1862.] 329 



XV. Cubic surface of the fifth class with a uuiplanar node. 



Species XV. 1. 

 XVI. Cubic surface of the fourth class with four proper nodes. 



Species XVI. 1, 2, 3. 

 XVII. Cubic surface of the fourth class with two biplanar and 



one proper node. Species XVII. 1, 2, 3. 

 XVIII. Cubic surface of the fourth class with one biplanar and 



two proper nodes. Species XVIII. 

 XIX. Cubic surface of the fourth class with a biplanar and a 



proper node. Species XIX. 1 . 

 XX. Cubic surface of the fourth class with a uniplanar node. 



Species XX. 1. 

 XXI. Cubic surface of the third class with three biplanar nodes. 



Species XXI. 1, 2. 



XXII. Ruled surface of the third order and the third class. 

 Species XXII. 1, 2, 3. 



IV. "Experimental Investigations on the Stratified Appearance 

 in Electrical Discharges." "Effect obtained by varying 

 the Resistance." By JOHN P. GASSIOT, F.R.S. Received 

 December 11, 1862. 



1 . In the ' Proceedings of the Royal Society,' May 26, 1859, 1 have 

 stated that, "on attaching the terminals of my water -battery (Phil. 

 Trans. 1844, p. 39) to the wires of a carbonic acid vacuum-tube, 

 inserted about 2 inches apart, I obtained a stratified discharge 

 similar to that of an induction coil." 



2. The battery remained as it was originally constructed, consist- 

 ing of 3520 pairs of copper and zinc cylinders inserted in glass cells. 

 As the rain-water with which each cell had been from time to time 

 filled evaporated, they were again charged: this process of evaporation 

 and recharging continuing for several years, during this lengthened 

 period the battery was three or four times cleaned by dusting and 

 wiping the cells, boards, and slips of glass on which the cells rested ; 

 but the constant deposition of dust and moisture had so far reduced 

 the static effects of the battery, that this year it would scarcely elicic 

 a spark of about s^Vuln of an inch in air between the plates of mv 



