August 3, 1900.] 



SCIENCE. 



175 



work were much hurried, but we had grat- 

 ings of which the curves were carefully com- 

 puted for the focal length of the quartz 

 lenses. At Griffin we obtained a reversing 

 layer of eight seconds. Mr. Jewell has 

 brought some copies of the only successful 

 plates at Pinehurst, showing several new 

 coronal lines, one coinciding M'ith the 1474 

 lines, and there were three other new lines. 

 Dr. Dorsey of the Johns Hopkins Univer- 

 sity also took photographs, and Dr. Wood 

 of the University of Wisconsin undertook 

 to study the shadow bands which precede 

 and follow the eclipse. He is not hei'e, but 

 he thinks he has reached a satisfactory con- 

 clusion with regard to the cause of the 

 shadow bands. While our results in spec- 

 troscopic work were disappointing, in view 

 of the large outlay, they seem to vindicate 

 the value of that method. We think we 

 shall be able to obtain a plate which will 

 bend to the required curvature, and thus 

 be able to photograph the reversing layer. 

 L. E. Jewell. We obtained a differ- 

 ent wave length for the bright and for 

 the corresponding dark lines ; and I think 

 that difference in wave length is caused by 

 the fact that the dark lines were produced 

 very close to the moon's edge, by the re- 

 maining portion of the crescent, not cov- 

 ered by the moon, while the bright lines 

 were produced further out. On one of the 

 photographs taken at Pinehurst there is a 

 very distinct difference of the H and K 

 lines, between the bright and dark portions 

 of the spectrum. The bright line is dis- 

 placed with reference to the dark line in the 

 direction outside, or further away, from the 

 sun itself, just as it should be if that were 

 the true explanation. In determining the 

 method we should follow in the use of 

 these plates we were largely influenced by 

 the results of Evershed in India in 1898, 

 showing that the chromosphere and revers- 

 ing layer were much brighter in the upper 

 part, showing other interesting phenomena. 



Another interesting thing was the presence 

 of the rare element scandium. It was 

 thought best to use his grating for the pur- 

 pose of our work, and I made comparisons 

 showing that he used a dispersion about 

 three times that of a single prism ; and we 

 concluded that we could obtain at least as 

 much light from our grating as from a 

 prism. Our results at Pinehurst were 

 thought of extreme importance. With an 

 exposure of only one second we obtained 

 results showing that if we had been able to 

 bend the plate to the required focal length, 

 it would have given us a spectrum from 

 wave length 30 to 60, giving us 1300 lines ; 

 the effect being very sharp lines in the 

 neighborhood of the if and ^calcium lines, 

 and pictures of the chromosphere proper 

 and the reversing layer showing 50 to 75 

 prominences. The difference between the 

 calcium and the hydrogen lines was shown 

 very prominently indeed. A plate out of 

 focus showed the yellow sodium line, and 

 the coronal lines at 1474 which were seen 

 much stronger on the opposite side of the 

 sun from that where the ordinary bright 

 lines are seen. This green line was much 

 brighter than on the western side of the sun. 

 There is no line which seems to be evenly 

 distributed on the two sides of the sun. The 

 green line seems to be gathered into a very 

 short arc on the western limb. On another 

 plate taken 25 seconds later, the exposure 

 was 5 or 6 seconds, and on that these 

 coronal lines are shown all the way round. 

 There are four lines not obtained before, 

 the substance producing them seeming to 

 be about the same as that giving the green 

 lines. They show the strongest at some 

 distance from the sun's surface, say three 

 to five thousand miles above the solar sur- 

 face, although they are visible close to the 

 solar surface. Another interesting thing 

 was the beautiful way in which the carbon 

 band showed with an exposure of one 

 second. It was very strong a hundred 



