NATUKAL PHILOSOPHY. 141 



bowed coil. The conducting points attract off the atmospheric electricity, and 

 convey it safely to the earth, while the galvanic current passes freely to the 

 instrument. 



M. Becquerel, of France, has also recently presented to the French Academy 

 an apparatus, invented by M. Bianchi, which is intended to preserve tele- 

 graphic apparatus from the disturbing influence of atmospheric electricity. It 

 consists of a metallic sphere, traversed by the circuit wire, and kept in the 

 center of another glass sphere, formed of two hemispheres united by a broad 

 copper ring, armed at its inside with equi-distant points directed toward the 

 center of the metallic sphere, and approaching within a short distance of its 

 surface. The two hemispheres end in sockets, into which the connecting wire 

 passes and is cemented. The lower part of the copper ring is provided with 

 a metallic stop-cock, which permits a vacuum to be made hi the apparatus, 

 and kept in it if it be thought necessary. This stop-cock has a screw-thread 

 which is to receive a metallic rod designed to put the metallic armature into 

 direct connection with the earth, while the circuit wire, and the sphere which 

 forms part of it, are completely insulated. All the atmospheric electricity 

 which comes upon the conducting wire of the telegraph is transmitted to the 

 ground through the points with which the ring is armed. 



Such an apparatus is to be erected at each station ; experiment has proved 

 to the author that when the discharge of a battery of eight jars is passed into 

 a telegraphic conductor provided with this apparatus, the dynamic current is 

 not affected, and all the statical electricity passes into the earth, under the 

 influence of the points. Comptes Rendus. 



ox THE " STRATIFICATION" OF ELECTRIC LIGHT. 



Before the Paris Academy a paper has been read by M. Gaugain on the 

 stratification of electric light,, as he calls that disengagement of differently 

 colored light we see produced when an electric spark is transmitted through 

 gas, rarified by the air-pump. Of all the phenomena produced by the pass- 

 age of electricity through rarefied mediums, perhaps the most singular is 

 visible hi the residuary vapors of alcohol, or the essence of turpentine, where 

 the luminous nebulosity, caused by the passage of electricity, is divided per- 

 pendicularly to the direction of the current, in parallel sections, separated 

 by dark spaces. These alternatives of light and obscurity were thought to 

 point out the existence of an undulatory phenomenon, and some philosophers 

 hoped it would enable them to detect the still hidden mechanism of the 

 propagation of electrical actions. This hope M. Gaugain dissipates. He 

 especially examined three different mediums air, exempt from vapors ; the 

 vapor of essence of turpentine ; and mixtures of variable proportions of ah* 

 and the vapor of essence of turpentine. It is generally admitted that the 

 phenomena of stratification may be produced in air exempt from vapor ; for, 

 when the observer uses a globe in which turpentine, alcohol, or any other 

 substances suitable for the formation of strata have been used, the strata are 

 constantly obtained, even after the air in the globe has been several tunes 

 renewed. Nevertheless, M. Gaugain affirms these strata are not due to the 



