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Testing 244, 296, 358, 359
English plate glass 301, 496
Equivalent thickness of compound plates
379

Error, greater with coated plates than
with simple conductors 299; probable
of estimation of capacity 250, 261;
in Exp. I. 234; due to unequal charg-
ing 250

Excess of redundant fluid in coated

plates 560 and note 30

Experiment I. 218, 233, 291, 512, 562
and note 19

II. 235, 292, 561
III. 265, 467

IV. 269, 293, 471, 480, 481
and note 20

V. 273, 447, 448, 452, 454,
472, 473, 474, 475, 681
and note 21

VI. 279, 453, 476, 477, 683
VII. 281, 448, 478, 682 and
note 13

VIII. 288, 542 and note 23

Fair straw 564

f. alk 627, 694

Flannel 514

Floor, effect of 335

Florence flask 521; battery 521

Fluid, electric 195, 216, note 1; real 91;
incompressible 69, 94, 236, 273, 276,
278, 294, 348 and note 3

Force near an electrified surface 154;
inversely as square of distance 232,
512, 513, 562 and note 17

Fore and back room 469
Frame placed below circles 274
Frames 221

Franklin, Benjamin, F.R.S. (1706-
1790) 350 note, 363

Fringe of dirt on coated plates 308, 326,
538

G.

Garden, copper wire stretched round
643

Gauge electrometer 224, 248

General conclusion 291
Gilt straws 249, 394, 567

Glass, different electric qualities of 301,

322

Glass house 378

Glauber's salt 626, 694

Globe, charge of compared with that of
circle 237, 282, 445, 455, 456, 654,
681, 687, note 35

Globe, electrified 20-27, 280; capacity
of 281, 282; compared with double
plate 333, 334

Globe, meaning the world 214

Globe of electrical machine 248, 495,
563, 568, 569

Globe within hemispheres 218, 512, 562,
note 19

Globes, coated 523, 542, 559, 563
Gradual spreading of electricity 302
Guide for the eye 249, 525, 571
Gum lac 371, 374, 376
Gymnotus 437, 601

H.

Hamilton, Dr, Prof. of Philosophy,
Dublin (Priestley, p. 429) 126

Heat, effect on charge of glass, &c. 366,
368, 548, 549, 556, 680, note 26
Heat produced by current 212
Height and size of room 335
Hemispheres 219

Henly (William, F.R.S., d. 1779); linen
draper in London; his electrometer
559, 568, 569, 580

Hissing noise before spark 213

Hot glass a conductor 369, note 26;
compared with cold 366, 368
Hunter (John, F.R.S., b. 1728, d. 1793)
436, 601, 614

Hygrometer corks 459; Smeaton's 468;
common 468
Hypothesis 3, 202

I.

Immoveable fluid 12, 351

Inches of electricity 458, 648, 654
Incompressible fluid 40, 236, 273, 276,
278, 294, 348 and note 3

Increase of charge of globe due to in-

duction 339, 652 and note 24

Induction 44-47, 175-194, 277, 287,
202 sq., 275, 277, 288, 334, 335; cal-
culation of 338

Instantaneous spreading of electricity
307, 319-323, 326
Insulation 100

Iron, conductivity of 398, 576, 687, note
32

J.

Jar 223; capacity of jars 573, 581

K.

Kinnersley (Ebenezer, Physician in Phil-
adelphia, b. 1712) 126, 136, 213; see
new experiments of electricity, Phil.
Trans. 1763, 1773

Knob for discharging 511, 572

L.

Lac 371, 374, 376, 518, 520

Lac solution 494

Measurements of apparatus 219, 255,

273, 275, 466, 472

Mechanism for Exp. I. 222
Mercury 366

Metals, conducting power 397, 398
Method of trying charges 241, note 17
Method of the work 2

Michell (Rev. John, F.R.S., d. 1793) 354
Mineral water warehouse 415

Moist wood 392

Moment, statical 388

Moveable electricity in glass 350
Moveable fluid 12, 350

N.

Nairne, Edward, F.R.S., d. 1806; Mr N.
601; plates from 482 (315); jar 568;
electric machine 559, 568; his own
large one 580; his manner of lacquer-
ing 496; his batteries 585, 616
Needle discharger 572

Lane, Timothy, F. R.S. (b. 1734, d. 1804) Negative electrification 463

136, 213, 601

Lane's electrometer 263, 329, 540, 544,

559, 569, 570, 571, 580

Law of electric force from Exp. I. 291,

note 19

Leakage, electric 260, 264, 393-
Leather 608

Leyden vial 128, 206, 313, 363, 389
Light, Newton's fits 354-

Light round the edge of coating 307,

326, 532; brightest at first charging,
310

Limetree wood 588, 611

Linen thread 244

Lines of discharge of torpedo 400
Link 602

Loops of chain 433, 605

M.

