Abbildungen der Seite

arising from Experiments and Observations made

at Philadelphia, 1749. — Golden Fish. — Extrac-

tion of Effluvial Virtues by Electricity impracticable 227 Additional Experiments; proving that the Leyden Bot-

tle has no more Electrical Fire in it when charged,

than before; nor less when discharged; that, in

discharging, the Fire does not issue from the Wire

and the Coating at the same Time, as some have

thought, but that the Coating always receives what

is discharged by the Wire, or an equal Quantity;

the outer surface being always in a Negative State

of Electricity, when the inner Surface is in a Posi-

tive State 253

To James Bowdoin, At Boston. 25 October, 1750.

Enclosing Papers on Electricity .... 255

To A Friend In Boston. 25 December, 1750.

Account of an Accident while making an Electrical

Experiment 255

To James Bowdoin. 5 September, 1751.

Introducing Mr. Kinnersley as a Lecturer on Elec-

tricity 257

To Cadwallader Golden. 1751.

Unlimited Nature of the Electric Force . . .258

Queries and Answers referred to in the foregoing Letter.

— The Terms " Electric per se " and " Non-elec-

tric" improper. — New Relation between Metals

and Water. — Effects of Air in Electrical Experi-

ments.— Experiment for discovering more of the

Qualities of the Electric Fluid 259

James Bowdoin To B. Franklin. 21 Dec. 1751.

On the Causes of the crooked Direction of Light-

ning. — Objections to the Hypothesis that the Sea

is the Source of Lightning. —On the Swiftness of

the Electrical Fire 263

To James Bowdoin. 24 January, 1752.

Observations on the Subjects of the preceding Let-

ter.— Reasons for supposing the Sea to be the

grand Source of Lightning. — Reasons for doubting

this Hypothesis. — Improvement in a Globe for

raising the Electric Fire 269

E. Kinnersley To B. Franklin. 3 February, 1752.

New Experiments. —Paradoxes inferred from them.

— Difference in the Electricity of a Globe of Glass

charged, and a Globe of Sulphur. — Difficulty of

ascertaining which is positive and which negative 273

To E. Kinnersley. 2 March, 1752.

Probable Cause of the different Attractions and

Repulsions of the two Electrified Globes mentioned

in the preceding Letter 275

James Bowdoin To B. Franklin. 2 March, 1752.

Effect of Lightning on Captain Waddel's Compass,

and on the Dutch Church at New York . . . 276

James Bowdoin To B. Franklin. 16 March, 1752.

Remarks on Dr. Colden's Letter respecting the

Electricity of the Clouds 279

To E. Kinnersley. 16 March, 1752.

Reasons for supposing that the Glass Globe charges

positively, and the Sulphur negatively. — Hint re-

specting a Leather Globe for Experiments when

travelling 280

To Cadwallader Golden. 23 April, 1752.

Mistake, that only Metals and Water were Con-

ductors, rectified. — Supposition of a Region of

Electric Fire above our Atmosphere. — Theorem

concerning Light. — Poke-weed a Cure for Cancers 283

M. Dalibard's Account of an Electrical Experiment at

Marly 288

Abbe Mazeas To Stephen Hales. 20 May, 1752.

Giving a further Account of the Electrical Experi-

ment at Marly 293

To Peter Collinson. 19 October, 1752.

Electrical Kite 295

W. Watson To The Royal Society. 21 Dec. 1752.

Concerning the Electrical Experiments in England

upon Thunder-clouds 296

To James Bowdoin. 12 April, 1753.

On the Mode of coating Electrical Jars . . . 299
To Peter Collinson. September, 1753.

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

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