FUNDAMKNTAL UNITS OF MEASURE. 141 



found impracticable to reproduce it, as had been intended, by the use 

 of a penduhiiii, and accordingly a new standard was prepared under 

 the direction of Mr. Shcepslumks from a half dozen excellent copies of 

 the destroyed standard which were available. This Avas legalized by 

 an act of Parliament in IS,"*, and is the imperial standard yard of Great 

 Britain to-day. It is a line measure, made of bronze, the total length 

 being 38 inches and the cross section 1 inch scpiare. At the time it was 

 prepared several copies were produced, one of which, known as Bronze 

 No. 11, is in the U. S. ofliceof weights and measures at NN'ashington. 



To recur now to standards of length in the United States, it is 

 necessary to repeat the often-published statement that although the 

 Constitution authorizes Congress to establish a systein of weights and 

 measures, it has never exercised this authority except in the matter of 

 legalizing the metric system in 1800. The weights and measures in use 

 in the colonies before the Revolution were almost entirely those of 

 Great Britain, and they continued in use without special legalization 

 for a long time after independence was declared. The first Superin- 

 tendent of the Coast and Geodetic Survey, Mr. Hassler, requiring an 

 accurate standard of length in the operations of that liurcau, obtained 

 from Troughton, of London, in 1814, a brass bar about 82 inches long, 

 2-5 inches wide, and one half inch thick. Thisbar was a direct descend- 

 ant of the Bird standard of 1700, a number of copies of which had 

 been made by Troughton. 



ll being necessary for the Executive Departments of the Government 

 to have some standards of weiglit and measure properly authenticated, 

 for the jHirpose of levying taxes, duties, etc., this bar, or rather one 

 particular yard of it, from the twenty- seventh to the sixty-third inch, 

 was adopted as the standard of length. It was supposed to be precisely 

 equal to the British standard at a temperature of 02° p. A direct 

 comparison with the copies of the new imperial yard of 1855, however, 

 showed that it was too long at that temperature, and this fact gave 

 rise to the idea which found its way into scientific literature that the 

 English and American yards were different, the latter being the longer. 

 The action taken in the oftice of weights and measures was simply to 

 change the temperature at which it was a standard, so as to bring it 

 into {igreement with the English yard. As a matter of fact its use as a 

 standard was practically discontinued, and the bronze copy of the 

 imperial yard was accepted in its ])lace, together with another copy of 

 this yard made of Low Moor iron and so designated. 



It will thus be seen that, as far as the Government is concerned, we 

 have followed the English in the matter of standards of length, and 

 their yard and ours have always been as nearly as practicable iden- 

 tical. 



The same is essentially true in regard to the standard of mass. 

 There is an important difference, however, in that Congress did, in 

 1828, legalize a standard Troy pound for purposes of coinage. This 



