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A Scientific Test

A Scientific Test image
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Certaiu experiments that have. been quietly in progress in the physical laboratory of the university for the past year have resulted in a triumph for "Oíd Michigan," and a surprise for our English cousins. The physicists here have made a scientiflc touchdown. Those who cannot sympathize from a standpoint of science will make ready for three bheers and a tiger at all events, for the U. of M. has forstalled the British Association for the Advancement of Science in its official investigations, and has throttled a doubt that has long been a stnmblingblockto physicists the world over. It all goes to heap honors on the buff and bine. As the wise men have translated it for the ears of laity, the problem so long confronted lay in their inability to bring the ideal unit in electrical science to agree with the practical nnit as manifested in eleetrical force. The ideal unit was first fixed by the British Association for the Advancement of Science fnlly 30 years ago, and was confirnied by a congress of electricians atthe Expositiou Internationale D'Electricite, held in Paris in 1881. The name ampère was then given the ideal unit in honor of the great French physicist Ampère. Prof. Henry S. Carhart, now at the head of the physical department of the University of Michigan, was one of the jixrors present at the session of the congress. In 1884 Lord Rayleigh announeed the practical unit in terms of the electro-chemical equivalent of silver, or by the weight of silver the ampère would deposit by the process of electr.olysis in an hour. This unit was legalized by the United States congress in 1894, and soonfafterwards by order in council in England. Serious difficulties have arisen recently, since this practical unit was discovered to be too small by about one-tenth of 1 per cent. Griffiths' mechanical equivalent of 1893 measured by electrical means was found to exceed Rowland's mechanical equivalent measured by mechanical means. Such discrepanies were discussed by the committee on electrical standards, appointed by the British association f or the advancement of science convened in Toronto in 1897. Money was granted to carry on investigations that should redetermine the practical value of the ampère. Prof. Carhart was present at the convention. Upon bis return to Ann Arbor he instigated experiments in the physical laboratory that have now resulted in the redetermination of the ampère 's practical value. The English physicists have got their sleeves rolled up and are spending the British association's money getting ready to investígate. This work in the physical laboratory here wasjin progress almost a year before its successful accomplishment. The investigations were carried on unpretentiously ; even now the results have been published only inafewscientific periodicals in the gast. Prof. Patterson and Dr. Guthe, ofthe University of Michigan, directed the investigations, and, in consultation with Prof. Carhart, brought them to so successful an issue. Prof. Patterson and Dr. Guthe devised a new apparatus, which was constructed with painstaking care. For measurements of time the unirersity observatory was brought into requisition. The physical department has a ! unit of weight in exact correspondence with the legal standards in the bureau of weights and measures at ! ton. A standard of length has been furnished the deptirtment by the late Prof. V. A. Rogers. The process redotermmed the eleetroehemieal equivalent of silver and exactly explaiued the discrepaneies which had existed between the resulte of Grifñth's aud Rowland'sinvestigations. It proved that the practical ampère heretofore employed was abont ouetenth of oue per cent too small. Tliis restilt will change by the same percentage the electromotive foree of the Clark cell, which is an accepted standard of electric pressure. The resnlt of Dr. Guthe and Prof. Patterson and Carhart's work, has been snbmitted to the American Association for the Advancement of Science which highly commended it and has received gratifying praise from the most (listinguished scientists. In the meantime in Great Britain the committee on electrical standíirds is gettiug to