Oct. 6, i8Si] 



NATURE 



551 



Fig. 7 represents the appearance of (in the mirror) a carbonic- 

 acid tube with the slit attached. This tube, viewed by the eye, 

 .shows flake-like fluttering stria?, with a slight tendency to floccu- 

 lency near the head of the column. The commencement of the 

 discharge is at the right hand, and the negative terminal at the 

 top. I'he drawing fairly represents the appearance of the upper 

 part or head of the column of strias during one complete coil- 

 discharge. When the battery-surface exposed is small, the 



whole consists of, first, three or four columns of strire of de- 

 creasing length, and afterwards of an almost unbroken field of 

 stria;, tach ..f the initial columns is perfectly stratified ; and 

 the s^ame dsposition of strife prevails throughout the entire dis- 

 charge. 'I he stria: which hll the main part of the field present 

 a proper motion, that is a m tion along the tube during their 

 period of existenci-, usually >tcady and towards the positive. In 

 this case it is nearly uniform, but slightly diminishing towards 



the end. These strlje are for the most part unbroken, but are , terminal is at the top. The principal interest of this lube ccn- 

 occasionally interrupted at apparently irregular intervals. When sists in showing the influence of diameter upon the velocity of 

 the battery-surface is increased, the elementary stria; are more proper motion. The wider the tube the freer, it seems, the striae 

 broken, and near the head of the column the interruptions occur are to move. 



as in the figure. The same fact may be observed by comparing lubes difltring 



Fig. 8 represents the discharge in a hydrogen-lube of conical in diameter, but in other respects the same ; but the cot ical tube 

 form, the diameter of which varied from capllary size to half brings out the fact in the most striking manner, 

 an inch, the capillary end being at the bottom. The positive I Fig. 9 represents a chloroform-tube, in which a piece' of 



cotton- wool had been inserted with a view of ascertaining whether 

 any motion would be commuricated to it by the current. This 

 proved to be the case : but I do not attempt here to describe the 

 phenomenon. To the unassisted eye the discharge was extremely 

 brilliant ; it pas-ed in a column not quite straight, but in a 

 writhing, snake-ltke curve, with flaky stria; at intervals through 

 its length. When viewed in the mirror the strise were seen to 

 spread themselves out with slight, but iiTegular, proper motion. 

 With an increased battery-surface, or with a greater number of 



cells, but more notably with the latter, not only were the strife 

 lengthened, but from several of the long elementary stria; shorter 

 ones were thrown cut nearly at rii^ht angles to the former. These 

 were of short duration, and had great proper motion. The 

 general appearance of these compound stri,-e was that of branches 

 of fir trees, the twigs of which represented the permanent striEC, 

 and the leaves the secondary. 



{To be continued.) 



SOCIETIES AND ACADEMIES 



Paris 

 Academy of Sciences, Sept. 19. — M. Wurtzinthe chair. — 

 The president gave a welcome to the foreign members of the In- 

 ternational Congress of Electricity who were present, including 

 Clausius, Clifton, Du Bpis Reymond, Everett, Forster, Helirholtz, 



Kirchhofi, Melsens, Spottiswoode, .Siemens (William and Werner), 



Smith, Stas, Thomson, Warren De La Rue, and Wartmann. The 



following papers were read : — On the relative resistances that 

 should be given, in dynamo-electric machines, to the active 

 bobbins, the inductor electro-magnets, and the interior circuit 

 by Sir William Thomson. — On experiments made in 1826 on 

 electric currents by lightning far from the place of observation 



