130 THE INDIAN ECLIPSE, I 



TWILIGHT ILLUMINATION. 



IT occurred to two members of the Association, quite inde- 

 pendently and- in ignorance of what the other was doing, to 

 attempt to estimate the time at w r hich the general illumination 

 after sundown corresponded to that during mid-totality. Mr. 

 T. W. Backhouse, at Benares, on the day following the eclipse 

 records: "Watch-time O h - 40 m> . I judge the light during 

 totality to have been about equal to that now existing." A 

 friend who was with him, Mr. Irwin Sharp, on the following 

 evening, January 24th, at watch -time O h - 36 m thought "the 

 darkness greater now than during totality." Mr. Backhouse 

 reported at the same moment that he thought it was not so 

 dark. 



. Mr. Walter Maunder, at Nagpur, on January 26th, was 

 very much struck with the resemblance in the general effect 

 of the coming on of twilight to the approach of totality, 

 both as to sky illumination, general light and appearance of 

 surrounding objects. He noted at 6 h 1 5 m ' Madras time that it 

 was nearly the same effect as at mid-totality, but on the whole 

 distinctly brighter ; at 6 h - 20 m - he noted again that it was dis- 

 tinctly darker than during mid-eclipse. Taking the mean of 

 these two times gives the light equal to mid-totality at 30 J 

 minutes after sunset. Mr. Backhouse's observation of January 

 23rd gives it at 34 J minutes, the watch being 3J minutes fast 

 of Greenwich mean time. Mr. Backhouse and Mr. Sharp's 

 observation on January 24th, when combined, gives 30 J minutes. 

 Mr. Maunder's on January 26th gives 30^ minutes. The 

 agreement between the observations made, so entirely without 

 preparation or knowledge of what to expect, seems to imply 

 that it was one which can be made with much more precision 

 than might have been expected, and it will be well worth 

 while to repeat it on all future occasions of an eclipse in 

 the tropics. 



We may conclude that the general illumination from 30 to 35 

 minutes after geometrical sunset reproduced very precisely the 

 illumination at mid-eclipse. 



VISUAL IMPRESSIONS AS TO THE BRIGHTNESS OF THE CORONA. 



MR. Walter Maunder's note on this point is as follows : 



" In Norway, 1896, there was a slight difficulty in reading 

 the actual divisions of the little seconds dial of the chrono- 

 meter, though the seconds hand itself could be readily followed. 

 In Carriacou in 1886. the writing I had placed on my camera 

 a large dark distinct text hand could just be read. Now 



