Intelligence and Miscellaneous Articles. 447 



Dr. Anderson also offered some remarks on the Glyptopomus minor 

 (Agass.), the specimen of which was obtained from this locality ; 

 and he drew attention to two apparently as yet undescribed fishes 

 also from Dura Den. 



LXXV. Intelligence and Miscellaneous Articles. 



NOTE ON THE STRATIFICATION OF THE ELECTRIC LIGHT. 

 BY MM. QUET AND SEGUIN. 

 A S all electric light arises from an effect of tension, we must 

 -^^ regard it as certain that the brilliant and obscure bands of 

 striated discharges correspond with different tensions diffused alter- 

 nately along the gaseous column. The question is, to know what 

 is the cause of these alternate variations of tension. 



The hypothesis of interferences, probably tried by many physicists, 

 has acquired new importance from the recent experiments of Grove. 

 But in those cases in which the discharges arrive in vacuo by sparks, 

 nothing shows that the discharges corresponding to each pair of 

 sparks are superposed ; and it has not been demonstrated that, by sup- 

 pressing one of the sparks without modifying the conditions of the 

 other, the stratifications are suppressed. On the other hand, amongst 

 the experiments of Gaugain, Pliicker, and Gassiot, and those of our 

 preceding note, there are some in which multiple discharges take 

 place without interfering, and produce effects in which it is always 

 possible to discern the part of each current. 



If we assume that the contact breaker occasions a series of in. 

 terruptions and as many induced currents, we may ask how suc- 

 cessive and irregular impulses should give rise to visible interferences 

 and to bands widely separated from each other and very fixed in 

 their position, such as are obtained in a cylindrical Geissler's tube, 

 by employing a weak battery and applying the baud upon the tube. 

 Must we also assume that there is a series of impulses producing 

 interferences when an ordinary Leyden jaris discharged through the 

 tube, or when, after having converted the tube into a condenser, we 

 discharge the interior upon the armature, and all without the inter- 

 position of any of those ordinary conductors, such as the moistened 

 thread employed by Gassiot, which slacken the discharge and may 

 render it intermittent ? 



Most physicists appear inclined to attribute the principal part to 

 the resistance of the medium. That the nature of the medium has 

 an influence upon the stratifications, is a circumstance indicated since 

 the original discovery. But it still remains to be ascertained how 

 this resistance causes the alternations of the electric tension. By 

 varying the experiments of lliess upon the elcctroscoj)ic states of 

 Geissler's tubes, we have only ascertained that these states change 

 with the resistance placed in the course of the induced currents, 

 and that the same effects of tension are obtained by substituting for 

 the vacuum-tube a column of water*. Until we have some perfectly 



* It ia well kuowa that the resistances modify the aspect of the lumiuoua 



