﻿Electricity on Streams of Water Drops. 151 



by known voltages, which w T ere gradually increased so as 

 to have at will either the phenomenon of coalescence or 

 scattering referred to by Rayleigh ; (2) to photograph the 

 streams instantaneously so as to obtain the relation between 

 the sizes of the drops in the charged and uncharged streams; 

 (3) to find the reason for the coalescence of the charged 

 drops for small electrifications. 



Apparatus. 



For the remaining photographs the streams were shot 

 under constant pressure in directions nearly vertical from a 

 nozzle of glass, the circular opening of which was *018 cm. 

 Under the pressure used the fine stream rose to a height of 

 about 15 cm. It was found that the scattering at high 

 voltages took place in larger streams, such as used in figs. 1 

 and 2, only at the potential of some thousands of volts 

 obtainable from an ordinary electrical machine. However, 

 with the smaller stream the whole range of phenomena was 

 available by using some 700 or 800 volts from a series of 

 small storage-cells. The glass nozzle was supported in the 

 axis of a short vertical cylinder of brass, 5 cm. in diameter 

 and 3*2 cm. long ; the stream broke into drops about the 

 centre of the upper end of the cylinder. By charging the 

 brass ring to any voltage a charge is induced on the drops 

 as they break from the main earth-connected stream of 

 water issuing from the nozzle. Other things being equal, 

 the charge induced on the drops depends merely on the 

 potential of the inductor, so that even with a piece of ebonite 

 or glass rubbed very slightly the potential of these inductors, 

 and consequently the charge induced on the drops, may be 

 very large. 



A focal-plane shutter was used for instantaneous exposure 

 rather than the spark from an induction-coil and leyden-jars, 

 in order to have the stream absolutely free from all electrical 

 influence except that of the charging ring. In addition to 

 the necessity for very carefully screening off all electrical 

 discharges, the electrical illumination does not offer the 

 same ease of manipulation. For observation with the eye 

 the shadow of the stream cast by an arc lantern was focnssed 

 by means of a good camera lens on a sheet, and the drops 

 viewed by means of a stroboscopic disk. In this way many 

 observations could be made with the eye and instantaneous 

 photographs taken of typical cases. 



