160 RESEARCH 



and verification of standard meteorological and mag- 

 netic instruments was ' one of the great objects ' 

 of the observatory. The standard thermometer 

 was perhaps the most noteworthy example. The 

 Committee reports in 1851 : 



' The standard thermometer, which M. Regnault 

 kindly undertook to supply, has been received at 

 the observatory, together with apparatus for 

 verifying the freezing- and boiling-points. This 

 verification has been made under the superintendence 

 of a sub-committee, consisting of Mr. Gassiot, Dr. 

 Miller, and Colonel Sabine, with most satisfactory 

 results. . . . The Committee is able to report that 

 the observatory may now be considered to possess a 

 standard thermometer, with which other thermo- 

 meters designed to be used as standards may be 

 advantageously compared . ' 



John Welsh became superintendent of the 

 observatory in 1852, and from then until his death 

 in 1859 he substantially extended its various acti- 

 vities. The verification of thermometers, barometers, 

 and other instruments developed into a considerable 

 business : in the period 1854-69 over 11,000 

 thermometers, nearly 2000 barometers, and nearly 

 2500 hydrometers were verified, and a limited 

 number of the standard thermometers were actually 

 constructed at the observatory. Many other instru- 

 ments, principally magnetic, were verified, and in 

 many instances instruction in their use was given. 

 The observatory thus assisted in the equipment not 

 only of Government departments at home, together 

 with numerous private establishments, but also of 

 institutions and individuals in many parts of the world, 



