Crown with slits contains 27 inc. el. more than wh. cyl.

N.B. This is meant in dry weather & with usual deg. el.

The crown with slits exceeded wh. cyl. by 42.7 more with electrom. at 3+1 than at 1+ 3, and H with oblong exceeded wh. cyl. by 43 more with electrom. at 3+1 than at 1+ 3, but it must be observed that this was only one day's observ.

It is plain that the numbers in the 8th or last col. ought to be equal to those in the 6th, as is nearly the case.

664] Whether charge of coated glass bears the same proportion to that of another body whether el. is strong or weak *.

pos.

P. 61 [Art. 535], E on neg. side tried against sliding tin plates on

Charge of E was part less with straw el. at 3 + 1 than at 1 + 3, the diff. between neg. and pos. el. was much too small to be certain of.

P. 66 [Art. 538], a ball blown at end of therm. tube tried in same Charge just the same whether electrom. at 1 + 3 or 3 + 1.

manner.

P. 68 [Art. 538], charge D° less with el. at 3+1 than at 1 + 3.

50

P. 82 & 84 [Arts. 551 & 55], tried with machine for finding quant. el. in common plates. No perceptible diff. between charge of E whether tried with el. at 1 + 3 or 3 + 1.

665] By P. 9 [Art. 661], it should seem that el. spread. 034 inc. more on surface with greater degree of el. than with smaller, and therefore as the diam. coating of E or D is 2.16.

less with

So that it should seem as if the charge of a coated plate in which the spreading of the el. was prevented would be at least the stronger degree el. than with the weaker.

666] By exper. of P. 69 [Art. 539], it appeared that the charge of tin cyl. was to that of D + E when electrified very weakly as 1.28 to 1, and by P. 70 [Art. 539] as 1·24 to 1. By mean as 1.26 to 1†.

By mean of P. 76 [Art. 545], the charge of the same cyl. was to that

of D + E when electrified in the usual degree as 1:33 to 1.

By mean of P. 77 [Art. 546], it came out as 1.37 to 1, but this last can not be depended on, as wire for making communication with ground was forgot to be fixed.

+ [See Arts. 358, 539, 545.]

* [Arts. 356, 451, 463, 535, 539, 551.] The comp. charge of the cyl. is 484 glob. inc. The real charge, supposing that the wire contains 36 glob, inc. less when joined to cyl. than to D+E=73-6, and therefore its real charge exceeds the computed in the ratio of 152 to 1.

[See

Note 25.]

667] It should seem that the charge of D and E is increased 8 by spreading of el. when elect. in usual degree, therefore if we suppose that the spreading is insensible when electrified in very small degree, the charge of a glass plate is less in proportion to that of another body when electrified with usual degree el. than when elect. with a very small one in ratio of 1.26 to 151, or of 5 to 6.

The same plate air contained 2 inc. el. less when resting intirely on machine than when resting by 1 corner.

[By Art. 517], Pl. air 2 cont. 1 inc. el. less than D + E.

By res. P. 5 [Art. 653], D, E, and F cont. 26.3 glob. inc.

Therefore pl. air 1 contains 27 glob. inc.

669] [Table of plates of air given in Art. 343.]

diam. thickness

above N, the value of N in 3rd col. being 1, in 2nd 1·05, in 3rd 1∙1, and

in 4th 1.15.

The numbers in the 3rd column seem most uniform, and therefore it

seems likely that [if] the

+ [See Art. 347.]

671] If we suppose the el. to spread 07 inc. on surf. thick plates and '09 on surf. thin ones, the result of Nairne's plates is as follows*.

thick white

thin white

Р

672] Computations of other flat plates of glass, &c.

N

[Art. 509] P. 20

[Art. 515] P. 28

=

=D+E+F- 5.8

3.8

75.1

Art. 527] P. 53 small ground crown = D + E + F - 4!)

Art. 528] P. 54

[In Art. 324 the "Real charges" of this table are multiplied by 122 for easy comparison with the computed charges.]

The diam. was corrected on supposition that elect. spreads 07 if the thickness of glass = 21, and 09 if thickness 08, and so in proportion in other thicknesses.

674] [Table given in Art. 371.]

The correction of the diameter is the same as would be used according to the preceding rule to a glass plate of 2° the thickness, only the correction used is never less than

675] On the glass cylinders.

inch.