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"AN ATTEMPT TO EXPLAIN SOME OF THE PRINCIPAL PHENOMENA OF ELECTRICITY,
BY MEANS OF AN ELASTIC FLUID." From the Philosophical Transactions
Charges of similar bodies as the n-1 power of their corresponding diame-
ters, and independent of the material of which they are made
Equilibrium of electricity in bodies communicating by a canal is in-
Whether the conditions of equilibrium are the same for two bodies com.
municating by a conducting wire as if they communicated by a canal
Containing a comparison of the foregoing theory with Experiment.
§ 3. On the cases in which bodies receive electricity from, or part with it
§ 5. Canton's and Franklin's experiments.
(Mém. Berl. 1756, p. 119)
§ 8. Electric spark.
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 xii (Fig. 2). Repulsion of a particle on a column
Lemma xi. Repulsion of two columns
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
Lemma xv (Fig. 5). Repulsion on a short column close to an electrified
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
Prop. XXXIV (Fig. 8). Theory of a coated plate
Cor. 1. Flat coated plate of any form
Cor. 3. Plate not flat but of uniform thickness
Cor. 4. Density increasing towards the circumference
Cor. 6. Comparison with globe
Prop. 1. Charge of a condenser little affected by the presence of an over-
Part 1. A stricter demonstration, applicable to case of penetration
Cor. 4. Effect of an overcharged body
Cor. 6 (Fig. 11). Two coated plates in communication little affected by
Cor. 7. Canals may be curved as well as straight
sum at their centre of mass
Effect of floor and walls of the room
From MS. No. 18. (Probably an early draft of the theory.)
distance from electrified bodies
Proof of this, and objections to the hypothesis of electric atmospheres
On the hypothesis of electric atmospheres .
Condition of electric equilibrium between conductors in electric com-
Illustration from the equilibrium of air
Definitions of positive and negative electrification, and of over and under
Cor. 1, 2. Effect of two overcharged bodies approaching each other
Cor. 3, 4. Equally electrified bodies repel
Cor. 5. Electrification by induction
Fifth hypothesis, on the communication of electricity between conductor
Attraction and repulsion of electrified bodies
ACCOUNT OF THE EXPERIMENTS.
(1) INVESTIGATION OF THE LAW OF FORCE.
From the MS. No. 7 (apparently prepared for publication).
The electricity of glass is here taken to be positive
First experiment. A globe within a hollow globe and in communication
with it does not become over or undercharged when the whole is
General description of the apparatus
General plan of the experiment
Mechanism for performing the required operations
Second method of trying the experiment
Advantages of the second method .
Estimation of the degree of accuracy of the result
The charge of the inner globe is less than to of that of the outer globe
Hence the electric force is inversely as the square of the distance
Demonstration of this by Lemma 4 (Fig. 13)
Limits between which the law of force must lie, n=2+76
Second experiment—A piece of wood within a vessel formed of two
(2) EXPERIMENTS ON THE COMPARISON OF CHARGES.
Definition of the ratio of the charges of two bodies, illustrated by the
comparison of a disk with a sphere
Method of operation. (Fig. 14)
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
Why the electrification is tested by the gauge electrometer
The bodies to be tested were chosen of nearly equal capacity
The insulating supports of waxed glass. (Fig. 16)
Effects of the electrification of the air
The electrometer threads salted
Estimate of the accuracy of the experiments
Third experiment. On the effect of variations in the arrangement of the
apparatus in testing capacities. (Fig. 17)
Results of the six arrangements
Fourth experiment. Capacities of bodies of different substances, but of
Glass coated with various substances
Effect of the thickness of a plate on its capacity
Fifth experiment. Charge of two small circles compared with that of a
The experiment repeated in a different manner
Sixth experiment. Charge of two short wires compared with that of one
Seventh experiment. Comparison of the capacities of several bodies
Comparison of disk with sphere
Comparison of square plate with disk
Comparison of different cylinders
Eighth experiment. Comparison of the charge of the middle plate of
three parallel plates with that of the outer ones. (Fig. 19)