512 



XIII. NOTES ON THE RECORDS OF SUNSHINE AND ON THE 

 OBSERVATIONS OF CLOUD. 



BY 



R. H. CURTIS. 



INSOLATION is a factor of the Antarctic climate to which very little attention has been paid by previous 

 expeditions. A sunshine recorder formed part of the instrumental outfit of the " Southern Cross " 

 Expedition which wintered at Cape Adare, but as the instrument was not adapted for use in high latitudes 

 where in summer the sun is continuously above the horizon, the record obtained was necessarily very 

 incomplete. 



For the present Expedition a modification of the Campbell-Stokes burning recorder, enabling it to 

 receive a continuous record of sunshine throughout the entire 24 hours, was designed at the Meteorological 

 Office in consultation with Sir GEO. G. STOKES and constructed by Mr. HICKS. When this instrument 

 was arranged for summer use, the bowl formed a complete circle, but in the spring and autumn months 

 the northern half of the bowl could be removed in order to afford to the lens a perfectly unobstructed 

 "view of the sun" when at its lower altitudes above the horizon (figs. 1, 2). 



This recorder was not set up until September 14, 1902, by which date the sun had already attained a 

 considerable meridian altitude, and it was finally dismounted at the middle of February, 1904. The record 

 embraces therefore one complete spring, summer, and autumn ; nearly the whole of a second spring ; and 



Sunshine recorder for use in Polar latitudes. 



Fig. 1 Showing front portion of the bowl removed Fig. 2. Showing the complete bowl with sphere and 



for use in spring and autumn. A short card is shown card in place, for recording sunshine throughout the 



in position in the upper part of the belt. 24 hours. 



three and a half months out of the four comprising the second summer. Unfortunately, a total of 23 cards, 

 representing 23 days' records, were missing when the Expedition reached England, and the total amounts 

 of sunshine recorded for September, October, and November, 1902, and for September and October, 1903 

 the months to which most of the lost cards belonged are in consequence probably somewhat smaller 

 than they should have been. 



The earliest date on which a record was obtained was September 3, and the latest April 14; but the 

 sun appeared above the horizon on August 21, and did not finally disappear for the winter until about 

 April 24; and it is not clear from the records whether the absence of cards for the clays intervening 



