664 



MR R. C. MOSSMAN ON 



twice a day, at 10 a.m. and 9 p.m. The barograph and thermograph were also timed 

 at the same hours. 



Eye Observations {Table X.). 



Barometric Pressure. — The pressure observations are given reduced to 32° and 

 sea-level, the following condensed table showing the corrections applied for each 5° of 

 air temperature and half-inch of pressure : — 



Table for reducing Readings of Achariacli Barometer, 150 Feet above Mean Sea-level, to Sea-level. 





10° 



15° 



20° 



25° 



30° 



35° 

 •172 



40° 



45° 



50° 



55° 



30-5 



•181 



•179 



•177 



175 



•174 



•171 



•169 



•168 



•167 



300 



•178 



•176 



■174 



•172 



•171 



•169 



•168 



•166 



•165 



163 



29-5 



•17ft 



173 



•171 



•169 



•168 



•166 



•165 



•163 



•162 



•161 



29-0 



•172 



•170 



■168 



•166 



•165 



•163 



•162 



161 



•160 



•158 



28-5 



•169 



•167 



•165 



163 



•162 



•161 



•160 



•158 



•157 



•155 



Interpolated readings deduced differentially from the Richard barograph are 

 entered in brackets, and although it was not possible to ensure the same accuracy for 

 these values as would have been the case otherwise, yet they should not possess a 

 large probable error. 



Temperature and Humidity. — The air temperature, except on a few days at 2 p.m., 

 is from the eye' readings in the Stevenson screen. Interpolated values are deduced 

 from the corrected thermograph values. The interpolated wet-bulb temperatures have 

 been calculated from the relative humidity and air temperature. The maximum and 

 minimum thermometers, along with the maximum in sun and the minimum on grass, 

 were read and set at 9 p.m. The highest and lowest values in each month are 

 indicated by bold type. 



The relative humidity and vapour pressure have been taken from Glaisher's Tables, 

 7th edition (London, 1885), or from the Hygrometrical Tables, based on Glaisher's 

 work, printed by authority of the Meteorological Committee, 1876, and reprinted 

 in 1882. 



In a few exceptional cases of unusually dry atmosphere the relative humidity and 

 vapour pressure were computed by means of the factors given in Part IV. of Glaisher's 

 Tables, 7th edition. 



Wind Direction and Force. — The wind direction is true, and the force is estimated 

 on the Ben Nevis scale of 0-12. After 2nd December a Dines pressure tube 

 anemometer was in use, the results of which are summarised in the general tables, and 

 the indications of this instrument have also enabled me to interpolate missing 

 observations when, as was often the case, it showed that a complete calm had prevailed 

 between the preceding and succeeding observations. 



