250 



Major A. W. Baird. Report on the 



[Jan. 31, 



viz., the uniform scale of 1 inch = 3 feet for height and=6 hours for 

 time. The original diagrams are too bulky to be reproduced to full 

 scale for publication ; but Major Baird presents in his report all the 

 details which they furnish by giving the numerical elements of the 

 time and height of every appreciable supertidal wave, remarking, 

 with characteristic modesty, that thus the whole of the facts will be 

 available for the further treatment of the subject by more competent 

 hands. 



The principal facts set forth by Major Baird are the following :— 

 1st. The primary effect of the great eruption at Krakatoa was a 



marked fall in the sea level — or in other words, the .formation of a 



negative supertidal wave — at each of his stations. 



2ndly. This negative wave was succeeded by a great positive wave 



at an interval ranging from seventy-five minutes at Negapatam, the 



station nearest Krakatoa, to twenty-four minutes at Aden, the most 



distant station. 



3rd. Supertidal wavelets of greater or less magnitude were regis- 

 tered at the whole of the Indian stations some hours, more or less, 

 before the effects of the great eruption ; they are evidences of ante- 

 cedent minor eruptions, the occurrence of which they would establish 

 even in the absence of all other information on the subject. The 

 intervals between these warnings and the great eruption which they 

 heralded range from about three hours at Aden, the most distant 

 station, to eighteen hours at Negapatam, the nearest station. This 

 shows that the explosions were at first comparatively faint and feeble, 

 being felt only at the nearest stations, but afterwards they increased 

 in intensity, becoming sensible even at the most distant station 

 three hours before the effects of the great eruption. 



4th. Great supertidal waves of amplitudes ranging from a maxi- 

 mum of 22 inches at Negapatam to a maximum of 9 inches at Aden, 

 were registered at all the stations which were in a position to receive 

 the full force of the eruptions at Krakatoa, unobstructed by the con- 

 figuration of the foreshore. Other waves of less magnitude, ranging 

 down to half the maxima values, occurred at these stations at intervals 

 of one to two hours for about twelve hours after the first great wave. 



5th. The secoudary great waves were succeeded by wavelets 

 gradually diminishing in size, but continuing for some time ; they 

 are traceable on the diagrams for the 29th and 30th August, the 

 second and third days after the great eruption ; they cease first at 

 Port Blair about 8 p.m. of the 29th, at Negapatam at 4 a.m. of the 

 30th, and, lastly, at Aden at 5 p.m. of the 30th. 



6th. Loud reports resembling the firing of distant guns were heard 

 at Port Blair and on the Nicobar Islands on the 26th and 27th 

 August, and being supposed to be signals from a vessel in distress a 

 steamer was sent out in search of the vessel ; similar reports were 



