ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. Each 

 of the scientific bureaus in Washington has a representative authorized to for- 

 ward such material to this journal and abstracts of official publications should 

 be transmitted through the representative of the bureau in which they originate. 

 The abstracts should conform in length and general style to those appearing in 

 this issue. 



PHYSICS.— TAe histonj of Ohm's law. J. C Shedd and M. D. Heesey. 

 . Pop. Sci. Mo., 83, 599-614, December, 1913. 



The earlier part of this paper gives an outline of the experimental de- 

 velopment of Ohm's law in the hands of Cavendish and others using the 

 static discharge; of Barlow, who, using the steady current from a voltaic 

 pile, concluded that the resistance of a conductor varies with the square 

 root of its length; of Cumming, who was led to this same conclusion; of 

 Davy, who discovered that wires having the same ratio of length to cross- 

 section offered the same resistance; of Becquerel, who was the first to 

 show that the resistance of a wire varies directly as the length and in- 

 versely as the cross-section; and finally in the hands of Ohm himself, 

 who, publishing first a radically incorrect relation, gradually arrived at 

 the present complete form of the law which bears his name. 



The latter part of the paper endeavors to trace the sequence of ideas 

 in Ohm's mind, and also to explain the origin of the misconceptions re- 

 garding his work which prevailed for so many years among scientific 

 men. M. D. H. 



'PHYSlC^.—ThePentajie Lamp as a working standard. E. C. Critten- 

 den and A. H. Taylor. To be published in the Bulletin of the 

 Bureau of Standards and in the Transactions of the Illuminating 

 Engineering Society. 

 The best standards of candlepower are electric incandescent lamps, 

 but it is not always practicable to use them. Of the various flame 

 standards the Harcourt 10-candle pentane lamp appears to be the best 

 for general use. This lamp has the disadvantages of being large and not 

 easily portable, of using fuel which is expensive and somewhat dangerous, 

 and of requiring more air than ordinary ventilation will supply, but in 

 spite of these faults its use is increasing rather rapidly. 



The candle power is not usually exactly ten, and the exact value 

 must be determined by a photometric test. The intensity is affected 



