WHOLE VOL. NOTES. ASIA 1 5 



CEYLON 



GENERAL NOTES 

 Authority. 



Colombo Observatory, Ceylon. 



(1) The values of barometric pressure at Nuwara Eliya from 1921 

 include a gravity correction of — 0.069 m - to correct readings in Lat. 

 6° 59' and at altitude 6200 ft. to the normal 45 ° standard. 



(2) Values prior to 1921 that appear in World Weather Records 

 have been corrected for the direct latitude difference of gravity, but 

 not for the altitude modification of the same. There is thus a case 

 for decreasing them all by an amount of the order of .009 in. It is 

 extremely doubtful, however, whether such a correction would be 

 desirable, as it would make no difference to the intercomparison be- 

 tween the old results, and the uncertainties in the index errors of the 

 old results are probably considerable. 



(3) The barometer at Nuwara Eliya was out of action from 1922 

 to 1928, after which it was restarted at a different altitude, 6170 ft. 

 The values of barometric pressure from 1928 onwards have not been 

 reduced to 6188 ft. 



(4) A change has recently been made in the method of exposing 

 thermometers in Ceylon. Instead of the open thermometer sheds 

 formerly in use, large-size Stevenson screens are now used. (For 

 particulars see Ceylon Journal of Science, Section E, vol. 1, pt. 2, 

 p. 153.) The screens give values systematically lower than the sheds, 

 especially for maximum values. 



(5) The temperature figures at Colombo from 1921 to 1927 in- 

 clusive, at Trincomalee from 192 1 to 1927 inclusive, at Hambantota 

 from 1921 to May 1929 inclusive, and at Nuwara Eliya from 1921 

 to 1928 inclusive have been corrected to equivalent screen values by 

 means of tables, which can be supplied if required. These tables have 

 been compiled from direct simultaneous comparisons between shed 

 and screen readings at the various stations. 



(6) The remainder of the temperature figures have been taken 

 direct from screens. The corrections from shed to screen are usually 

 less than a degree, except at Trincomalee, where they vary from 

 1.9 F. in April to 0.7 F. in June and July. 



(7) At Hambantota, the height of the barometer was 64 ft. until 

 January 1925 ; from February 1925 the barometer was at a height 

 of 61 ft. All readings before February 1925 were reduced to 61 ft. 

 by adding .003 in. 



