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454] From these experiments it should seem as if el[ectricity] in

Large circle touched at extremity

at middle

-14.63

13.55

were

Two small circles at 36 inches

13.15

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If the two circles were placed at the same distance from each other in the same manner as in coated plates, and were electrified by wires touching their centers perpendicularly, the quantity of electricity should be

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The quantity of] el[ectricity] in the wire 72 inches long and 19 thick seems to be nearly equal to that in the circle of 18.5 inches. Therefore if we suppose quantity of electricity in a cylinder to be proportional to its length divided by the logarithm

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length

linder is to

of

thickness

that in globe 4761 to tab. log. - or as 1096 to N log. whose diame

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and the quantity of electricity therein is to that in a circle of the same diameter as

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455] A trial plate for Leyden vials consisting of two plates with rosin between.

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456] Therefore the quant. el. in these bodies seems as follows:

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Diameter of the globe = 121, therefore quantity of electricity in globe is to Do in circle of same diameter as 1.56 to 1*.

457] Two trial plates were made on a piece of the large bit of ground glass, one 2.37 inches diameter on place where the thickness = 1.80, computed power = 31.2; the other 2.57 inches diameter where thickness 190, computed power = 34.8.

1=

The first is called S the other L.

The plates of ground glass E and F were each coated on one side with a circle 7.95 inches diameter communicating with coating on the other side. These plates were kept from touching by three bits of sealing-wax. When the coatings were kept at distance 39 from each other this is called plate of air 39 thick, &c.

A piece of wire of the same thickness as the other was made to slide thereon.

When the plate of air was tried against trial-plate S with wire drawn out 12 inches it is expressed

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458] The wire not drawn out is about 40 inches, and may therefore contain about 10 cyl.* inc. of electricity, id est, as much electricity as is contained in circle of 10 inches diameter. Quantity of electricity in additional wire is supposed to be equal to its length [divided] by 4.4.

Both the trial plates together, whose computed power 66, is equivalent to 2A+ 2B + 80 inches of wire + 45 of additional wire, id est, to 73·4+20 + 10·1 = 103.5 inches of electricity, therefore 1 inch of computed power in the glass of which trial plates are made should be equivalent to 1.41 inches of electricity.

By the experiment marked ¶ in [457], a difference of computed power in the trial plates = 3.6, which is equivalent to 5.08 inches of electricity, was equivalent to drawing out wire 20 inches, which is supposed = 4.54 inches of air, which is as near an agreement as can be expected.

By a medium of the experiments, the plate of air 39 thick required wire to be drawn out 11 inches less than A and B, the different experiments varying from 9 to 14, therefore the plate of air contains 2.6 inches more electricity than A and B, id est, it contains 39.3 inches of electricity. The plate of air 343 seemed by 1 experiment to contain 42.7 of electricity.

Therefore plate of air 39 contains 4.94 times more electricity than a circle of same diameter, therefore quantity of electricity therein is to that in circle of same diameter as radius to thickness × 2.06 or quantity of electricity = computed power × 243.

X

459] Four irregular pieces of glass, N, O, P, Q, were coated with circles. The thickness, specific gravity of glass and diameter of circles are marked in [Art. 370], the thickness of glass being found by taking thickness with calipers at center of proposed circle, and finding a part of outside of same thickness and measuring that part by Bird's instrumentt; the computed power of all being just 40. The experiments were tried with sliding wire as former[ly].

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The afternoon when these were tried, hygrometer corks closed in about 20 seconds.

The trial plates being inlarged, tried with large trial plate.

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These experiments were tried in the morning. In the afternoon hygrometer corks closed in about 30 seconds.

460] The plate B was coated with a circle 2.79 inches diameter, computed power 40, and the plate D was coated with a circle 2.73, computed power = 46.

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A piece of the white glass was also coated with a circle 2.85 in. diameter where the thickness was 182, computed power 44.6.

They were tried with the same trial plates.

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White 18 nearly same as B.

+ 24 sep. supposed nearly same as 1st time.

+27 sep. very little.

+ 30 nearly same or rather more than W at 24 with large plate. + 14 sep. a little neg.

N

N

W

+10

do.

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461] The plate A was coated with a circle 2.16 inches diameter, computed power = 22.6; a plate of rosin also, the first which was pressed out after hardening, was coated with a circle 2.51, thickness 102, computed power 2-51*; they were tried with the trial plates described in p. 16 [Art. 457].

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462] Hence it appears that A contains as much electricity as the two double plates. The rosin plate required the wire to be drawn out 18 inches less than them, therefore rosin plate contains 40.7 inches of electricity, and therefore quantity of electricity therein comp. power × †. A contains 36.7 inches of electricity, and therefore as A and B are of the same kind of glass, the quantity of electricity in them computed power × 1.6221056, and B contains 64.96 inches of electricity.

=

The whitish glass plate required the wire to be drawn out 27 inches less than B, D requires 33 less and N requires 14 less, P requires 3 more than N, O 21 less, and Q 37 less than N, therefore W contains 71.2 of electricity, D 72.5, N 68.2, P 67.5, O 73 and Q 76·7.

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+ [So in MS. See note to Art. 464.]

* [Should be 61.7.] [The "real charges" here given are in "circular inches," and the computed power is 8 times the true value, so that the numbers here given must be multiplied by 8/1.57=5.1 to compare them with those given in Art. 370. The diameters of the coatings in these experiments are not the same as those in Art. 370 which are taken from Arts. 508-515 and 672.]

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