METEOROLOGICAL INSTRUMENTS. 



THE instrumental observations which are recognised as indispen- 

 sable at properly furnished Meteorological Stations refer to the 

 following phenomena : 



Atmospheric Pressure. 



Temperature. 



Humidity. 



Precipitation. 

 Evaporation. 

 Atmospheric Motion, or Wind. 



In addition, other phenomena are occasionally made the subjects 

 of instrumental observation ; among these may be mentioned, 



Atmospheric Electricity. 

 Ozone. 



Specific gravity of Sea- water, as a branch of Maritime 

 Meteorology. 



These subjects will be treated in the order in which they have 

 been enumerated. It is hardly necessary to remark that the list 

 in question does not exhaust the catalogue of observations which 

 must be made in order to afford a complete record of the weather 

 at each station. 



More or less complete sets of instruments, showing the outfit of 

 meteorological stations, are exhibited by the Central Physical 

 Observatory of St. Petersburg, the Meteorological Office, and the 

 Meteorological Society. 



