INDUSTRIAL PROGRESS DURING THE YEAR 187G. Ixvii 



tee. This error consists principally in the omission from his equa- 

 tions of the coefficient of self-induction. Stoletow, in a subsequent 

 note, while admitting that the error exists, and that its correction 

 will tend to approximate the results, clearly shows that the error is 

 entirely too small to extinguish the two per cent. 



Wilson has contrived an ingenious method of attaching a mirror 

 to a galvanometer needle so that the angular motion of the beam of 

 light reflected from it shall be the same as that of the needle. For 

 this purpose the light passes vertically upward to the mirror, which 

 is fastened directly below tlie needle, and at an angle of 45 to its 

 plane of oscillation. 



Edlund has observed a fact of great importance to his theory of 

 electricity, i. e., the fiict that the resistance of a conductor varies 

 with the motion of this conductor, being lessened when the con- 

 ductor and the current move in the same direction, and increased 

 when the directions of the motion are opposite. In Edlund's theory, 

 in which electricity is only the flow of ether through bodies, the 

 strength of the current is measured by the mass of the ether which 

 flows throuo-h the cross-section of the conductor in a unit of time. 



Fuclis has proposed to use the electrometer as an instrument for 

 measuring current strength, polarization, and resistance. In his 

 experiments he employed a gold-leaf electrometer in communication 

 with a dry pile. By combining this with the compensation method 

 of Poggendorft', the results were satisfoctory. 



Fleming has made additional experiments to prove the position 

 assumed in his paper read at the British Association and objected 

 to by Rowland, i. e., that the electro-motive force developed by the 

 motion of an electrolvte throuu'h a strong magnetic field eflects tlie 

 decomposition of this electrolyte. He now shows that the facility 

 of polarization of the plates is unaffected by the aeration of the 

 liquid, and that the cause of this i3olarization can be removed from 

 the plates mechanically. 



Becquerel has published an important paper on the determination 

 of the chemical force exerted by two solutions upon each other by 

 means of tlie electro-motive force developed. The method is sug- 

 gestive, especially in its physiological relations, since the strength 

 and direction of the electro-motive forces in living beings are the 

 foundations upon which rest not only all the phenomena of nutrition, 

 but also those of life itself. 



Dufct has experimented upon the electric conductivity of pyrite. 

 He finds that this constant is very variable with different speci- 

 mens, owing, undoubtedly, to want of homogeneity in them. Wliilc 

 crystals from Traversella had a resistance varvino- from 750 to 4000 

 times that of mercury, those from Deville, more homogeneous, had 

 a resistance only seventy-five times that of this metal. The results 

 obtained show also that in a given crystal the resistance is constant 



