OlTORBR, 1001.] 



KNOWLEDGE. 



231 



Hf ttrrs. 



[The Editors do not hold tliemselres responsible for the opinions 

 or statements of correspondents] 



THE Pi>Ti;n',rTi(>x of 



Sl'AC'K. 



Till-: STAK>! TX 



TO TUE EUITOKS OF KNOWLEDGE. 



Sirs, — I have just- been reading the able ai-ticle on 

 "The Brightness of Starlight" in the August number 

 of Knowledge (by J. E. Gore, f.r..\.s.), and have been 

 particularly struck with the very discordant results there 

 obtained, by making use of Dr. Gould's formula, and 

 the method adopted by Jlr. Gore. 



Now this subject of the Distribution of the Stars 

 in Space is one that I have often thought about. I 

 do not refer so nuicli to the distribution of the stai-s 

 according to "" magnitude," as according to their actual 

 ■■ position " in space. Has anything yet been done 

 towards the solution of this question, or if not, have 

 data sufficient for dealing with the subject yet been 

 accumulated ? 



I have a notion that some light may be thrown on 

 the vast subject of " The Evolution of the Galaxy ' 

 by this means; and e.specially, may I add, by concen- 

 trating attention on the comparative sparseness or close- 

 ness of the staj-s at different depths, along the great 

 circle of the gala.xy. Arthur PjD. Mitchell. 



Oxenhope, nr. Keighley. 



[The investigation of the comparative numbers of 

 stars in different directions in space, by means of 

 '■ star gauges," presents little difficulty, but to detennine 

 in addition the relative numbers at different distances 

 is a problem which cannot at present be completely 

 dealt with, because of the want of data as to the dis- 

 tances of a sufficient number of stars. Actual measure- 

 ments of stellar parallax arc very few, and magnitude 

 is no safe guide to stellar distance, so that wc mu.st 

 needs make the best we can of proper motions as a key 

 to the distances of the stars, the stars with large proper 

 motions being supposed relatively near. Even with 

 this basis, however, the distribution of only a few 

 thousands of stars can at present be discussed ; cer- 

 tainly not enough in themselves to indicate the form 

 of our stellar universe. Evidence a.s to the construction 

 of the heavens is, therefore, mainly indirect, and hence 

 the many different views on the subject. Still, one 

 fairly definite result arrived at by Prof. Kaptoyn from 

 a discussion of proper motions is that the sun is a 

 member of a cluster of stars of the same type as itself, 

 and that a den.ser ring of white stars, situated at n 

 gi-eat distance outside this cluster, appears to us ;us the 

 Milky Way.— Eds.] 



SUDDEN BLANCHING OF HUilAN HAIK. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — In his paper on the whitening of the hair of 

 animals, Mr. Lyddeker remarks that, from the evidence, 

 the fa«t of rapid blanching of human hair from emotion 

 must be accepted. It may interest himv and some of 

 your readei's to know of a definite instance of this effect, 

 not from emotion, but from disease. I have recorded 

 it where it is not likely to be generally accessible (" Man, 

 Dis..Nerv. Syst.," Vol. II.). A man, in consequence of 

 an injury', had hsemorrhage over the greater part of 

 the left hemisphere of the brain. During the next 

 two days the haii-s of his beard and moustache on the 

 opposite side, the right, were observed to become paler 



and paler, until they were almost whito at the time 

 of his death on the third day. The change extended 

 up to the middle line and there ceased. A very curious 

 fact is that the pale region was separated fiom 

 the normal brown, by a very narrow darker zone, almost 

 black, in t.lie middle line. Of cour.se emotion must act 

 by itj3 profound derangement of the fuiution of the 

 cortex of the brain. Here we had a like effect produced 

 by an organic influence, occurring under observation, 

 within two days, and limitx^d to the ojjposite side that 

 which the disease woidd influence. The escape of the 

 hair of the scalp, and affection of that of the face, 

 may be ascribed to the special seat of the chief cerebral 

 irritation. The haii-s were mad© pale throughout their 

 length. This, as an absolute fact, a result produced 

 in two days, is significant. The only possible explaiLV 

 tion is that the process, at the root of the hair, by 

 which the normal pigment is produced, is so changed that 

 a material is formed capable of discharging the colour 

 of the pigment, and that this a.scciids the tubular hair 

 and causos it.s effect, at least as far from tiie root a.s 

 the length of the hairs on the face. The degTce to which 

 this chemical process is under the iiinuouce of the 

 nervous system is strikingly obvious, but a similar action 

 is treated on most of the secretoiy processes of the 

 body. Tears arc an illustration. 



The dark line which limited the change is not easy 

 to explain. We know that pigment is apt to accumu- 

 late at the limit of an area in which it is lessened, 

 but wo can hardly apply here the idea of any move- 

 ment of pigment. It would rather seem as thougli, 

 at the median line, at which the innervation of the 

 two sides mingle, the defective influence of the one 

 side, in some way, permitted that of the other side to 

 become excessive. Thei'e arc curious conditions yet to 

 be worked out regarding the median blending of the 

 nerve influence. In the lower part of the face the zone 

 of coalescence is more considerable in extent and degree 



than in many other regions. 



W. R. GowEHS, M.D. 



A TRIPLE RAINBOW. 



TO THE EDITORS OF KNOWLEDC^E. 



Sirs, — The remarks of your correspondent in the last 

 issue of Knowledge on the subject of rainbows, re- 

 called to my mind a very remarkable triple rainbow 

 that was seen at Sutton-oii-Se;i, on the 13th August at 

 4.20 p.m. A terrific hailstorm, accompanied by 

 thunder and lightning, was in progress. In the 

 direction of Louth and Grimolaby, the sun was shining 

 through a cloudless sky, but, due west of Sutton, at an 

 elevation of some forty-five degrees above the horizon, 

 was a magnificent and well defined rainbow, whilst 

 immediately underneath it, as it were, was another, 

 which was not so intense or bright. A third wa,s 

 faintly visible underneath the last-mentioned, the 

 distance separating the three being some 2h°. It 

 seemed to me that there was more than one storm in 

 progress at the time. G. McKenzie Knight. 



43, Millman Street, W.C. 



MOTHING IN SUFFOLK. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — Take it altogether, August is generally my best 

 month with lepidoptera, and I was not disappointed 

 this year at Benaci-e, near Wrentham, in Suffolk. The 

 commoner butterflies were revelling in the bright sun- 

 shine. Peacocks were numerous, and I was fortunate 

 enough t/O take one with the small blue spot under the 



