Electricity. 341 



them as due to the vibrator}" state of the molecules at the surface of 

 electrified substances, accompanied by a -more or less abundant emission 

 of material particles detached from this surface, according to the condi- 

 tions in which the electrified substances are placed in reference to the 

 surrounding medium. The phenomenon of the aigrette ( or brush of 

 down ) is a characteristic manifestation of this emission of ponderable 

 matter. The aigrette is always produced in a greater or less degree on 

 different points of a strongly electrified substance ; the least wrinkle in 

 the surface will occasion it. This phenomenon then reveals the state of 

 continual discharge in which a substance may be when charged with 

 static electricity." "The earlier electricians, principally Boyle and 

 Hankshee, had already allowed that material effluvium escapes from 

 electrified substances. This idea appears to us to be still correct at the 

 present time by adding to it the vibratory molecular motion of the sur- 

 face of these substances." " It may be also said that this emission be- 

 comes more evident the nearer the electrified substance chances to be to 

 another substance not electrified, which serves, in some degree, as target 

 for the projectiles formed by the molecules from the electrified sub- 

 stance. " " To sum up in a few words the views herein stated; we 

 think that electricity may be considered as a movement of ponderable 

 matter a movement of transport given to a very small mass of matter 

 impelled to an extreme velocity, when there is a question of electric dis- 

 charge and a very rapid vibration of the molecules of matter when 

 touching its transmission to a distance in a dynamic form or its mani- 

 festation in a static form on the surface of substances. " (Gaston Plante. ) 

 There are numerous analogies between the action of electricity and of 

 other mechanical motion at a high tension, some of which may be men- 

 tioned. ' < The mechanical calorific and chemic action produced at the 

 same time by an electric current of a certain tension, on the surface of 



FIG. 146. Engraving by Electricity. 



glass, which has led to engraving on glass by electricity, may be com- 

 pared with the action exercised" by the "sand blast" on glass, in 

 which glass is engraved by a very fine jet of sand shot forth under strong 

 pressure, which has been in use for many }^ears in this country: The 

 process of electrical engraving on glass is briefly as follows : The glass 



