374 Intelligence and Miscellaneous Articles. 



another whenever it ceases. In short, this is a completely automa- 

 tic candle requiring only a very simple support ; the lighting, the 

 fixing at the desired distance, and the maintenance of the arc at the 

 two points result spontaneously from the electromagnetic forces, 

 which take upon themselves the whole of the work. It is moreover 

 evident that these forces are proportional to the square of the 

 intensity of the current, and can always be rendered sufficient ; it 

 is only a question of construction. M. Fernet proposed to place 

 the carbons one in the prolongation of the other, and to take 

 advantage of their repulsion to separate them. This repulsion was 

 but feeble ; in the solution proposed by me the action is more 

 energetic and becomes efficient. 



When the action of the rectangle is sufficient, the arc, spread out 

 and driven beyond the points, has the appearance of a gas-flame ; 

 its length is increased. From this results a greater expenditure of 

 electromotive force ; and the amount of light is not increased pro- 

 portionately ; for it is known that, if the arc attains a very high 

 temperature, it does not possess a brightness comparable with that 

 of the carbon points. But on remarking that the arc was projected 

 outside, I conceived the idea of receiving it upon lime, magnesia, or 

 zircon, like the oxyhydrogen-flame in the Drummond lamp. The 

 arc is crushed by this obstacle, keeps a constant length, and, far 

 from consuming more electromotive force, it saves a notable portion, 

 because it springs in a highly heated and more conductive space. 

 On the other hand, the light, instead of disappearing skywards, 

 where it is useless, is reflected toward the ground ; this will permit 

 the electric lamp to be placed at a great elevation, out of the usual 

 direction of looking. Besides, the ' light is altogether changed : it 

 is no longer violet, but white ; it even appears greenish yellow by 

 contrast and by the augmented intensity of the green lines of the 

 lime; and, finally (the most valuable result of all), it is at least 

 three times as intense as without the cap of lime. In truth, that 

 cap must not rest upon the points ; for these will fuse and pene- 

 trate the lime, and the arc will find its path inwards and shine no 

 more. This defect can easily be remedied. 



The fusion of the lime proves that the arc thus projected by a mag- 

 netic effect is capable of considerably heating all bodies ; it is a real 

 blowpipe — probably the most powerful of nil. I recommend it to 

 chemists and physicists. I shall myself have to entertain the 

 Academy with the powerful effects that can be obtained from it. — ■ 

 Comptes Rendus de V Academic des Sciences, March 17, 1879, 

 t. lxxxviii. pp. 541-544. 



ON THE ELECTRICAL PERFORATION OF GLASS. 

 BY PROF. A. VON WALTENHOFEN. 

 In connexion with his experiment described in 1866, and with a 

 treatise referring to it, by E. Mach and S. Doubrava, just published, 

 the author describes the following additional experiments: — 



A thin glass plate having upon it ever so small a drop of 

 stearine, introduced into the path of the spark of an electrical 



