LEGAL DEFINITION OF THE ELECTRICAL UNITS IN 

 THE UNITED STATES 



[Act Approved July 12, 1894] 



Be it enacted, etc., That from and after the passage of this act the 

 legal units of electrical measure in the United States shall be as follows: 

 FirxL The unit of resistance shall be what is known as the inter- 

 national ohm, which is substantially equal to one thousand million units 

 of resistance of the centimeter-gram-second system of electro- 

 Ohm 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 fourteen and four thousand five hundred 

 :iml twenty-one ten-thousandths grams in mass, of a constant cross- 

 sectional area, and of the length of one hundred and six and three-tenths 

 centimeters. 



*<cond. The unit of current shall be what is known as the inter- 

 national ampere, which is one-tenth of the unit of current of the centi- 

 meter-gram-second system of electro-magnetic units, and 

 Ampere is the practical equivalent of the unvarying current, which, 

 when passed through a solution of nitrate of silver in water 

 in accordance with standard specifications, deposits silver at the rate 

 of one thousand one hundred and eighteen millionths of a gram per 

 second. 



Third. The unit of electro-motive force shall be what is known as 

 the international volt, which is the electro-motive force that, steadily 

 applied to a conductor whose resistance is one international ohm. 

 Volt will produce a current of an international ampere, and is practi- 

 cally equivalent to one thousand fourteen hundred and thirty- 

 fourths of the electro-motive force between the poles or electrodes of 

 the voltaic cell known as Clark's cell, at a temperature of fifteen degrees 

 centigrade, and prepared in the manner described in the standard 

 specifications. 



Fourth. The unit of quantity shall be what is known as the inter- 

 national coulomb, which is the quantity of electricity trans- 

 ferred by a current of one international ampere in one second. 

 Fifth. The unit of capacity shall be what is known as the inter- 

 national farad, which is the capacity of a condenser charged 

 to a potential of one international volt by one international 

 coulomb of electricity. 



Sixth. The unit of work shall be the Joule, which is equal to ten 

 million units of work in the centimeter-gram-second system, and 

 which is practically equivalent to the energy expended in one 

 second by an international ampere in an international ohm. 

 r, " 705 



