102 Mr. Shelford Bidwell [May 5, 



the steam jet phenomenon was discussed anew in a paper communicated 

 to the Koyal Society by Mr. Aitken. Mr. Aitken said that he did 

 not agree with my conjecture as to the nature of the effect. This 

 led me to investigate the matter again, and to make some further 

 experiments, the results of which have convinced me that I was 

 clearly in error. At the same time it seems to me that the ex- 

 planation which Mr. Aitken puts forward is little less controvertible 

 than my own. Mr. Aitken's explanation of the phenomenon is, like 

 mine, based upon Lord Eayleigh's work in connection with water- 

 jets, but, unlike mine, it depends upon the experiment which shows 

 that water particles when strongly electrified are scattered even more 

 widely than when unelectrified. He believes, in short, that elec- 

 trification produces the effect, not by promoting coalescence of small 

 water particles, but by preventing such coalescence as would 

 naturally occur in the absence of electrical influence. In the elec 

 trified jet, he says, the particles are smaller but at the same time 

 more numerous ; thus its apparent density is increased. 



The chief flaw in my hypothesis lies in the fact that the mere 

 presence of an electrified body like a rubbed stick of sealing wax, 

 which is quite sufficient to cause coalescence of the drops in the 

 water jet, has no action whatever upon the condensation of the steam 

 jet. There must be an actual discharge of electricity. But it is by 

 no means essential, as Mr. Aitken assumes, that this discharge should 

 be of such a nature as to electrify, positively or negatively, the 

 particles of water in the jet. If, instead of using a single electrode, 

 we employ two, one positive and the other negative, and let them 

 spark into each other across the jet, dense condensation at once 

 occurs. [Experiment.] So it does if the two discharging points are 

 removed quite outside the jet. [Experiment.] A small induction coil 

 giving sparks an eighth of an inch in length causes dense con- 

 densation when the electrodes are more than an inch distant from 

 the nozzle and on the same level. [Experiment.] In one experiment 

 a brass tube two feet long was fixed in an inclined position with its 

 upper end near the steam jet, and its lower end above the electrodes 

 of the induction coil. In about three seconds after the spark was 

 started dense condensation ensued, and it ceased about three seconds 

 after the sparking was stopped. No test was needed, though in 

 point of fact one w r as made, to show that the steam was not electrified 

 to a potential of a single volt by this operation. And the time 

 required for the influence to take effect showed that whatever this 

 influence might be it was not induction. 



The inference clearly is that in some way or other the action is 

 brought about by the air in which an electrical discharge has taken 

 place, and not directly by the electricity itself. The idea has no 

 doubt already occurred to many of you that it is a dust effect. 

 Minute particles of matter may be torn off the electrodes by the 

 discbarge, and form nuclei upon which the steam may condense. 

 The experiments of Liveing and Dewar have indeed shown that small 



