284 "Journal of Experiments, NOT.}. 1773 



at 90, and to prevent the shock being too strong it had its choice whether it 

 would pass through my body or some salt water, the wires in the salt water 

 being brought within such a distance that the shock was weak when taken 

 by the blunt body. I then found that if I took it with the point I could scarce 

 perceive any spark. 



The experiment was tried in the same manner with a large jar. The shock 

 was very sensibly less though the point was approached almost as fast I could. 



573] Whether shock of one jar is greater or less than that of twice that quantity 

 of fluid spread on four jars*. 



It was found that if the jars 3 and 4 were electrified in a given degree, and 

 their electricity communicated to the jars i and 2, the shock produced by dis- 

 charging them was nearly the same, or of the two rather more, than that pro- 

 duced by discharging the jar i or 2 by itself. The shock of the jar 3 was found 

 to be very sensibly greater than that of jar 4. 



It was tried with the wooden rod, the jars to be electrified being placed in 

 contact wtih the tinfoil thereon, and when they were sufficiently electrified 

 those to which the electricity was to be communicated being approached till 

 they touched the rod, all four standing on the same tin plate. The jars were 

 electrified till the straws separated -9 inch. 



N.B. The jars i and 2 contain pretty nearly the same quantity of electricity 

 and their sum is nearly equal to the sum of jars 3 and 4. The quantity of elec- 

 tricity in jar 3 exceeds that in jar 4 in the ratio of 37 to 27, or of 4 to 3 nearly f. 



574] Comparison of the diminution which the shock receives by passing through 

 water in tubes of different bores, and whether it is as much diminished in passing 

 through 9 small tubes as through the same length of one large tube the area of whose 

 bore is equal to that of the 9 small ones%. 



Nov. 1773. It was tried whether a shock was as much diminished by passing 

 through a glass tube filled with water, 37 inches of which held 250 grains of 

 water, as in passing through 9 tubes, 37 inches of all which together held 258 

 grains of water, the length of water which it passed through being the same in 

 both cases, namely about 40 inches. 



Two jars were used, and charged till the straw electrometer separated to 

 3 + o. The water in the tubes was mixed with a very little salt, and the shock 

 just enough to be perceived. 



I could not be certain that there was any difference, but if any, that with 

 the single tube seemed greatest. The shock was then made to pass through 

 7 of the small tubes, 37 inches of which hold about 200 grains of water. The 

 shock was then sensibly less than with the large tube. 



It was afterwards tried through what length of a tube, 37 inches of which 

 held 44 grains, the shock must pass, so as to be as much diminished as in passing 

 through 44^ of the large one. 



* [Art. 406 and Note 31.] f [ Art - 68 5-] t L See Art - 56.] 



