206 TIDAL AND LEVELLING OBSERVATIONS. 



of spirit-levels between the sea at Karachi, on the Indian ocean, 

 arid False Point, in the Bay of Bengal. This line runs from 

 Karachi up the Indus to Mithankot and onwards via, Firozpur, 

 Agra, Allahabad, Monghyr, and Calcutta to False Point, a distance 

 of about 2,300 miles, or as far as from London, straight across the 

 Channel, Germany, and Russia to Astrakhan. It is probably the 

 longest line ever run between two seas, and the error in levelling, so 

 far as is known, does not exceed 1'7 foot, or under nine inches per 

 thousand miles ; in its absence accurate sea-level as a datum was 

 unknown throughout the vast length it traverses. 



During 1883-84 three new stations were opened at Marmagao, 

 on the Malabar coast, and at Galle and Colombo in Ceylon. The 

 predictions for 18B3 were found to be good ; they may be sum- 

 marised as follows : — 



Percentage of predictions within 15 minutes of actuals. 



High Water. Low Water. 



Open coast stations - 72 per cent. - - 70 per cent. 

 Riverain - - 70 ,, - - 66 ,, 



Percentage of predictions within 8 inches in height of actuals. 

 High Water. Low Water. 



Open coast stations - 92 per cent. - - 96 per cent. 

 Riverain - 66 ,, - - 64 ., 



A connecting link was also interpolated during the following 

 season between Sironj and a station 32 miles north of Maumad, on 

 the Bombay and Agra road, completing a line of levels between 

 two sea-coast stations very little inferior in length to the chain just 

 mentioned ; the closing error was only -624 of a foot, or less than 

 four inches per thousand miles. 



In 1884-85 the observations of Beypur and Yizagapatam were 

 closed, after a full course of work extending over five years, and 

 their equipment was removed for the erection of two new observa- 

 tories at Cochin and Coconada. At False Point the observatory was 

 unfortunately swept away by the cyclone which committed such 

 devastation on the coast of Orissa, on the 22nd September 1885. 

 Captain Douglas, the port officer there, lost his life, as well as the 

 tidal observatory clerk. Chittagong and Bhaunagar were started in 



