208 



CORAL AND ATOLLS 



The Pulu Tikus observations differ somewhat markedly 

 from those that have previously been reported from the group. 

 They differ, as do the barometric readings, from those that 

 have been published in the Blue Books of the Straits Settle- 

 ments, and which were based on the observations taken by 

 the Clunies-Ross instruments. Most of the discrepancy is 

 doubtless accounted for by the fact that the Pulu Tikus 

 readings are taken at 9 a.m. and 3 p.m., whilst the Clunies- Ross 

 observations are recorded at 6 a.m. only. The mean tempera- 

 ture is therefore actually several degrees higher than the 

 generally quoted 72°. Dr. Guppy's observations on the 

 temperature are also misleading ; he gives the mean tem- 

 perature as "about 78*50°"; but there is no doubt that in 

 the limits of his short stay he had no real basis for fixing 

 a mean temperature without consulting the Clunies-Ross 

 readings. 



The highest temperature recorded during the time that 

 my results cover is 94"3° on April 2, 1903, and the lowest is 

 61"0° on August 4, 1904, whilst the maximum daily variation 

 is 24-80°. 



The average maximum and minimum readings for the 

 different months are as follows : 





Max. 



MiN. 





Max. 



Min. 



Jan. 



. 91-1° 



72-2° 



Feb. 



. 90-4° 



72-3° 



March . 



. 90-0° 



72-9° 



April 



. 90-8° 



73-8° 



May 



. 89-.T 



73-0° 



June 



. 86-5° 



71-3° 



July 



. 86-7° 



70-0° 



Aug. 



. 86-r 



69-4° 



Sept. . 



. ,87-4° 



71-0° 



Oct. 



. 87-8° 



72-5° 



Nov. 



. 89-4° 



72-r 



Dec. 



. 89-6° 



72-3° 



Baeometric Readings. — The barometer shows steady 

 readings throughout the course of the year, the average 

 monthly variation being "220 ins. The average maximum 

 reading of all the months is 30*128 ins., which is considerably 

 higher than that recorded by the Clunies-Ross instrument. 



The averages of the maximum and minimum readings of 

 each month for four years are as follows : 



