390 On Stratified Discharges. [June 16, 



The phenomenon of multiple images of the negative terminal as 

 explained above has an important bearing on the nature of electrical 

 discharges in vacuum tubes. For, if the phosphorising radiation con- 

 sists of a recurring series of discrete discharges, the radiation in each 

 series, and a fortiori the radiation as a whole, is discontinuous ; and 

 consequently the electrical discharge, to which it is due, must itself be 

 discontinuous or " disruptive." We appear, therefore, in these 

 phenomena to have an experimental proof, independent of and in 

 addition to those adduced by Mr. De La Rue and others, of a funda- 

 mental point in the theory of these discharges, namely, their disrup- 

 tive character. 



The conclusion, that each main discharge consists of a series of 

 minor discharges, has an interest as throwing light on a difficulty that 

 may perhaps have been felt in respect of one of the conclusions in 

 our second memoir. It was there shown that when the exhaustion 

 was carried to a great degree of perfection, the negative part of the 

 discharge showed signs of a " durational character;" and the difficulty 

 consists in associating the character of duration with that of disrup- 

 tiveness, as attributed to one and the same discharge. But if the 

 explanation of the multiple images here suggested be correct, it may 

 be possible to reconcile the two ideas by considering that the duration 

 is to be understood not as implying a continuous process, but as 

 measuring the interval from the commencement of each main dis- 

 charge until the last of the series of minor discharges belonging to it. 



This idea of rapidly recurring elemental discharges going to form 

 a single discharge is very similar to the state of things which one of 

 the authors of the present paper showed to take place in the case of 

 a discharge from a coil. (See " Proc. Roy. Soc," vol. 25, p. 73.) 

 The revolving mirror showed that each discharge from the coil, 

 though apparently single, and, if not instantaneous, at least continu- 

 ous during the time it lasted, was, in fact, made up of a regular series 

 of elemental discharges, each group of such discharges (constituting 

 a single coil discharge) being composed of like elements. The 

 phenomena above described go to show that even the so-called con- 

 tinuous discharge is made up of very rapidly recurring discharges, 

 each of which is in its turn composed of a group of elemental dis- 

 charges, the successive members of which bear definite relations to 

 each other. 



