62 Genl. J. T. ^N aWev—Earili^ualce ofSlsi Dec, 1881. [Maech, 



Survey at a station on the Island of Kisseraing, below Tenasserim, on tlie 

 east coast of the Bay, as a part of the operations which are described in 

 paragraph 34 of the Report of the operations of the Survey of India 

 for 1881-82. He writes that he " saw the earthquake before feeling 

 it," as he was at the moment observing a signal — distant some 15 

 miles — which appeared to rise and fall in the field of the telescope ; 

 on looking at the levels of his instrument, he found that they were 

 violently agitated. He immediately recorded the time at which the pheno- 

 menon occurred. Subsequently he ascertained that the earthquake had 

 been felt at almost the same moment, at Madras and False Point, on the 

 opposite coast. Thus then Major Rogers, assuming the great earth-wave 

 to have travelled with equal velocity in all directions from the origin or 

 centre of impulse, considers that the origin must have been situated at 

 some point in the Bay nearly equi-distant from Madras, False Point, and 

 Kisseraing, — not in the centre of the triangle joining the three places, but 

 more to the south, towards the line joining Port Blair and Negapatam, 

 which was probably the line of greatest disturbance, as at those places the 

 sea-waves were greatest. 



It is remarkable that there should be no indication of any sea-wave 

 at either of the tidal stations at Rangoon, Elephant Point, Moulmein or 

 Amherst. This may be due to the circumstance that the belt of islands 

 and shoals which extends from Cape Negrais down to the Island of Sumatra 

 forms a barrier to waves issuing from an origin near the centre of the Bay ; 

 the sea-waves were propelled with great violence against these islands on 

 all sides and over the surrounding shallows, but they seem to have died 

 away rapidly in the deep sea beyond. Moreover, the great earth-wave must 

 have operated with far greater force towards the west than towards the 

 east of the centre of impulse ; for violent shocks were felt all along the 

 west coast of the Baj^, and to a considerable distance inland, whereas on 

 the coast the shocks were very slight and barely perceptible. 



The accompanying Chart of the Bay of Bengal sho%s the positions of 

 all the tidal stations on both coasts, the trigonometrical station at Kisse- 

 raing, and Major Rogers' assumed centre of impulse. It also gives the 

 values of all the soundings in the Bay which are believed to have yet been 

 taken. Major Rogers' report is also annexed i7t extenso, and will be 

 found to contain much additional matter of interest, including estimates 

 of the respective velocities of the earth- wave and the primary sea- waves. 

 It is believed that so full an account and such precise details of the pheno- 

 mena of an earthquake have rarely been acquired hitherto. That they 

 have been obtained in the present instance is mainly due to the existence 

 of the many tidal stations which have been established on Indian coasts. 



