376 



KNOWLEDGE & SCIENTIFIC NEWS. 



[March, 1906. 



To the Editors of " Knowledge &• Scientific News." 

 Sirs, -^ftcr roadint;- Professor Grorsje Ilenslow's letter, in 

 vvhieh he tal<es me to task for certain omissions in my 

 paper, " The Evolution of the Flower," I am led to think 

 that he can scarcely realise the vastness of this subject. 

 Why, the additional examples which he thinks should have 

 been included misjht he multiplied by one hundred fold ! 

 Moreover, several of the points to which he alludes were 

 hinted at in my article, but space would not permit of their 

 enlarg^ement. 



If Professor Henslow will refer to my text he will notice 

 that after remarkintr that the sepals and petals of the Tulip 

 flower are identical, I have placed the savinij- clause " as 

 far as the ordinarv observer can say." I am g'lad that 



Hulton ,( Sons. 



attention has been called to the error which has crept in by 

 an oversight regarding- the sepals and petals of Campanu- 

 late flowers; of course, the " bell " is only formed of the 

 petals, the calyx being quite distinct. The same point is 

 illustrated in the tube-sh.aped flowers of the Gloxinia, an 

 interesting " cup and s.aucer " variety of which has been 

 recently introduced. By the courtesy of Messrs. Sutton and 

 Sons 1 am able to send you a photograph of this remark- 

 able form. 



I should like to Ihank Professor Hen-!ow for his elabora- 

 tions of many points concerning which 1 had to deal all too 

 briefly. 



^'ours etc., 



S. Leonard Bastin. 



Febniary 13, 1006. 



igoi. 



ig02, 



The Green Flash at Sunset. 



To the Editors of " KNOwi.FncE & Scientific News." 



Dear Sirs, — Having seen a letter in your last issue (Feb- 

 ruary. igo6) concernins the so-called green flash at sunset. 

 I think it may lie of interest to the writer of the letter and 

 some other readers to hear of some of my observations on the 

 phenomenon. Therefore, I am sending some extracts from my 

 notebooks. The last one is especially interesting, as the 

 position of observation and weather were very favourable, 

 and also as I was expecting the occurrence. From the descrip- 

 tions in my notes, I feel quite sure that the phenomenon is 

 not an optical illu.sion, but an objective reality caused by the 

 refraction of the air which acts like a prism upon the last 

 rays of the setting sun, giving rise to a series of colours as 

 observed ranging from the red to the extreme violet end of 

 the spectrum. 



I have noticed the same red flashes in Venus, and also 

 Jupiter and several other stars when I have seen them setting 

 behind the mountains in Egypt, near Assouan. 



I have seen the green, or rather many-coloured, flash also 

 behind the mountains at sunset in Egypt ; but it is neither 

 so clear nor of such long duration when seen over land as 

 over sea. 



Here are the extracts: — 



igo2, March 2g. — Sunset well seen, vivid blue line (at sea, 

 near Alexandria). 

 Nov. 17. — Sunset, last arc disappeared 5 hrs. 2-2 niin. 

 ship's time off Corfu or Ionian Islands (not in 

 sight). (At sea.) 

 Feb. 2. — Venus set over mountains about 6.40 p.m. 

 (Cairo time) at Assouan. The red colouring on 

 the crescent in flashes was conspicuous, 

 igoj. Aug. 31. — At Scourie, Sutherland, N.B.,and Lat.58"2i N. 

 Long. 5"9' VV. 

 7-25'5 p.m- — At the last contact of the sun's upper limb, 

 the " blue line " appeared. \\"hen the sun's 

 /(i.'.'iT limb was about 15' above horizon, it 

 appeared intense red. 



The blue line began to show evidence of its coming about 

 30 seconds before the sun disappeared. At first the whole of 

 the visible portion of the disc of the sun turned intense fiery 

 red. Then when a little more than half the disc had disap- 

 peared it changed to j-ellow. Then when only about i-6th was 

 left, there were green flashes round the edge of the disc lasting 

 perhaps a second each, and passing round a short arc begin- 

 ning always at the horizon. Then similar blue flashes 

 appeared. Then when the sun is almost down the whole 

 visible part became greenish with violet flashes. Then the 

 part of the disc visible becomes a line with deep violet at each 

 end, blue next to the violet, and green in the middle parts of 

 the line. Then the violet takes the place of the blue, and 

 blue is in the middle, while deeper, almost ultra violet, colours 

 the ends of the line. Then there is a lingering, rippling flash 

 of deep violet, and the sun is gone. 



The flash (as a whole) was much clearer and lasted longer 

 than I have ever seen it before. The telescope used was 

 about 15 in aperture, with magnifying power 45. 



The sea horizon was perfect, and the altitude above sea- 

 level about 55 feet ; weather calm, light S.W. wind ; filmy 

 clouds in part of the sk}', part clear with cloud wisps like 

 nebula. Temp, about 52° F. 



This description I copy from my notes written on the spot 

 the same evening. 



I used no dark glass on the telescope. 

 I am. Sir, 



Vours very truly, 



James H. Worthington. 



25, Museum Road, Oxford. 



To the Editors of " Knowledgf A: SriENTiFic News." 



Sirs, — Referring to .-Vdmiral Maclear's letter on this very 



interesting and beautiful phenomenon, I hav'e been much at 



sea, and have always taken great interest in, and watched at 



every opportunity tor a sight of it. I have heard all sorts of 



