72 



H. F. Blanford — On Hiijh Atmosplieric Pressure 



[No. 1, 



was more intense than at any other station j^et examined either in Australia 

 or India. At this station, the pressure rose above the average in May 1876 

 (as at the islands in the Bay of Bengal) and, with the exception of 4 montlis, 

 remained in excess until J une 1878 ; the average excess of the whole period 

 being not less than -0681" or of an inch of the barometer. At Mel- 

 bourne, during the same period, it averaged -0387" and was less prolonged. 

 For Sydney, I have registers only up to September 1878, and these shew an 

 excess much below that of Melbourne. It would seem, therefore, that in 

 Australia as in Asia the excessive pressure diminished towards the east 

 coast of the continent. 



As a link between the data of the Indian and Australian regions, I have 

 the registers of Singapore and Batavia ; for the latter of which I am 

 indebted to the kindness of Dr. Bergsma. At Singapore, the same barome- 

 ter has not been in use throughout. The barometer registered in 1869 and 

 1870 having been injured, was replaced by another in 1871 which had never 

 been compared directly or indirectly with the former; and the relative values 

 of the registers in the two former and subsequent years are, therefore, more 

 or less open to doubt. The position of the instrument also has been 

 changed once or twice ; but, in comparing the registers of past years, I 

 have applied an appropriate correction for the changes of level. The 

 registers extend from May 1869 to the present time. According to these, 

 during the four and a half years, from May 1869 to October 1873, and 

 certainly from July 1871, in only two months, was the mean pressure of 

 any month slightly above the general average of the month, as deduced 

 from the whole series of years; whereas, from November 1873 to February 

 1875 (16 months in all), ten months ranged above it, and six only below it ; 

 and from March 1875 to June 1878, every month shews an excess, except- 

 ing April 1876 (which was the same as the average) and November 1876 

 and December 1877, which were slightly below it. Hence, it appears that 

 the excessive pressure began earlier and was more prolonged at Singapore 

 than at any other station yet examined ; but it was less than half as intense 

 as at Adelaide ; the average of the 26 months. May 1876 to June 1878, 

 being only 0293". 



The register of Batavia affords evidence very similar to that of Singa- 

 pore. Here also from November 1869 to August 1873, a period of 3 years 

 and 10 months, in only four months did the pressure range slightly above 

 the average ; from the latter date to April 1876, in ten months it exceeded 

 the average ; and from May 1876 to August 1878, it was above the average 

 in every month except three. The average excess of this period was -0256." 

 Thus, at these two sub-equatorial stations, there is evidence of a gradual rise 

 of atmospheric pressure since 1870 ; and the Batavian register recorded 

 under the careful superintendence of Dr. Bergsma is of the highest validity. 



In Ceylon and Southern India, the excessive pressure was of shorter 



