July 2, 1900.] 



KNOWLEDGE. 



1-17 



given in India. We hoped that the two pairs of ex- 

 posures would therefore enable us to judge whether our 

 Indian exposures were the best possible, or whether 

 they were too long, or whether, on the other hand, 

 they might be safely increased. For the rest we had 

 no wisli to exactly repeat our Inflian experiment, a.s we 

 knew that tliis was being done by many competent 

 photographei-s with a variety of lenses and at several 

 widely separated stations. 



The result of our photographs show clearly that for 

 this eclipse at any rate the exposures whicli we have 

 given are too long; at least for the purpose of securing 

 the extensions. Totality lasting but for 62 seconds. 

 an exposure from the sixth second to the fifty-fourth 

 meant that the chromosphere was uncovered both at 

 the beginning and end of totality, and that the 

 brightest layers of the corona were practically exerting 

 their influence the whole time. The consequence was 

 that the sky illumination was far greater than at mid- 

 totality in the Indian eclipse, and probably on this 

 account the extensions cannot be traced to so great 

 a distance. We can feci no regret that this is 

 the case. It was our deliberate choice to extend 

 the exposure as much as the circumstances of the eclipse 

 allowed that we might complete our Indian experiences 

 as fully as possible. We trust, however, and have reason 

 to hope that at some of the other stations — possibly at 

 several — those photographers who were trying for the 

 extensions will prove to have secured them to a much 

 greater extent than we have on the present occasion. 

 Nevertheless, our photographs seem sufficient to show 

 that those rod-like rays stretch out from the synclinal 

 curves of the corona of 1900 as they did from that of 

 1898. 



The present ai'ticle is already sufficiently long, and we 



(.In trip Roof of the Hotel (te l:i Ki-gcucc, Algiei'i!. Hiss Leake at 

 lier Telesrope. 



Pltr,togi-aphfd ?<y Mi3s Edith Maundeb, 



must postpone to another month the consideration of 

 many important observations. Amongst these wc would 

 specially mention studies at the telescope of the details 

 of coronal structure. These were carried out most 

 successfully on the present occa.sion by Mr. Wesley, 

 Mr. Crommelin, Miss Leake, and no doubt many others, 



and form quite a new chapter in coronal observation. 

 The observations of the shadow bands were also of 

 unusual interest, and no doubt the next week or two 

 will bring us much further information as to the details 

 of coronal structure shown on the numerous short ex- 

 posure photographs. 



Wc reproduce a beautiful drawing made at our 



On tlie Hoof of the Hotel de Ja Regenee, Algiers. Mrs. Walter 

 Maunder and lier Two Cameras. 



Phtjtofjraphcd by Miss Edith Macnuer. 



Algiers station by Miss C. O. Stevens. It will be seen 

 that the form of the corona reproduced with astonishing 

 fidelity that seen in the eclijases of 1878 and 1889, 

 respectively two and one complete sunspot cycles earlier. 



THE GREAT INDIAN EARTHQUAKE OF 1897. 



By Charles Davison, sc.d., f.g.s. 

 To the inhabitants of India, the year 1897 will long 

 rank as a year of great calamities. A famine in Bengal 

 and the plague in Bombay were followed on June 12 

 by an earthquake in Assam, which, if it is not without 

 a rival, is certainly one of the most disastrous and widely 

 felt of which we possess any record. The investigation 

 of the earthquake was at once undertaken by the mem- 

 bers of the Geological Survey of India. The four 

 officers who were at the headquarters in Calcutta were 

 despatched to collect information from the area in 

 which the chief damage was done, letters and circulars 

 were distributed as widely as possible, a large number of 

 volunteer observers were induced to co-operate by keep- 

 ing records of the after-shocks, and, later on, during the 

 cold weather of 1897-1898, Mr. R. D. Oldham, one of 

 the superintendents of the Survey, made a tour through 

 the epicentral district. To Mr. Oldham has also fallen 

 the much more severe task of collating the observations, 

 of determining the value to be assigned to each, and of 

 discovering the conclusions to which they lead. The 

 latest volume of the Memoirs of the Geological Survey 

 of India, a book of more than 400 pages, contains the 

 fruit of his work ; the interest and importance of which 

 will be seen from the summary given in the following 

 pages. 



DiSTUHBED Area, etc. 

 The area over which the earthquake was perceptible 



