EXPERIMENTS WITH THE ARTIFICIAL

TORPEDO.

596] Torp. 1 in water touching sides*.

3 rows 1 felt plain shock in hands.

more brisk

in Do.

Without any torped. jar 4 was perceptible.

I could not perceive any sensible difference in the conducting power of the water I used & of sea water, but the difference caused by mixing part of rain water with the sea water was scarcely perceptible.

so that there seems no reason to think that the resistance of water about the saltness of sea water varies in a quicker ratio than that of the quantity of salt in it.

* [Art. 415.]

[3 rows of battery electrified till the electrometer separated to 11.]

[These numbers are those of the jars of the first row of the battery. See

Art. 583.

§ [This should be conducting power, instead of resistance. The numbers then agree with those in Art. 684.]

Without torpedo jar 1 + 2 + 4 was very sensible in elbows, but 1 + 2 was felt only in wrists.

597] Let a given charge be passed by double circuit through your body and another circuit; let the quantity of electricity which passes along the second circuit be to that which passes through your body as to 1; the rapidity with which the fluid passes through your body is the same whatever is the value of x, and the quantity which passes through your body is as 1 + x.

If the resistance which the electricity meets with before it comes to the double circuit is to that which it would meet with in passing through your body alone as a to 1, the force required to drive electricity through the whole circuit in given time is as a + and therefore the time

1

9
1 + x
1 + x
1 + a + ax'

and the velocity with

In trying resistance of liquors by double circuit, if the quantity of electricity which passes through the liquor is to that which passes through your body as a to [1], the quantity of electricity which passes through your body is as

passes through your body is given.

1

1

and the rapidity with which it 1 + x

In trying it with single circuit, if resistance el. in passing through liquor is to that in passing through your body as x to 1, velocity of electricity is as and the quantity is given, therefore in both ways 1+x of trying it, the greater x is, the more exact will be the method, and both methods will be equally exact if x is given or very great, supposing the strength of the shock to be as the quantity of electricity into its velocity †.

(16

598] Shock produced by charge 22 in water bears the proper

44 6

proportion to that caused by charge 8 out of water.

(16

* [Should be inversely as 1+x. The rest is a correct statement of the strength of derived currents according to the law afterwards published by Ohm. See Art. 417.]

+ [The "velocity" is what is now called the strength of the current. The strength of the shock is assumed to be proportional to the energy of the discharge. See Arts. 406, 573, 610, and Note 31.]

It is supposed that it required about 23 the charge to give a proper shock in water as [it does] out, or it is supposed to require 5 times quant. el. It is supposed too that it requires 2ce charge of 3 times quant. el. to give same shock with torp. out of water as without torp.

(body

Let quant. el. which passes through torp. be as 2, if quant. el.

water

which passes through torp. is increased to 2n, quant. el. which passes

and therefore it should require about 9 times quant. el., or about 51 times the charge to give the same shock out of water as at present.

1 row jars el. to 1 by straw el. and commun. to rest, a shock just sensible in elbows.

1 + 2 + 3 + 4 + 5 + 6 + 7: just sensible in hands.

D°+ 1 row: stronger than N° 1.

In water.

2 rows: plain in hands,

1 row: just sensible,

3 rows rather stronger than 2 D° out of water.

600] Tu. Apr. 4 [1775] 2nd leather Torpedo.

Out of water,

5+6 +7: very slight in fingers.

2 rows only in hands, there seemed to be something wrong.
4 rows brisk in elbows.

601] Sat. May 27 [1775] with 2nd leather Torpedo under water, 3 rows charged to 1 on electrom.*

Shock with one hand to one person seemed stronger, to another weaker than with both.

Communication being made with metals instead of the hands, no shock was felt, but when all the rows were charged to 3, Mr Ronayne felt a small shock.

With wooden Torpedo, 1 row to 11; shock passed across 27 links of heavy chain with light. It also passed across 4 links of small chain with light, but not across 6.

Without Torpedo, 5 + 1 + 2 to 1; shock passed with light through electrom., no candle in room; also with torp. charged as in trial.

On a former night in trying wooden Torp., charged I believe much the same as this time, no light was perceived, though Mr Hunter felt a shock, but very weak.

One candle in room, hid as well as possible behind screen.

With Gymnotus, all rows charged to 31.

Doubtful.

Dr Priestley and Mr Lane touching with 1 hand at same time, Dr Priestly felt shock extend to elbow.

A former night, 3 rows charged to 11, Mr N. thought the shock extended to elbow; no one else thought so.

Sat. May 27 [1775].

602] Old Torp. out of water 2B+ A (8·1)†, tried with metals, weak shock.

New torp. B+ A (4·6) as strong as former.

The old Torp. tried with one hand holding metal against bottom side, in other hand holding bright link.

row.

[Art. 419. The (artificial) Gymnotus is not elsewhere mentioned.]

+ [The numbers in brackets are the charge communicated to the battery or the See Art. 583.]

3A (3) no shock, with B (3.6) a very slight shock when torp. was just wetted, none else.

With long link, not bright, 3A, (3), sometimes felt it, not always; with 2A never.

With wire of same size bright without link, seemed not to feel it so well.

With small link not bright no shock with B+ A (4.6), but there was with B + 2A (5-6); with bright wire without link felt shock with B+ A (46), but not with B. (3.6).

With dirty link 2B+ A (8.1), sometimes a small shock, not always; with 2B + 2A (9·1), certain.

603] Tried with Lane's electrom.; dirt unaltered.

604] It was tried whether distance on Lane's electrom. at which jars discharged was the same at the same separation of straw & pith ball electrom. whether number of jars was great or smallt.

This was tried first by laying small knob'd Lane on wire while jars were charging, and afterwards by charging jars, without Lane lying on wire, to a little greater and little less degree by electrom. than what it was before found that they discharged at; then touching them with Lane, I could not perceive that the number of jars made any difference.

It was tried by comparing 1 & 4 jars with straw el. at 2 and by comparing 1 and 7 rows of battery with pith balls at 1.