122 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



which is caused by the mechanical pressure which is oper- 

 ative. 



Fuller has communicated to the Physical Society of Lon- 

 don a description of a new form of electrical machine, called 

 an electric multiplier, which is essentially a double-acting 

 electrophorus. It consists of a vulcanite quadrant, ove? 

 which electricity is distributed by a metallic arm, carrying 

 needles which swing over it, the charge being removed from 

 the other side by a similar set of points attached to an arm 

 connected to earth. Two quadrantal metal plates being 

 now automatically brought in contact with the vulcanite, 

 receive a strong charge, which becomes free on removing 



CD CD * CD 



again the plates from the vulcanite. 



Ilagenbach has made some experiments in the university 

 of Basle to ascertain the effective performance of one of the 

 smaller Gramme magneto-electric machines used as a source 



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of light for lecture-room purposes. He finds as follows: 



The work done at 1800 revolutions was 90 kilogrammeters, 

 or about 475 candles to the horse-power. The machine was 

 driven by a water motor, and the light cost nearly seventy 

 cents per hour. As to give the same light from a battery 

 would require from seventy-two to eighty Bunsen cells, the 

 light from the machine is much the cheapest. 



Anthony has also given some measurements of the per- 

 formance of a Gramme machine constructed in the work- 

 shop of the Cornell University. According to the results 

 given, the machine, when making but about 500 rotations, 

 gave a light of 1600 candles; but as, unfortunately, the 

 horse-power consumed is not stated, no opinion of the effi- 

 ciency of the machine can be formed. Further experiments 



are promised. 



3. Velocity. 



A paper has been published by Wand on the propagation 

 of electricity in cylindrical conductors, which is an extended 

 mathematical discussion of the whole subject. He finds (l) 



