Furthermore, since the observations upon the quantities occurring in equation (4) [see (8) p. 55 of this volume] are all made upon the same drop, all uncertainties as to whether conditions can be exactly duplicated in the formation of successive clouds obviously disappear. There is no theoretical uncertainty whatever left in the method unless it be an uncertainty as to whether or not Stokes’s Law applies to the rate of fall of these drops under gravity. The experimental uncertainties are reduced to the uncertainty in a time determination of from 3 to 5 seconds, when the object being timed is a single moving bright point. This means that when the time interval is say 5 seconds, as it is in some of the observations given below, the error which a practiced observer will make with an accurate stop watch in any particular observation will never exceed 2 parts in 50. The error in the mean of a considerable number of concordant observations will obviously be very much less than this. Since in this form of observation the of equation (5) [(8) of this volume] is zero, and since is negative in sign, equation (5) reduces to the simple form:[40] [Pg 64] It will perhaps be of some interest to introduce two tables from this paper to show the exact nature of these earliest measurements on the charges carried by individual particles. TABLE IIa SERIES 1 (BALANCED POSITIVE WATER DROPS) Distance between plates .545 cm. Measured distance of fall .155 cm. Volts Time 1 space Time 2 spaces 2,285 2.4 sec. 4.8 sec. 2,285 2.4 4.8 2,275 2.4 4.8 2,325 2.4 4.8 2,235 2.6 4.8 2,325 2.2 4.8 2,365 2.4 4.8 2,312 2.4 4.8 TABLE IIb SERIES 2 (BALANCED POSITIVE WATER DROPS) Distance between plates .545 cm. Measured distance of fall .155 cm. Volts Time 1 space Time 2 spaces 2,365 1.8 sec. 4.0 sec. 2,365 1.8 4.0 2,365 2.2 3.8 2,365 1.8 4.0 2,395 2.0 4.0 2,395 2.0 4.0 2,395 2.0 3.8 2,365 1.8 4.0 2,365 1.8 4.0 2,365 1.8 4.0 2,374 1.90 3.96 TABLE III Series Charge Value of Weight Assigned 1 3 4.59 7 2 4 4.56 7 3 2 4.64 6