Page images
PDF
EPUB
[graphic]

Fig. 10.

Neg

[graphic][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][merged small]

experiment, that an artificial electrical accumulation, on a coated surface, may be supposed to proceed, by equal increments.

There are however, a few previous experiments, requisite to be detailed, because they seem to constitute the basis on which the above conclusion rests. *

[ocr errors]

Exp. 1. (fig. 10) A jar, (A) containing five square feet of coated surface, being insulated; its inner coating was connected with the positive conductor, and its outer coating with the negative conductor. The discharging electrometer, fig. 7, was attached to the jar, and the distance between the balls, set to an interval of three-tenths of an inch. In order to estimate the effects of the explosion, the negative ball was connected with the outer coating, through the electrometer, before described; (fig. 8) which last, was also carefully insulated. When three turns and three quarters of the plate were completed, the explosion took place, between the balls, and passing through the wire, elevated the fluid, nine degrees of the scale.

Exp. 2. The outer coating of the jar, being connected with the ground instead of with the negative conductor, the same result was obtained; the fluid was again elevated nine degrees, and with the same number of turns of the plate.

Exp. 3. The outer coating of the jar, (A) being joined

* It may not be improper to state, that in the course of these inquiries, it has been thought desirable to submit to a rigorous examination, some few phanomena, in the science of electricity, already known, but which, nevertheless, do not appear to have undergone a very severe scrutiny, by experiment; not only because this constituted a necessary step in the investigation, but because it seemed more satisfactory to apply the same method of demonstration to facts which have been admitted, as was resorted to for the purpose of further research.

to the inner coating of a second and perfectly similar jar,* (B) and the connection with the negative conductor, or with the ground, completed through the outer coating of this last, the machine was again put in action.-The explosion again passed at the end of the same number of turns, and again elevated the fluid nine degrees. This arrangement is represented in fig. 11; except, that the electrometers must be supposed to remain with the insulated jar, as seen in fig. 10.

Exp. 4. (fig. 11) The matter which had accumulated in the second jar, (B) from the outer coating of the first jár, (^) being discharged; the electrometers, were transferred to this last, in order to ascertain if the accumulation in (B) was precisely similar to that which took place in the first jár (4). The machine being put in action, the explosion again passed at the end of the same number of turns, and again elevated the fluid, nine degrees as before.

Exp. 5. (fig. 12) The electrometers, being again transferred to the jar, (^) as in exp. 1. fig. 10; the second jar, (B) was also insulated, and its inner coating connected with the negative conductor; the outer coatings of the two jars being joined by a metallic rod (m). Under these circumstances, the explosion again occured, at the end of the same number of turns, and with the same effect as before.

Exp. 6. Lastly, the electrometers being transferred to the jar, (B) charged from the negative conductor; the machine was again put in action: the discharge again passed as in the preceding cases, and again raised the fluid nine degrees of the scale. I repeated these experiments with jars,"

* By a perfectly similar jar, is to be understood, a jar which will explode over a given interval with the same number of revolutions of the plate, and cause the fluid to ascend along the scale of the electrometer, fig. 8, the same number of degrees.

not precisely similar; by alternating them, and taking the mean results, and arrived at the same conclusions.

11. We may therefore infer: 1-that precisely the same charge accumulates on a coated surface; whether we suppose the opposite coating to be insulated and connected with one of the conductors of the machine, or whether it be in a freely uninsulated state, or otherwise, whether it operate through an intervening jar. 2-that the charge conveyed to an intervening and similar jar, is precisely equal to the charge conveyed to the first jar, in connexion with the conductor of the machine.

12. These experiments being premised, we pass on to the more immediate object of this part of the inquiry. (10)

Exp. 7. The jars and electrometers being arranged, as in fig. 11; the explosion again passed at somewhat less than four turns of the plate, and again raised the fluid nine degrees, as in exp. 4. The small residuum in the jar, (B) being discharged, the machine was again put in action;—the first jar, (A) connected with the conductor, remaining charged with the previous accumulation; when the same number of turns had been completed, the jar (B) discharged again, and with precisely the same effect on the wire as before.

Exp. 8. (fig. 13) A small jar, (b) containing about a square foot, and two-tenths, of coated surface, being substituted for the jar (B), the explosion took place, at about each turn of the plate, until the jar (A) became fully charged. Now in these instances, the jars, (B,) (b) being charged from the outer coating of the insulated jar, (^) their explo sions became a fair measure of the relative quantities of matter, communicated by the machine. (Exp. 3 and 4) and as these explosions correspond in each case to equal numbers of revolutions, whilst the receiving jar, (A) was charging in any degree short of saturation, it follows, that the accu

mulation in (A,) must have proceeded by equal increments s; and consequently, that equal quantities of matter were thrown on at each turn.

Exp. 9. In order to ascertain if these explosions would take place in a similar way, when two or more jars, were substituted for the jar (A.) The experiment was arranged, as represented in fig. 16; the jars and electrometers being carefully insulated the result however remained the same; the small jar discharged as before, and in precisely the same way. The explosions of a second jar, therefore, in connexion with the opposite coating of a charging surface, whether in a divided or undivided state, may be also considered as a fair measure of the relative quantities of matter accumulated.

Exp. 10. (fig. 12). Two equal and similar jars, (^) (B) were insulated, and connected, one with the negative, and the other with the positive conductor, as in exp. 5;-the outer coatings being joined by a metallic rod (m). In this case, as much matter as was conveyed into the positive jar, (^) was evidently taken from the negative jar, (B) and reciprocally. The effects of the accumulation in either system, estimated as before, at given intervals, were precisely the same, and corresponded to an equal number of turns of the plate: consequently, the respective quantities which continued to accumulate in the opposite system after each discharge, must have been also precisely similar.

13. These experiments relate to quantity; and they evidently shew: 1-that equal quantities are given off at each revolution of the plate, (if in a state of uniform action,) whether to an uncharged surface, or to a surface charged in any degree short of saturation. 2-that a coated surface, charging in any degree short of saturation, receives equal quantities, in equal times; all other things remaining the

« PreviousContinue »