JASI'ARY -I, lf<95.] 



SCIENCE. 



9 



Tliou nuMitiil moral orl), thou new, imlecil new, spir- 



itnal world, 

 The IVesent holtls thee not — for sueh vast growth as 



tliine, 

 For such unpanillcle<l (light as thine, such hrotnl as 



thine, 

 Tlie Future only hoUls thee and can hold thee.* 

 G. Brown Goode. 

 U. S. National Museum. 



LEGAL UNITS OF ELECTRIC 3IEASVIIE. 



It will, doubtless, be interesting to all 

 phyt^ic'ists, as well as to many in other de- 

 partments of seience, to know of the legali- 

 zation by Act of Congress, within the last 

 six months, of imits of electrical measure. 

 It is not necessary in these columns to go 

 into an exposition of the necessity for such 

 action on the part of the Government, nor 

 to refer to the enormous amount of capital 

 invested in the manufacture of instruments, 

 devices and machinery, the sole object of 

 which is the conversion of some form of 

 energy into electricity and the reconversion 

 of electricity into some form of energy. 

 The measurement of the enormous quanti- 

 . ties of electricity that have within the last 

 decade been produced and thus converted 

 has, up to a recent date, in all cases de- 

 pended upon the conventional acceptance 

 of units of measure which have for many 

 years been in use among scientific men, and 

 which originated in the necessity for such 

 units of measure in scientific investigations. 

 It is always wortli while to note, lu)wever, 

 that the great simplicity and perfection of 

 electrical measurement is due to the fact 

 that the science of electricity preceded the 

 art of its utilization. In this respect elec- 

 trical engineering has a very decided ad- 

 vantage over all other branches of engineer- 

 ing, for in all others the art preceded the 

 science, and the science, therefore, was 

 obliged to build itself upon the crude and 

 mostly unphilosophical principles that de- 

 veloped in the art. 



•Whitman, Leave;) of Grass. 



The fundamental units of electrical meas- 

 ure, nanu;ly, the ohm, the ampere and the 

 volt, have been in use among scientific men, 

 to the exclusion of all others, for more than 

 a decade, related as they are to the funda- 

 mental units — length, mass and time, which 

 are admirably adai)ted for use as the basis 

 of all electrical metrology. It has, how- 

 ever, long been recognized that much incon- 

 venience was caused in electrical discussion 

 bj- the lack of a few additional units, the 

 use of which would greatly fticilitatc mathe- 

 matical calculations and numerical state- 

 ments. The literature of the subject has 

 abounded, during the past ten years, with 

 suggestions as to these additional and de- 

 sirable units of measure, and various writers 

 have, from time to time, adopted such as 

 seemed to be necessary for their own use, 

 even giving them such values and such 

 names as were best in their judgment. It 

 was evident, therefore, that to prevent con- 

 fusion in electrical nomenclature it was de- 

 sirable to have an international agreement 

 as to these tmits, their value, their num- 

 ber and their names ; the demands for 

 this have grown very extensive in the last 

 few years, the result having now been 

 reached in the passage, by Congress, of a 

 law which seems to define and settle these 

 questions as far as the United States Gov- 

 ernment is concerned. 



All readers of this journal are, doubtless, 

 fiimiliar with the fact that as early as 1881 an 

 electrical convention, or congress, was held 

 in Paris for the purpose of trying to agree 

 upon definitions of the fundamental units of 

 electrical measure and their material repre- 

 sentations, in cases where mateiial repre- 

 sentations were possible. After much dis- 

 cussion, and not without very considerable 

 opposition, there was proposed at that time 

 a material representaticm of the ohm which 

 was known to be somewhat in error. The 

 real ohm must always be that defined by 

 the Coaimittee of the British Association 



