596 
MR, J. NORMAN LOCKYER ON THE 
occasion in 1871, the 1474 ring was very bright, bat in 1878 I did not see it at all.” 
As the sun-spot period is one of about eleven years, it was to be expected that the 
conditions of 1871 would be repeated in 1882 and 1893, and during both these 
eclipses the 1474 ring was photographed with the prismatic cameras. The photo¬ 
graphic plates employed in 1875 and 1886 were not sensitive to the green, and, since 
no eye observations were made, we have no evidence as to the visibility of the 1474 
ring in those years. 
Although there can be no doubt as to a more or less regular change of intensity in 
the case of 1474 K, the evidence with regard to other radiations is less conclusive. 
Confining our attention in the first instance to the results obtained with slitless 
spectroscopes, we have the following data :— 
Date. 
Observers. 
Method. 
Spectrum. 
1871 
Respighi 
Visual 
C, 1474 K, F. 
Lockyer 
55 
„ „ F.G. 
1875 
Schuster 
Photographic 
Gr. 
1878 
Lockyer 
Visual and Photographic 
Continuous 
Ranyard 
Visual 
55 
Draper 
Photographic 
55 
1882 
Schuster 
55 
D s , 1474 K 
Lockyer 
Visual 
C, 1474 K 
1883 
Lawrence and Woods 
55 
1474 K (middle of totality) 
,, 
5 ? 55 
Photographic 
Continuous 
1886 
Darwin 
55 
,, (plate not sensitive to 
1474 K) 
1893 
Fowler 
55 
1474 K and 7 others 
Shackleton 
1474 K 
55 
Visual 
55 
Variation of Hydrogen. 
Hydrogen rings have only been recorded in the spectrum of the corona on three 
occasions—1871, 1875, and 1882; it is probable that the rings corresponding to 
hydrogen seen in 1883 w r ere produced b}^ the chromosphere and prominences, since 
they were not seen in the middle of totality. If the appearance of the hydrogen 
rings in the corona have the same connection with the sun-spot period as the 1474 K 
line, their presence in 1893 might have been expected. As they were not photo¬ 
graphed in this eclipse, the appearance of hydrogen rings might be regarded as 
subject to no law in relation to the sun-spot period, but, before coming to a decision 
on this point, it is worth while to consider very carefully the differences in the 
instruments employed in the various eclipses. To get at these facts Mr. Fowler has 
made a number of experiments to determine to what extent false rings may be 
produced in the visible and photographic spectrum when a slitless spectroscope is 
employed, similar to those produced photographically in the manner already 
