ON STANDARDS FOR USE IN ELECTRICAL MEASUREiMENTS. 121 



A. Schrader, Regierungsrath, Mitglied des kaiserl. Patentamts, Berlin. 



Dr. Ernst Voit, Professor an der technischen Hochschule, Miinchen, 

 Schwanthalerstrasse 73-3. 



Dr. Otto Lummer, Mitglied der physikalisch-technischen Reichsanstalt, 

 Charlottenburg, Berlin. 



Rejyresentinri Mexico. 

 Augustin W. Chavez, city of Mexico. 



Representing Austria. 



Dr. Joliann Sahulka, Technische Hochschule, Wien. 



Representing Siuitzerland. 



A. Palaz, Professeur, Lausanne. 



Rene Thury, Ingenieur, Florissant, Geneve. 



Representing Sweden. 

 M. "Wennman, ByrSchef i Rougle Telegrafstyrelsen, Stockholm. 



Rej)resenting British North America. 



Ormond Higman, Electrician, Standards Branch, Inland Revenue 

 Department, Ottawa. 



His Excellency Dr. H. von Helmholtz was made Honorary President 

 of the Congress ; Dr. Elisha Gray, of Chicago, was Chairman of the 

 General Congress ; and Professor H. A. Rowland, of Baltimore, was 

 President of the Chamber of Delegates. 



Meetings of the Chamber continued during six days, at the end of 

 which its members unanimously agreed in the adoption of the following 

 resolution :^ 



Resolved, That the several Governments represented by the delegates 

 of this International Congress of Electricians be, and they are hereby, 

 recommended to formally adopt as legal units of electrical measure the 

 following : As a unit of resistance, the international ohm, which is based 

 upon the ohm equal to 10^ units of resistance of the C.G.S. system of 

 electro-magnetic units, and is represented by the resistance offered to an 

 unvarying electric current by a column of mercury at the temperature of 

 melting ice 14'-1521 grammes in mass, of a constant cross-sectional area 

 and of the length of 106 '3 cm. 



As a unit of current, the international ampere, which is one-tenth of 

 the unit of current of the C.G.S. system of electro-magnetic units, and 

 which is represented sufficiently well for practical use by the unvarying 

 current which, when passed through a solution of nitrate of silver in 

 water, and, in accordance with accompanying specifications,' deposits 

 silver at the rate of O'OOlllS of a gramme per second. 



' In the following specification the term silver voltameter means the arrange- 

 ment of apparatus by means of which an electric current is pa.ssed through a 

 solution of nitrate of silver in water. The silver voltameter measures the total 

 electrical quantity which has passed during the time of the experiment, and by 

 noting this time the time average of the current, or, if the ctirrent has been, kept 

 constant, the current itself, can be deduced. 



la employing the silver voltameter to measure cturrents of about one ampere the 

 following arrangements should be adopted : — 



The kathode on which the silver is to be deposited should take the form of a 



