February, 1913. 



KNOWLEDGE. 



51 



White," " Black-veined White," and so on, a 

 tendency which is also, no doubt, responsible for the 

 frequent coincidence of markings on both sides of 

 the wings, as in the " Brimstone," " Clouded 

 Yellow," " Apollo," and so on. 



Such tendencies are obviously opposing ones ; and 

 one is often lost in admiration at the wonderful 

 methods by which Nature has reconciled them, 

 often producing the most perfect protection and at 

 the same time the greatest beauty. It is conceivable 

 also that in such a case as that of Danais cJirysippus 

 the upper side of the wings may have warning 

 colours while the under side, where the yellow of the 

 hind wings is repeated at the tip of the fore wings, 

 as in Anosia menippe, may be protective, to 

 guard against inexperienced enemies who do not 

 know that they are unpalatable for eating, and so 

 would kill or injure them in mistake, just as cats kill 

 innumerable shrewswhich afterwards they will not eat. 



This detail in colouring shows with what minute- 

 ness Nature carries out the plan of protective 

 colouration and resemblance, and how small a piece 

 of detail gives some advantage in the struggle for 

 escape ; for otherwise this little bit of colouring 

 would not have continued. In further illustration 

 of the minuteness observe the delicate imitation of 

 a tear in the wing of Kallima (see Figure 53). Only 



with a magnifying glass can one see that the tear is 

 not real, and that the wing is perfect. The effect is 

 produced by alternate black and white markings. 



The success of the protective colouring is frequently 

 forced on the attention of the butterfly hunter, who 

 finds that the insect he has been pursuing has dis- 

 appeared from his view though he knows and sees, 

 just too late, that it has been all the while within 

 a very small plot of ground. 



There is also another point of view which I have 

 not seen brought forward, as to the success of this 

 sort of protection. It is this : — That an animal has 

 no time to waste in examining objects which at closer 

 quarters might (though a little suspicious) turn out 

 to be really twigs or leaves ; and thus a very imper- 

 fect resemblance (to our eyes who have plenty of 

 leisure for the examination) would often be sufficient, 

 and would be preserved till in process of time a 

 more and more perfect resemblance was evolved. If 

 one watches a bird supplying its ravenous nestlings 

 one can easily see that it has to do the work at full 

 speed. 



If we sometimes thus placed ourselves in the 

 position of animals, and by imagination " identified 

 our minds " (in E. A. Poe's phrase) with theirs for 

 awhile, we should very often comprehend Nature 

 better and discover more of her secrets. 



CORRESPONDENCE. 



A PHYSICAL PHENOMENON. 

 To the Editors of " Knowledge." 



Sirs, — The enclosed Note on a physical phenomenon which 

 was observed at Maymyo towards the end of last May will, it 

 is believed, prove of special interest to your readers. The 

 author of the note is Mr. H. M. S. Mathews, C.S.I., Com- 

 missioner of Settlements and Land Records, Burma, and is 

 the outcome of his personal experience of the occurrence. 



Maymyo is a hill station, the summer headquarters of the 

 Government of Burma. Its geographical position is 22° l' N. 

 and L 96° 29' E. ; and its height above mean sea level is three- 

 thousand seven hundred and eighty feet. The Moon was full 

 on 31st May at 5 h 59"" 36 s a.m., when its R.A. was 17° and 

 Dec. 27° S. ; so that the phenomenon would have been visible 

 when the Moon was in the E.S.E., and about 20° to 40 D in 

 altitude. 



The special points about the particular phenomenon are : 

 first, that the luminous area behind the shadow of the head 

 was accompanied by an entirely distinct circle of light some 

 distance away from the luminous area, the feet standing on 

 the circumference of this circle; second, that the phenomenon 

 was seen by the light of the Moon, not the Sun. 



The phenomenon is believed to be what is known as Anthelia 

 or " Glories," the following description of which is taken 

 from an Encyclopedia, viz. : " Anthelia are luminous rings 

 seen by an observer on a cloud or fog which lies opposite to 

 the Sun. They are only seen when sunshine and cloud, or fog, 

 occur at the same time. They appear when, from an elevated 

 position, the shadow of an observer is projected by the Sun 

 on a cloud or fog ; he sees the head encircled by a glory or 

 luminous ring, diminishing in brightness as it leaves the head 

 as a centre. A phenomenon substantially similar to the 

 anthelia occurs when, the Sun being near the horizon, the 

 observer sees an aureola surrounding the shadow of his head 

 cast upon grass or corn moistened with dew." 



Some of your readers have perhaps witnessed similar 

 phenomena elsewhere, and any information that they can 

 furnish on the subject would be very acceptable. 



Rangoon (Burma). 



J. C. Clancey. 



Note. — On the moonlit nights of the last week of May, 

 1912, some days after the earthquake shock of the 23rd May, 

 a phenomenon, believed to be that known as Anthelia or 

 Glories, but novel to the observers, was seen at Maymyo. 



There were heavy dews at the time and as soon as it was 

 sufficiently dark for the moon to cast distinct shadows the 

 observer noticed that on the dewy short grass of the lawn a 

 patch of light appeared round the shadow of the head, while 

 there was also an outer circle of light with the head shadow as 

 a centre and with a radius of the length of the observer's 

 shadow. 



The patch of light or inner halo had no definite outline, but 

 was brightest alongside the shadow of the head and was 

 distinct over a space with about twice the diameter of the 

 head shadow. 



The illuminated band of the outer halo averaged perhaps a 

 foot in width. It was narrower when the Moon was high, and 

 was then bright and distinct throughout its circumference. 



Both halos were white, and it was noticed that the head 

 halo and outer halo attached to each person's shadow was 

 visible to that person only. Another person looking over the 

 first person's shoulder could not see that person's halo, though 

 he could at the same time see his own distinctly. 



At the time of the phenomenon there appeared to be nothing 

 unusual in the appearance of the Moon or sky. The former 

 was bright and the latter clear. 



The phenomenon was first noticed on Tuesday, 28th May, 

 and was observed for several nights. On the night of Friday, 

 31st May, at 10 p.m., it was seen by a number of persons and 

 was then very distinct. 



Maymyo. H. M. S. M. 



