Sea being the grand Source of
Lightning retracted. — Positive, and sometimes
negative, Electricity of the Clouds discovered. —
New Experiments and Conjectures in Support of
this Discovery. — Observations recommended for
ascertaining the Direction of the Electric Fluid. —
Size of Rods for Conductors to Buildings. — Ap-
pearance of a Thunder-cloud described . . . 300
To Peter Collinson. 23 November, 1753.
Notice of another Packet of Letters . . .314
Proposal of an Experiment to measure the Time taken
up by an Electric Spark in moving through any
given Space. By James Alexander, of New York 315
Answer to the Foregoing 317
Remarks on the Abbe Nollet's Letters to Benjamin
Franklin on Electricity. By David Colden, of
New York. 4 December, 1753 . . . .319
Electrical Experiments, with an Attempt to account for
their several Phenomena. Together with some
Observations on Thunder-clouds, in further Confirm-
ation of Mr. Franklin's Observations on the Posi-
tive and Negative Electrical State of the Clouds.
By John Canton. 6 December, 1753 . . . 330
To James Bowdoin. 13 December, 1753.
Concerning the Light emitted by Salt Water.—
The Abbe Nollet's Letters on Electricity . . 337
To Peter Collinson. 18 April, 1754.
Additional Proofs of the Positive and Negative
State of Electricity in the Clouds. — New Method
of ascertaining it 340
Experiments made in Pursuance of those made by Mr.
Canton, dated December 6th, 1753; with Explan-
ations, by Benjamin Franklin. 14 March, 1755 . 341
Turkey killed by Electricity. — Effect of a Shock on
the Operator in making the Experiment . . 346
To John Lining. 18 March, 1755.
Differences in the Qualities of Glass. —Account
Vol. v. h