The 2nd column is weight required to balance it in that position. The 3rd is the same thing in the 2nd trial. The 4th is the difference of these numbers, or bulk of intermediate portion of glass. The 5th is the same thing in 2nd trial, and The 6th is the mean between them. The 7th is the circumference in the middle of that space. [after this a table for the narrower half of 1st cylinder, and in M. 7 for 2nd, 3rd and 4th cylinders. M. 8 and M. 9 is a table of 11 columns. 1st column, distance from mark. 2nd Mean loss [of weight] for 2 inches. 3rd Supp[osed] mean circumference. 4th Log. loss. 5th Log. supp. circ[umference]. 6th Log. thickness] × p. 7 Thick. × p [p = ratio of circumference to diameter]. M. 10. Measures of the circumference and substance of glass in jars and cylinder. Marks with file are made at the extremities of the whole space, and the numbers begin with the space marked with double mark. # By mean circumference is meant the mean between the inside and outside circumference. The circumference was measured by a slip of tinfoil put round, and the intersection marked with knife. The substance of glass was found by hanging it to end of sliding ruler fastened to one end of balance, and weighing it in water; and by sliding the ruler I made more or less of it to be immersed, and knew the difference of the space immersed. M. 11. Specific gravity of different pieces of white glass. The small jar being broke, a 2nd was measured. Thickness measured by calipers in 4 different rows parallel to axis and in 5 different places in each row, beginning at a scratch with a file near bottom. [Here follow the measures.] The thickness was then tried in 4 different parts of circumference at 4.4 inc. distance from scratch. It was then weighed in water in the same manner as the others. The jar was dried before each trial, and before the 3rd was rubbed with solut. p. ash*, which made the water stick less to side, for which reason it is supposed most exact. The circumference was measured in two parts of the middle space, and they came out both the same. 595] M. 12. Measures of coatings to jars and cylind.† A coating made to 2nd small jar extending to 4.4 inches from scratch. Comp. power 680.7. = Coating to white cylinder extends 9.86 inches from double mark. Comp. power 684·1. A coating made to 4th green cyl. extending 7 inches from mark. Comp. power 318.2. A mark was made on wide part, extending 7·16 inc. from new mark. Comp. power 600-7. M. 13. A mark made on 2nd green cylinder 11 inches from first towards thick end, and the tube cut off about 1 inch from 1st mark. A coating made to the thick part extending 8:55 inches from 2nd mark. Comp. power 600. * [Pearl ash.] = [See Art. 383. The computed power here is 8 times the true value, and there is no correction for spreading of electricity.] 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 x 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 and therefore the time the whole circuit in given time is as a + 1 " 1+x 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 x to [1], the quantity of electricity which passes through your body is as passes through your body is given. 1 1 1 + x' and the rapidity with which it 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 charge8 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 2 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 la which passes through torp. is increased to 2n, quant. el. which passes and therefore it should require about 9 times quant. el., or about 5 times the charge to give the same shock out of water as at present. 1 row jars el. to 11 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. 2 rows briskish in elbows. * [Art. 416.] |