COMMITTEES ON BEHALF OF THE GOVERNMENT 313 



COMMITTEE TO PRESCRIBE AND PUBLISH SPECIFICATIONS 

 FOR THE PRACTICAL APPLICATION OF THE DEFINITIONS 

 OF THE AMPERE AND VOLT. 1894 



It will be recalled that the Academy sent delegates in 1884 to 

 the International Congress of Electricians at Paris. At this 

 congress the " legal ohm " or " congress ohm " was established, 

 having for its determination the resistance of a column 

 of mercury 106 centimeters long. It was considered both at 

 that time and subsequently that this length was not the proper 

 one and for the further consideration of this and other matters 

 connected with electrical units an international electrical congress 

 was held in Chicago in 1893. On this occasion the ohm known as 

 the " international ohm " was determined upon, having as its 

 basis the resistance of a column of mercury 106.3 centimeters 

 long. The " volt," " ampere," " henry " and other units were also 

 fixed. 



In the year following an act was passed by the Congress of 

 the United States, defining the various units in accordance with 

 the decisions of the electrical congress. These comprised the 

 ohm, the ampere, the volt, the coulomb, the farad, the joule, the 

 watt and the henry; the last, as is well known, named in honor of 

 Joseph Henry, the first Secretary of the Smithsonian Institution 

 and second President of the National Academy of Sciences. 



The act referred to, which was approved on July 12, i894, 186 

 contained the following provision: 



" Sec. 2. That it shall be the duty of the National Academy of Sciences to 

 prescribe and publish, as soon as possible after the passage of this Act, such 

 specifications of details as shall be necessary for the practical application of the 

 definitions of the ampere and volt hereinbefore given, and such specifications 

 shall be the standard specifications herein mentioned." 



For some reason which is not apparent, the Act did not come 

 to the attention of the President until the last day of October. 161 

 On November 6, he applied to the Secretary of State for an 

 authentic copy, and received the same on November 9. 



198 Stat. at Large, vol. 28, p. 101, 53d Congress, zd Session, chap. 131. See also Rep. Nat. 

 Acad. Sci. for 1894, P- 395 a ls for 1895, p. 7. 

 167 See Rep. Nat. Acad. Sci. for 1894, P- 4- 



