circle from the perpendicular bar when they were placed at 36 inches distance, were diminished in about the ratio of 2 to 3*.

475] Tu. Dec. 31 [1771]. Th. 51°. S. H. 18.

Small circles at 18 inches distance.

476] Comparison of 2 wires 3 feet long and inch in diameter with 1 of 6 feet long and 185 in diametert.

The wires were placed parallel to each other, horizontal and perpendicular to the horizontal bar. They were touched almost close to one extremity by the same wires and in the same manner as the circles in the former experiment.

The

That end of the wires near the part which was touched was suspended by silk, the other end was supported on waxed glass. distances were the same as in [Art. 472].

477] Fr. Jan. 3 (1772). Th. 50°. S. H. 191. C. H. + 2.

and

By theory [Art. 152], the proportions should be between those of

478] Comparison of different substances tried in the usual manner*. The large tin circle suspended by silk.

[Article].

+ Double plate ground glass A, thickness 3, diam. coating 1.82, comp. power 11.04.

A tin cylinder 35.9 inches long and 2·53 in diameter, on do.

A tin cylinder 54.2 long and 73 in diameter, on do.

Brass wire 72 inches long and 185 in diameter, on do.

479] According to the 5th and 6th article of last page, the quantity of electricity in the square is to that in a circle of the same area as 1.08 to 1, and that in square to that in oblong of the same area as 991 to 1.

By comparing the 2nd article with the 3 last, the quantity of elec(thick cylinder

tricity in thin cylinder may be to that in a globe whose diameter

(wire

Therefore, if we suppose that the real quantity of electricity in any cylinder is to that in the globe whose diameter equals the length of the 2ce length thickness

cylinder as 1 to N. L.

2e length

or as 4964 to tab. log

thickness'

it will agree very well both with theory and experiment.

Or by comparing this with the first article, the quantity of electricity in any cylinder is to that in a circle whose diameter is equal to 2ce length the length of the cylinder as 759 to tab. log thickness

Comparative charges of bodies tried in the former experiment.

By means of this experiment and that of 1771. [Arts. 455, 456.] If the charge of the globe is called 1, that of the circle will be 992, therefore, by comparing 6th and 7th articles with 5th, the charges of the square and oblong will be 957 and 965.

By comparing arts. 1 and 5, the charge of circle on waxed glass is greater than on silk strings in ratio 1.042 to 1, and therefore if charge of cylinders and wire on waxed glass are supposed greater than on strings in the ratio 1.021 to 1,* the charges of thick cylinder, thin cylinder and wire will be 1.028 980 and 966.

Comparison of different substances tried in the usual way+ except that in the first experiment the touching wire rR and the wire RS were of brass 185 thick.

* [The cylinders and wire were supported on waxed glass at one end only.]

[Exp. IV. Art. 269.]

481] Result of this and Art. 471. [Same as Table, Arts. 269, 270.]

TRIALS OF LEYDEN VIALS.

482] The plates from Nairne made out of the same piece of glass were coated with circles of tinfoil as below*.

The plates D, E, F, G of Nairne were compared with the double plates A and B by means of the trial plates A and B and an additional wire sliding on the electrifying wire Mm.

30

of the wire Mm is inches, the additional wire is •15

of the same thickness. The wire Bb is 9 inches long.

6 B 3rd

[See Art. 315. The computed power as given in this part of the Journal is the square of the diameter divided by the thickness, which is eight times the computed power as defined in Art. 311, and calculated in Art. 315.]