276 



KNOWLEDGE. 



[Decembek 1, 1900. 



OcfolxT, 1900), it occurred to me that tbese markings may 

 be due to tlie presence of dense swarms of meteoric bodies 

 near the sun. The markings of tbe coronas of 1871 and 

 1!H)0 seem to me to favour this view. The passage of a 

 dense swarm of meteorites between us and the corona 

 would, I think, show us a dark mark ; Imt the question 

 is, Would the markiua's be as dense as those described 

 by Mr. Wesley? ' H. W. 



Middlesbrougli, 



October'^2'lth, 1900. 



[H. W.'s suggestion is an obvious one ; but is ojien to 

 the objection that, in that case, we ought sometimes to 

 see dark lines due to meteor-swarms projected against 

 the disk of the sun ; which we do not. — E. Walter 

 Maundkb.] 



t > I 



RAINBOW PPIENOMENA. 



TO TUE EDITORS OF KNOWLEDGE. 



Sirs, — On the evening of September 16th, a remark- 

 ably vivid double rainbow was visible at Eastbourne 

 from 5.30 till after 6 o'clock, and its magnificent coloui'S 

 must have attracted the attention of many observers. 



A curious phenomena was consjjicuous on the inner or 

 violet edge of the primary bow. 



I have noticed on previous occasions that in the case 

 of brilliant rainbows the violet rays frequently reappear 

 as a distinct band within the primary bjw, an>4 separated 

 from it by a moderately wide unilluminated strip. 



But in the case under notice the phenomenon was 

 intensified to a remarkable degree, the violet band being 

 clearly triple, and the inner edge of the primary bow 

 exhibiting the following series of colours without any 

 aj^parcnt break — viz., green, blue, violet, gi-een, blue, 

 violet, green, blue, violet. Occasionally there appeared 

 to be traces of even a fourth (isolated) band of violet; 

 but upon this point I could not be absolutely certain. 



The general effect was curiously like the mouldings 

 on a stone archway, the inner edge of the bow presenting 

 the appearance of concentric ridges of green separated 

 by violet hollows. 



The three continuous bands, each consisting of green, 

 blue, and violet, were clearly seen by two others whom 

 I questioned on the subject. 



In the case of the simple repetition of the violet band, 

 I have often attributed the appearance to an ojitical 

 illusion, or even to some modification of the " ultra- 

 violet " rays, but the complicated redu]5lication of the 

 phenomenon which I witne:sed last Sunday has re- 

 awakened my interest in the subject, and I should be 

 very grateful if any of the numerous scientific readers of 

 Knowledge, to whom the subject may be of interest, 

 will offer some explanation of the phenomenon which I 

 have attempteii to describe. S. R. Stawell Brown. 



St. John's College, Oxford, 

 September 18, 1900. 



LUNAR RAINBOW. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — It seems pretty evident from the description 

 given by Mr. John Macinto.sh in your November issue, 

 that ttliat he saw was not a lunar raitihou' at all, but 

 what IS usually called a corona. The phenomenally long 

 duration (1^ hours), the smaller diameter, and the fact 

 that the lower portion was cut off by clouds, all point to 

 this conclusion; the diameter of a lunar (or solai') rain- 

 bow is, for the primary bow, always about 82°, the lower 

 part is always cut off by the earth (except in rare cases 



when the observer stands on the top of a mountain 

 peak), and anyone who has seen a bright lunar rainbow 

 endure for more than twenty minutes or so is fortunate 

 indeed. The following extract from my register may 

 interest your coiTespondent. 



" JanuaiT 31st, 1893, 9.1.5 p.m. Beautiful lunar 

 corona, the inner part of a brownish orange colour, and 

 then the coloui's of the spectrum in order from violet t,o 

 red, most clearly defined and pure." 



These coronse ai'e really diffraction rings, and accord- 

 ing to Kcemtz (Conrs de Meteorolofjie, page 424), may 

 have a diameter of from two to eight degrees, thus 

 agreeing roughly with your correspondent's estimate. 



Harewood Lodge, Charles L. Brook. 



Meltham, Huddersfield, 



November 6, 1900. 



The Royal Society's Medals have this year been 

 adjudicated by the president and council as follows: — ■ 

 The Copley Medal to Professor Marcelliu Berthelot, 

 FOR.MEM.R.s., for liis brilliant services to chemical 

 science ; the Rumford Medal to Professor Antoine 

 Henri Becquerel, for his discoveries in radiation pro- 

 ceeding from uranium ; a Royal medal to Major Percy 

 Alexander MacMahon, f.e.s., for the number and range 

 of his contributions to mathematical science; a Royal 

 Medal to Professor Alfred Newton, f.r.s., for his 

 eminent contribution to the science of ornithology and 

 the geographical distribution of animals; the Davy 

 Medal to Professor Guglielmo Koerner, for his brilliant 

 investigations on the position theory of the aromatic 

 compounds; and the Darwin Medal to Professor Ernst 

 Haeckel, for his long-continued and highly-important 

 woi'k in zoology, all of which has been inspired by the 

 spirit of Darwinism. 



■r^df^ 



ORNilHOLOGiCAlf 



^^:i 



% ' ■' 



NOTES . 



Conducted hy Harry F. Witheeby, f.z.s., m.b.o.u. 



Nesting-Boxes for Wild Birds. — Some details 

 respecting the nesting-boxes which I have been in the 

 habit of providing here for wild birds may be of interest. 

 The boxes are of two kinds, one for the use of small birds 

 the other for lai-ge birds. The smaller boxes are ten 

 ini'bes high and sis inches square, made of well-seasoned 

 oak. A hole, about one-and-a-half inches in diameter, is 

 bored in the front of the box for ingress and egress. The 

 roof, which is sloping, is provided with leatlier hinges, and 

 thus forms a lieavy lid, enabling the boxes to be cleaned 

 and the old nests taken out every year. A few small holes 

 are jnerced at the bottom of the box for draining purposes. 

 These boKes last for many years. We have a number about 

 that have been up from twenty-five to thirty years. They 



