300 The Standard of Weights, Measures, and Coinage. 



ards, and with each, other. They are also to report from time 

 to time the results of their examinations and experiments, 

 and to recommend such further changes, modifications, and 

 renewals of standards as they may see fit. In short, the Com- 

 missioners have undertaken an exhaustive inquiry into the 

 whole subject, of a most minutely scientific character. Up to 

 the present time, we believe, the preliminary official compari- 

 sons of the Standards of Avoirdupois and Troy weights only 

 have been effected. The errors in regard to the Avoirdupois 

 Standards, are found to be the greater of the two, and this 

 arises from the fact of their having been much more frequently 

 used. It is only by innumerable weighings, testings, calcula- 

 tions, and comparisons, that anything like absolute truth can 

 be arrived at. The changes of temperature in our variable 

 climate affect not only the dimensions, but the weight of all 

 metallic bodies. A sovereign, for example, held for a minute 

 between the finger and thumb, expands in size and increases 

 in weight. It imbibes heat and has moisture imparted to its 

 surface. Hence the changes. The same principle affects, more 

 or less, all simple or compound metallic substances. It is a 

 point, therefore, in the construction of standards, to employ 

 such admixtures of metal as are least influenced by atmo- 

 spheric variations. 



The Standard Commission, it is understood, are about to 

 institute comparisons of the remaining official standards of 

 " bullion-weight, capacity, length, and gas measures of 

 volume/' as well as to the re-verification of the standard of 

 length — the yard. This latter will be effected by a new micro- 

 metrical comparing apparatus of great delicacy. The appa- 

 ratus is to be adapted for longer measures than the yard, as 

 well as to its subdivisions. A totally new standard bar of 

 greater length than the yard, is indeed, in course of prepara- 

 tion, and this will answer a double purpose. Upon it will be 

 indicated not only the yard, with its subdivisions into feet and 

 inches, and the minute subdivisions of the latter, but the 

 French metre with its subdivisions also. This is the more 

 essential, since in very many of the mechanical and engineering 

 establishments of the kingdom, the metrical system of mea- 

 surement is constantly employed ; and the probability being 

 that in time the plan will be widely extended. 



In reference to the verification of measures of capacity, the 

 authorities of the Standards' Department have adopted an ela- 

 borate mode originally suggested by Captain Kater. Its main 

 feature consists in weighing the exact contents of each measure 

 — those contents being distilled water. In order to accom- 

 plish this effectually, accurate observations of the pressure and 

 the temperature of the atmosphere have simultaneously to be 



