114 THE INDIAN ECLIPSE, 1898. 



,THE CORONA AS SEEN ON PHOTOGRAPHS OF LONG EXPOSURE.* 



IT will be seen from the table on p. Ill that two photographs 

 (Nos. 29 and 30) taken during the eclipse had a much longer 

 equivalent exposure given to them more than 2 minutes with 

 yyi5 than has ever been given before to a coronal negative 

 with plates of corresponding rapidity. These photographs were 

 taken, as already stated, on Sandell Triple-Coated Plates, and 

 were developed according to the formula which follows : 



grs. 

 Hydroquinone . 20 



Metol 

 Sulphite of Soda . 

 Bromide of Potassium 

 Citric Acid . 

 Carbonate of Soda 

 Caustic Soda . 

 Water to 5 oz. 



2 

 130 

 6 

 3 



90 

 6 



Two other plates, both taken on Ilford Extra Rapid plates, 

 are interesting to compare with these. These are Mr. Cousens' 

 photograph of 4 seconds exposure (No. 20), and Mrs. Maunder's, 

 No. 27 (equivalent exposure for //1 5, 31 seconds). 



The first two photographs give a presentment of the corona 

 such as has not been yielded by any previous ones. They fail 

 entirely to give anything of the wonderful detail of the inner 

 corona. The scale on which they are taken is too small 

 for that, and their exposure too prolonged. But they give a 

 better idea of the corona as seen by the naked eye than perhaps 

 any other whatsoever. And in so doing they afford a strong 

 and unanticipated confirmation of the truthfulness of a large 

 number of eclipse drawings. 



Sketches of the corona have fallen not a little into disrepute 

 of recent years ; partly because of the serious difficulties that 

 interfere with the production of faithful coronal drawings, 

 but principally because the forms ordinarily presented in such 

 drawings have not received support from photographs. The 

 corona as registered by eye and hand, and the corona as 

 registered by the sensitive plate, seemed to be two different 

 structures. 



The present photographs give, we think, the explanation of 

 this seeming discrepancy, which resembles in its nature that 

 between the two artists, Mr. and Miss Hall, at the 1874 eclipse, 

 alluded to on p. 88. For if we compare the corona as shown 

 on these photographs with the drawings made by the sketchers 

 at Buxar, we can have no doubt as to the general accuracy 

 of the latter. It is clear that if we had had no photographs 



* By Mr. and Mrs. Walter Maunder. 