Machine for trying coated plates 295,
337, 340, 366, 495; new for measuring
thickness 517

Machine, electric 242

Magazine of electricity 207, 521, 563
Mahogany 590

Matter 4

Maximum density of electric fluid 20
and note 1

Newton 18, 19, 97

Newton's fits 354

N. O. P. Q. 459, 462, 592

Nuremberg glass 301, 376, 497

Oblong, charge of 284, 479; coatings
320

Oil of vitriol 626, 694
Overcharge 6

P.

pratio of charge spread uniformly on
disk to that collected in circumference
140; estimated value by experiment
276, 281, 289

p ratio of circumference of circle to
diameter 594

Penetration of electric fluid into glass
132, 169-174, 332, 339, 349, 355, 363
Pensylvania, Phil. Soc. of 437
Pith ball electrometer 220, 240, 244,
358, 359

Plate air 134, 340; concave 155; circu-
lar 55-65, 140; thin 73

Plates, coated, lists of 315, 324, 325,
370; theory of 129; two circular 74,
82, 141-144

[blocks in formation]

Repulsion 106; of balls as square of

redundant fluid 386, 525, 563
Repulsion, effect of too great 49
Resistance, electric, varies as length of
conductor 131; what power of ve
locity 574, 575, 629, 686; effect of
heat on 619, 620, 690

Richard 511, 565
Ronayne, Thomas 601

Rosin 336, 371, 461, 464, 488

Rosin varnish 497; experimental 514,

520, 548; plates 518, 555, 560, 594
Roughness dissipates electricity 387
Rows of battery 581

Rules for trial plates 592; for strength

[blocks in formation]

Spark, electric 135-139, 212; none from

torpedo 401; length does not depend
on number of jars 402, 604, note 10
Specific gravity of salt water 587, 588
Specific inductive capacity 332, 339,
notes 15, 27

Spherical shell 18, 19
Spirit of salt, 627, 694
Spirit of wine 524, 631

Spreading of electricity 299-367, 484,
485, 512; gradual 494-500
Springing wire 296

Square, charge of 282, 283, 479 and note

22; plates of various substances 269
Steam, cause of explosion by lightning
137

Stool, electric 420, 612

Strata, conducting, in glass 351, 354
Strength of electrification 355; effect on

capacity 356, 451, 463, 539

System of coated plates 316

[blocks in formation]

Specific gravity 595

Solutions of salt, &c. 689, 694, 695,
696

Trial plates 465

Tubes 575, 632, 633, 636
Thermometer tube 383, 562
Thickness of plates, effect on charge
269, 272; of coated plates 314; of air
plates 341; measurement 517, 594,
595

Three parallel plates 288
Tinfoil 222; discharger 426

Torpedo, 1st wooden 409, 415, 596; 2nd
leather 416, 600, 608, 611, 612, 615;
in basket 421; in sand 422; in net
424. See note 29

Touching, to compare charges 413, 441,
582, 583

Trial plate, theory of 153 and note 17;
list of 590; description of 238, 239,
296, 297, 298, 454, 457, 465, 592;
charge as square root of surface 247,
251, 281; sliding wire 447; sliding
cylinder 547, 567

Trough, torpedo 410, 587

Tubes, measures of 632-635

Undercharge 6

U.

W.

Wainscot 561, 590, 609

Walsh (John, F.R. S., M. P., d. 1795) 395,

396, 401, 415, 421, 424, 430
Wasting of electricity 393, 394, 486, 487
Water, resistance of 398; distilled 617,

621, 688; rain 617; purged of air
624, 692; impregnated with fixed air
625, 693; pump 684; sea 524, 684
Wax 387

Waxed glass 255, 271, 295, 447, 450, 476,
541, 563

Weather, effect of on coated plates 304
Weight of electric fluid 5
White glass 301, 460

Wilcke (Johann Karl, b. 1732, d. 1796)

134

Williamson, Hugh, M.D. 437

Wilson (Benjamin, F.R.S., b. 1721, d.
1788) 125

Wind, electric 125

Wire 219, 240; charge of 279, 479, 683;
trials of 447, 448; connecting, allow-
ance for 337; in straw electrometer
387, 388

Wires compared with canals of incom-
pressible fluid 94, 278 and note 3
"Work," MS. so called 349

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