10 



SCIENCE. 



[N. S. Vol. I. No. 1. 



for the Advancement of Science, and any 

 material representation which may be 

 adopted should only be considered as an 

 approximation to this. It was first agreed 

 that this theoretical ohm should be re^jre- 

 sented by the resistance offered to an un- 

 varying current of electricity bj^ a column 

 of mercury one square millimeti'e in cross 

 section, and one hundi-ed and six centime- 

 tres in leng-th, at a definite temperature. 

 Even at the time of the acceptance of this 

 ohm it was well known that the length of 

 this column was nearlj^ three millimetres 

 too SEiall to correctly represent the ohm of 

 the British Association Committee. This 

 result had been estabUshed by investiga- 

 tions by Rowland in this country, and by 

 other experimentalists in Europe. In con- 

 sequence of the inaccuracj^ of this first 

 material representation of the ohm it did 

 not meet with much favor, although it was 

 quickly taken up among practical men, and 

 resistance coils in great numbers were wound 

 in accordance with this definition, being 

 generally, but incorrectly, known as the 

 ' Legal Ohm.' I do not know that this 

 unit was ever adopted by any govern- 

 ment, or even by any municipal corpora- 

 tion. 



During the last ten years there has been 

 a continual agitation of this question, re- 

 sulting in the determination to go over the 

 whole subject again, with a view to defining 

 the fundamental units and adding such 

 other units as might be desirable and neces- 

 sary, at an International Congress to be 

 held at Chicago in 1893, in connection with 

 the World's Fair. The inception and or- 

 ganization of this Congress was largely due 

 to the American Institute of Electrical En- 

 gineers and to local societies in the city of 

 Chicago. Its history is so well known that 

 it is only necessarj^ to refer to it very 

 briefly. In order to avoid errors which are 

 likely to arise in the consideration of a very 

 important siibject by a very large assem- 



blage, it was agreed that the question of 

 units should be referred to a body wliich 

 was within, and formed a jjart of, the gen- 

 eral International Congress, and which was 

 known as the Chamber of Delegates. In 

 this Chamber of Delegates the number of 

 representatives from the different nations 

 was limited ; five each were allotted to the 

 United States, Great Britain, France and 

 Germany, three to Italy, and to the other 

 nations a smaller number. Most of the 

 jirincipal delegations were full on the assem- 

 bling of the Chamber, and the total number 

 of persons was about thii-ty. Dailj' sessions 

 were held during the week of the Interna- 

 tional Congress, and many hours aside fi-om 

 these sessions were occupied bj' special com- 

 mittees in the discussion and develojDment 

 of the various subjects which came before 

 the Chamber to be acted upon. 



In reference to the personnel of this 

 Chamber, it may be well to say that the 

 delegates from foreign countries were ap- 

 pointed by their respective governments 

 and presented regular authenticated com- 

 missions, and that the representatives of 

 the United States received their authority 

 fi-om the Secretary of State in a commis- 

 sion which he prepared after the names of 

 the five j)ersons selected had been recom- 

 mended to him by a vote of about sixty or 

 seventy of the leading electricians of the 

 country, who had been invited to join in 

 this ballot by the Chairman of the Execu- 

 tive Committee for the organization of an 

 International Congress. The five names 

 receiving the greatest number of votes 

 were recommended to the Secretary of 

 State for appointment as representatives of 

 the United States. A list of the delegates 

 present and taking an active part in the 

 deliberation of the Chamber is given here- 

 with : 



liepi-cseniing the United States. 

 Professor H. A. Rowland, Johns Hopkins Univer- 

 sity, Baltimore, Md. 



