June 25, 1908] 



NA TURE 



175 



as its position-angle ; its form has, however, considerably 

 changed in the interval of time between the exposures. 

 Mr. Fox kindly forwarded me a photograph of this 

 prominence, which is here reproduced (Fig. 2), and he 

 oriented it in the corner on rather a small scale. This 

 orientation is reproduced by me on a larger scale in white 



Fig. 2. — The large prominence in the south-west qu.i 1 graphed in 



calcium light by Mr. Philip Vox on July 17, 1907, at ^ii. 5um. G.M.T., 

 at the Yerkes Observatory, U.S.A. 



on the photograph. It will be noticed that the upper por- 

 tion of the prominence is directed from the south towards 

 the west, but in the Kensington photograph (Fig. i), and 

 also in Prof. Hale's (Fig. 3), the material is directed from 

 the west towards the south. The question arises, is Mr. 

 Fox's orientation right (his position-angle is correct), or 

 has the material altered its positic»n between the times 



Fig. 3. — The Sun's disc and prominences on the limb, photographed in 

 calcium light by Prof. Hale on July 17, 1907, at ih. 46m, p.m. G.M.T., 

 at Mount Wilson, U.S.A. 



the photographs were taken ? I am rather inclined to 

 question the orientation. 



Directing attention now to the triple arch prominence 

 about position-angle 137°, which was shown in the first 

 of the Kensington negatives (Fig. i), I pointed out that 

 in the second photograph, taken thirty-six minutes later, 



NO. 2017, VOL. 78] 



only remnants of the system remained. So rapidly did the 

 whole of this disturbed region wane in intensity that it is 

 not astonishing to hear that two hours later Mr. Fox re- 

 ported that no prominence of unusual form was there. 



The recent communication to this Journal (vol. Ixxviii., 

 p. 151, June 18) by Mr. A. A. Buss is of great interest 

 to me, because it made me acquainted with a photograph, 

 secured by Prof. Hale, of the same prominence taken half 

 an hour previous to the first Kensington picture. Through 

 the courtesy of Mr. Newbegin, jun., I received a copy of 

 tills very interesting photograph, and one is now able to 

 follow more accurately the sequence of events in the dis- 

 turbed area. I hope Prof. Hale will forgive me for re- 

 producing his photograph here (Fig. 3), but it is only by 

 showing the two photographs together that a satisfactory 

 comparison can be made. I have ventured to insert the 

 orientation on Prof. Hale's photograph in order to render 

 the identification of the proninences more easy. 



The most striking difference between the two photo- 

 graphs is, apart from their form, the great intensity of 

 the large prominence in the south-east quadrant in Prof. 

 Hale's picture (2h. 46m. p.m. G.M.T.) and its comparative 

 faintness in that obtained at Kensington (3h. 14m. p.m. 

 G.M.T.) ; other prominences are of about the same intensity 

 in each. This diminution of brightness indicates how 

 rapidly the prominence must have waned during the 

 twenty-eight minutes' interval betw^een the exposures. 

 The second photograph taken at Kensington (3h. 50m. 

 p.m. G.M.T.) showed that this rapid waning had con- 

 tinued. 



.\ccording to Mr. Buss's visual observations, made 

 between ih. 30m. and 2h. 20m. p.m. G.M.T., i.e. before 

 Prof. Hale's photograph w^as taken, the disturbance as a 

 whole commenced at about position-angle 112°, where an 

 eruptive prominence was situated. The material from this 

 prominence was ejected towards the south pole, dissolving, 

 as he describes, " from a stout, dense and bright stem 

 into a number of bright, more or less parallel layers of 

 striaa." This appearance is shown in Prof. Hale's photo- 

 graph, but when the Kensington photograph was taken it 

 had assumed the form of concentric arches. These addi- 

 tional facts make me endorse Mr. Buss's opinion, that is, 

 that it is unnecessary to assume that the material form- 

 ing the arch system originated from a disturbance below 

 it, or, as I stated in my paper, that " their concentric 

 nature seems to suggest that they were produced at one 

 point of initial disturbance and then moved radially out- 

 wards." 



It may be added that these new facts in no way in- 

 validate the conclusion drawn in my paper, which was 

 that envelopes, similar in form to those photographed 

 during eclipses, had been recorded in calcium light, thus 

 strengthening the view that they were composed of 

 prominence and not coronal matter. 



WlLLI.IM J. S. LOCKYER. 



Mendelism : a Personal Explanation. 



I SHOULD be glad if room could be found for this small 

 matter of personal explanation. I fear I may have misled 

 one or two of your readers on a minor point. Those of 

 ihem who are interested in the interpretation of hereditary 

 phenomena may remember that in the number of this 

 Journal for .September 12, 1907, Mr. Punnett took a 

 reviewer to task for saying that " No one has repeated 

 Mendel's experiments with the deliberate intention of test- 

 ing the Mendelian interpretation " (of the phenomena of 

 inheritance). In my reply I was not content with defend- 

 ing my original position by justifying that statement; but 

 I must needs carry the war into the enemy's country by 

 taking Mr. Punnett to task for not including de Vries's 

 papers in his list of memoirs dealing with repetitions of 

 Mendel's actual experiments, in order to show how familiar 

 I was with the literature of the subject. 



I wish to say that if I had been as familiar with the 

 literature of the subject as Mr. Punnett was, I should 

 not have taken the offensive. Mr. Punnett was quite right 

 in not including a reference to de Vries's papers, because 

 Prof, de Vries, though he has watched the results of 

 crossing in other plants, has not worked with peas. I 

 was misled by the commonly repeated statement that 



