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FIRST PUBLISHED PAPER ON ELECTRICITY.

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“ AN ATTEMPT TO EXPLAIN SOME OF THE PRINCIPAL PHÆNOMENA OF ELECTRICITY,

BY MEANS OF AN ELASTIC FLUID." From the Philosophical Transactions

for 1771 (p. 1–50).

Part I.

ARTICLES

Hypothesis

1-6

Repulsion of a cone on a particle at the vertex

7-11
Force between two bodies over or under charged

13-15
Equilibrium of the electric fluid

16, 17
Repulsion of a spherical shell

18, 19
Equilibrium of electricity in a globe

20-27
Two plane parallel plates

28-38
Canals of incompressible fluid

39-53

Pressure of electric fluid against a surface.

54

Circular disk

55_-66
Charges of similar bodies as the n-1 power of their corresponding diame-
ters, and independent of the material of which they are made

67–72

Charge of a thin flat plate independent of its thickness

73

Two parallel circular plates

74483

Equilibrium of electricity in bodies communicating by a canal is in.

dependent of the form of the canal

84-93

Whether the conditions of equilibrium are the same for two bodies com-

municating by a conducting wire as if they communicated by a canal

of incompressible fluid.

94_96

Molecular constitution of air

97

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98

99, 100
101-105
106-117

117

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(Mém. Berl. 1756, p. 119)

& 8. Electric spark .

134

135-139
lent thickness

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Prop. XXIX (Fig. 1). If the fluid uniformly spread on a circular plate is

to that collected in the circumference as p to 1 the capacity of the

plate is to that of the globe as p+1 to 2p+1

Prop. xxx. Capacity of two disks at a finite distance

Cor. 1. Capacity in terms of p

Cor. 2. Capacity when the density is supposed uniform

Cor. 3. The place in which the canal meets the disk is indifferent only

when the fluid is in equilibrium

Lemma xi (Fig. 2). Repulsion of a particle on column

Lemma XIII. Repulsion of two columns

Lemma xiv.

Lemma xv (Fig. 3). Action of a uniform cylinder on an external point

Cor. Potential of middle and end .

Prop. xxxi (Fig. 3). Charge of cylinder compared with that of globe

Cor. Upper and lower limits of charge

Prop. XXXII (Fig. 4). Charge of two equal cylinders at a finite distance

Prop. XXXIII. Ratio of charges of B and b may be deduced from the

ratios of B and b to C.

Lemma xv (Fig. 5). Repulsion on a short column close to an electrified

plate

Lemma xvi (Fig. 6). Two equidistant concave plates

Cor. 1. Definition of corresponding points, &c.

Cor. 2. Density increasing towards the circumference

Lemma XVII (Fig. 7). Concave plate compared with flat one

Cor.

Prop. XXXIV (Fig. 8). Theory of a coated plate

Cor. 1. Flat coated plate of any form

Cor. 2. Flat circular plate

Cor. 3. Plate not flat but of uniform thickness

Cor. 4. Density increasing towards the circumference

Cor. 5. General conclusion

Cor. 6. Comparison with globe
Cor. 7. Form of plate indifferent .
Cor. 8. Charge directly as surface and inversely as thickness
Prop. XXXV (Fig. 9). Theory of conducting strata in the glass plate
Prop. XXXVI (Fig. 10). Penetration of glass by fluid
Cor. 1. Equivalent thickness of plate if there were no penetration
Cor. 2. Thickness of coatings indifferent .
Prop. XXXVII. Density more nearly uniform than if there had been no

penetration

Cor. Distribution probably nearly the same as in plate of air of equiva-

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THOUGHTS CONCERNING ELECTRICITY.

ACCOUNT OF THE EXPERIMENTS.

(1) INVESTIGATION OF

THE LAW OF FORCE.

From the MS. No. 7 (apparently prepared for publication).

(2) EXPERIMENTS ON THE COMPARISON OF CHARGES.
From the MS. Nos. 9 and 10 (apparently prepared for publication).

Intention of the experiments

Definition of the ratio of the charges of two bodies, illustrated by the

comparison of a disk with a sphere

Method of the experiment

The Trial-plate. (Fig. 13).

Arrangement of the apparatus

Method of operation. (Fig. 14)

Theory of the experiment

Interpretation of the result

The testing electrometer

237

238

239

240

241

242

243

244

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Method of testing.

Advantages of the method

Capacity of the trial plate

The gauge electrometer

Form of electrometer used in the later experiments. (Fig. 30)

Estimation of error arising from unequal electrification in the two trials

Comparison of the capacities of two bodies

Demonstration

Why the electrification is tested by the gauge electrometer

The bodies to be tested were chosen of nearly equal capacity

Measurements of the apparatus

The insulating supports of waxed glass. (Fig. 16)

Electrification of air

Effects of the electrification of the air

The earth-connexions

The electrometer threads salted

Leakage of the Leyden vials

Estimate of the accuracy of the experiments

Probable cause of error

Weak charges always used .

Reason for this

Third experiment. On the effect of variations in the arrangement of the

apparatus in testing capacities. (Fig. 17)

Six different arrangements

Results of the six arrangements

Conclusion.

Fourth experiment. Capacities of bodies of different substances, but of

the same shape and size

Glass coated with various substances

Method of the experiment

Effect of the thickness of a plate on its capacity

Fifth experiment. Charge of two small circles compared with that of a

large one. (Fig. 18).

Results of the experiment

The experiment repeated in a different manner

Comparison with theory

Remarks on the calculation

Bearing on the theory

Sixth experiment. Charge of two short wires compared with that of one

long one

Comparison with theory

Seventh experiment. Comparison of the capacities of several bodies

Comparison of disk with sphere

Comparison of square plate with disk

Oblong plate

Cylinder

Comparison of different cylinders .

Disturbing cause

Eighth experiment. Comparison of the charge of the middle plate of

three parallel plates with that of the outer ones. (Fig. 19)

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