78 Address. [Feb. 



Trigotiomeirical Branch. — During the year the laying out of a princi- 

 pal series of triangulation in Upper Burma on the meridian of 96° 30' was 

 commenced, but no final work on the series was obtained. In addition 

 to this work, the same party carried on operations for fixing beacons 

 along the Burma coast for the Marine Department, points suitable by 

 their conspicuous appearance being selected and their position deter- 

 mined. 



Tidal and Levelling operations. — The recording of the tidal curves 

 by means of self-registering tide-guages, their reduction and the publica- 

 tion of predicted heights have been continued, and tidal observations 

 have been carried on during the year at various stations round the coast 

 of India and Burma and at Aden and Port Blair. 



In connection with the Tidal Observations, it is interesting to observe 

 that in a paper by Dr. G. H. Darwin, F.R.S., in the Proceedings of the 

 Boyal Society, it is pointed out that variation in the sun's temperature 

 may possibly be a cause of variation in the mean-sea-level, and, if so, 

 a periodicity with a period of 10 or 11 years may be expected. Obser- 

 vations at Karachi, show that there was a minimum of sea-level in 1872, 

 and again in 1882, but these observations are clearly insufiicient to do 

 more than raise the question. 



Dr. Darwin speaks in the highest terms of the Indian observations, 

 and it is to be hoped that as time goes on it will be possible to prove 

 the correctness of the theory he now puts forward, by the observations 

 at some of the permanent stations. 



A comparison of tide-registers at Karachi with those at Sydney, 

 N. S. Wales, shows that the variation of mean-sea-level occurs simul- 

 taneously at both these ports, but is more noticeable at the latter one. 

 Endeavours are being made to establish a tidal observatory on the 

 Island of Minicoy, as being especially valuable for the study of the 

 oceanic tides, undisturbed by coast influences. 



Spirit-levelling operations were carried on during the year from 

 the Bangalore base to Mangalore, and from Bidar to Hyderabad 

 (Deccan). 



Latitude operations. — It found was necessary, owing to paucity of 

 officers, to abandon temporai-ily the electro-telegraphic longitude opera- 

 tions, which require two trained officers to superintend them, in favour 

 of the latitude operations for which only one is necessary. Seven stations 

 were observed, situated between the latitudes of 19° 49', and 16° 26', 

 and near the meridian of 80°. It is worthy of note that at six out of 

 the seven stations the same excess of geodetic over astronomical latitude 

 still appears as in the previous year, averaging nearly 6". In other 

 words a deflection of the plumb-line to the north is in operation through- 



