February 20, 1902] 



NATURE 



567 



The Moon and Thunderstorms. 



It is known that several meteorologists have affirmed a con- 

 nection between thunderstorms and the lunar phases. In his 

 recent admirable " Lehrbuch," Dr. Ilann appears to favour this 

 idea somewhat, and he gives some account of researches on the 

 subject (p. 662). 



I do not remember to have seen the Greenwich data 

 treated from this point of view. It might, therefore, interest 

 your readers to see how days on which thunder was heard 

 at Greenwich in the last thirteen years (summer half) are dis- 

 tributed in the week about new moon, about first quarter, &c. 

 This is shown in the diagram, where each dot represents one 

 such day. The number of dots in each case is given below ; 

 and in the curve, each point represents the sum of three 

 consecutive members of this series. 



6 blXloio (>1 6b(,T Ti/ 7i-9 4» "^-i-J-Y ^S'9S lo 



It will be seen that the extremes come about new moon 

 ■(maximum) and about midway between full moon and last 

 quarter (minimum). While the three-day group commencing 

 with second after full moon had 9, that about new moon had 32 

 ■ — nearly four times as many. 



This curve might be usefully compared with that, similarly ob- 

 tained, for wet days (or days with 0'5 in. or more) at Greenwich, 

 in twenty-four yeais (given in Nature of August 29, 1901). 



Arranging those 1S2 days by weeks and reckoning per- 

 centages, we have : — 



Week.->bout ist Qr. Full Moon. 4th (Jr. 



New Moon. 



57 41 40 44 



Per cent. ... 31 23 22 24 



The latter figures may be compared with those given in 

 Hann's work for 



N. M. ist Qr. K. M. 4th Qr. 



KremsmUnsler (Wagner) 264 274 209 253 

 Aix la Chapelle (Polls) ... 269 275 21-5 241 

 Batavia (van d. Stok) ... 27-4 24-5 242 23-9 

 All agree in showing a larger percentage about new moon 

 than about full moon, and in the two earlier phases than in the 

 two later. The values for Kremsmimster and Aix are for much 

 longer periods, and it is possible that a larger induction for 

 Greenwich might bring out still closer agreement. The group- 

 ing by weeks, in the case of (Greenwich, seems hardly to do 

 justice to the contrast presented. It may be well, further, to 

 remember that a 26-day period in thunderstorms, corresponding 

 ■to the sun's rotation, has been affirmed. 



Sidmouth, February 6. Alex. B. MacDowall. 



NO. 1686, VOL. 65] 



Progressive Variation in the Malayan Peacock- 

 Pheasant. 



In looking over the specimens of this species (Polypkctnim 

 bicakaratuin) in the Indian Museum, I have come across a 

 most interesting skin of an adult male, showing variation in the 

 direction of greater ornamenlation. Normally, this peacock- 

 pheasant has ocelli only on the wings and tail and the upper 

 part of the back ; but in the present specimen several of the 

 black-speckled buff feathers of the back, immediately below the 

 ocellated region, have clusters of the small spots richly glossed 

 with green like the ocelli, the rest of the black speckling of the 

 feather remaining normal. The green specks are always near 

 the end of the feather, in the position occupied by the ocelli. 

 Furthermore, this bird has the long under-tail-coverts deco- 

 rated near the tip of the outer webs with a not very bright 

 green-glossed ocellus, the inner webs merely showing black 

 patches, such as are normal on both webs of these feathers in 

 other specimens. Thus this individual presents on the upper 

 surface a variation which might be advantageous in se.xual selec- 

 tion, and beneath a similar enhancement of beauty which could 

 hardly be of any use, since the Polyplectrons show off in an 

 attitude which prevents any display of the under-tail-coverts. 

 It is therefore interesting as showing how the beauty of a 

 species might be enhanced both with and without the assistance 

 of preferential mating on the part of the females. 



F. Finn. 



Indian Museum, Calcutta, January 30. 



The Inheritance of Mental Characters. 



Further discussion of this subject {cf. p. 245) should per- 

 haps be postponed until the appearance of Prof. Pearson's 

 detailed paper. Possibly, however, it , may be permissible to 

 discuss briefly Prof. Pearson's reply to my criticism. 



( 1 ) As to the possibility of proving the ' ' soul " factor to be a 

 reality, I would say that it may be possible some day to estimate 

 very exactly the value of the other two factors (heredity and 

 environment), and it will be significant if there is then found to 

 be a residuum not accounted for. This line of reasonmg is not 

 new ; compare A. R. Wallace, " D.irwinism," chap. xv. 



(2) It seems to me very likely that the correlation between 

 the mental characters of brothers would be less than between 

 the physical, if only the factor of heredity were considered. 

 It does not follow from this that the mental characters are less 

 inherited, taking the race as a whole, but only that they are less 

 evenly inherited, so that the true measure of inheritance could 

 only be determined by studying a number of successive genera- 

 tions. I tried to set this forth in the paragraph which Prof. 

 Pearson says he cannot understand. 



(3) There are, however, other disturbing influences. Even at 

 birth, we must believe that we have not the simple product of 

 heredity, as has been well explained lately by Prof. Ewart {Sci. 

 Trans. Roy. Dublin Soc, October 1901, p. 366). Again, the 

 several faculties do not mature at the same age, so that 

 statistics based on children "in public schools, high schools, 

 secondary and primary schools of all classes" cannot be strictly 

 comparable, nor does it seem possible, in the case of mental 

 traits, to make definite allowance for age, as can be done with 

 more or less accuracy in the case of physical characters. 



T. D. A. CoCIvERELL. 

 East Las Vegas, New Mexico, U..S.A., February i. 



ICE LAN D."^ 



FEW parts of the earth's surface possess so strange a 

 fascination, at once attractive and repellent, as that 

 large island which, away to the north -west of Europe, 

 stands between the Atlantic and the Arctic Ocean. Its 

 language and literature, its connection with the northern 

 mythology, the antiquity and continuity of its annals, and 

 its quaint customs and traditions have given it a special 

 place in the history of nations. The strange aspect of its 

 i surface and climate — the home of frost and fire, the scene of 

 some of the most colossal volcanic eruptions which man 

 has ever witnessed, the site of vast snow-fields and 

 glaciers, a region shaken with earthquakes, devastated by 



1 1 "Geological Map of Iceland." By Th. Thoroddsen. .Surveyed in 

 I the years 1881-1898. Edited by the Carlsberg Fund. (Copenhagen, root.) 



