Nov. 1 8, 1886] 



NA TURE 



desire to add my testimony to Mr. Common's opinion (NATURE, 

 vol. xxxiv. p. 470), that the conditions of the sky must have 

 been wholly different ; 'and where the visibility of the corona is 

 in question, the atmospheric diffusion is all-important. 



We have a most trustworthy criterion of the amount of 

 diffused sky light in the visibility of the moon's limb outside the 

 sun on the coronal background. This appears not to have been 

 observed at all last August, and it may he useful to recall what it 

 looked like under certain almost ideal conditions, which are not 

 likely to recur. 



On July 29, 1878, I observed it in the remarkably clear air of 

 Colorado, and at an altitude of over 14,000 feet, on Pike's Peak, 

 and have a vivid recollection of its appearance then. After 

 totality, and while writing my notes, I heard a call from some 

 bystander of " Look at the moon ! " and glancing up from the 

 paper (with an eye which could not have been in a sensitive 

 condition), saw the moon's limb outside the sun, most con- 

 spicuously defined by a band of pearly light, which faded out- 

 ward, but whose visible width can be estimated from the fact 

 that though I went on intermittently with my notes, and took 

 no other precaution to shield the eye than keeping it in the 

 shadow cast by my telescope stand, the limb continued in my 

 view under these unfavourable circumstances for four miniil'S 

 and twelve seconds after totality was over. A similar duration 

 was recorded by Gen. Myer, the Chief Signal Officer of the 

 United States, who observed near me ; and others at a lower 

 altitude certified to having observed it over three minutes. 

 Something is due to the increased sensitiveness of the eye after 

 the darkness, but there is no doubt that, with even the slight rest 

 of the retina which totality afforded, the phenomenon was such 

 a salient one as to force itself on the attention of those not 

 regarding it. 



This is for a very exceptionally pure sky, of course ; but if, as 

 is stated, observers specially seeking it could not even see the 

 limb a little outside the sun (where the corona is brightest) last 

 August, it seems clear that no conclusions as to its non-visibility 

 under any ordinary means are to be drawn from negative 

 evidence of such a kind. S. P. Langley 



Allegheny Observatory, Allegheny, Pennyslvania 



The Astronomical Theory of the Great Ice Age 



In your issue of November 4 (p. 7), my friend Mr. W. H. S. 

 Monck asks one or two questions relative to the paper on " The 

 Astronomical Theory of the Great Ice Age " which you did me 

 the honour to reprint. 



I take as a convenient unit the mean daily sun heat on one 

 hemisphere. The amount of this unit is indicated by the fact 

 that it continuously maintains the earth's temperature some 300° 

 more or less above what it would be were the sun's heat with- 

 drawn. 



The calculations I gave showed that in the glacial winter the 

 mean daily receipt of heat sunk to 68 of a unit, while in the 

 brief glacial summer the mean d.aily receipt was i'38 unit. 



Considering the magnitude of the unit, it is obvious that 

 fluctuations like this must correspond to vast climatic changes 

 of the kind postulated in the Ice age. Here it seems to me lies 

 the great origina'ing cause of the Ice age, and to dwell on the 

 minor phenomena merely obscures the real point. 



If it be said that no great climatic change takes place because 

 the total sun heat in the year remains the same, then I remark, 

 as I did at the Royal Institution, that on this principle it would 

 be the same thing to give a horse 15 lbs. of oats a day for six 

 months and 5 lbs. a day for the other six months as to give him 

 10 lbs. of oats a day all the year round. Robert S. B.\ll 



The Observatory, co. Dublin, November I \ 



P. S. — I take this opportunity of correcting a misprint in my 

 paper as given in Nature (vol. xxxiv. p. 608). The maxi- 

 mum number of days' difference between summer and winter is 

 465 X eccentricity. 



I Abnormality in Cats' Paws 



Among the many interesting features suggested by the genea- 

 logical table in last week's Nature (p. 40), showing the persist- 

 ence of abnormality in the number of toes on a cat's paw, there is 

 one the significance of which seems not to have occurred to, or 

 to have been passed over by, Mr. Edward Poulton. The pecu- 

 liarity I refer to is the larger percentage of abnormality among 

 the female offspring than anions the male. Taking "Tabby 



V. " as a starting-point, and leaving out one sonormal kitten of 

 which the sex was unnoted, as well as the families of which no 

 particulars are given, the total number of descendants in the 

 table is 36, of which 12 are males and 24 females. Of the 12 

 males, 5 are normal and 7 abnormal, or 41 j and 58J per cent, 

 respectively ; and among the 24 females 7 are normal and 17 

 abnormal, or 29J and ^o% per cent, respectively. Or, to put it 

 in another way, among the 12 normal kittens 5 are males, 7 are 

 females, or4if and 581 per cent, respectively, instead of 33^^ 

 and 66f per cent, as it should be ; and among the abnormals 

 7 are males and 17 females, or 29J and 70^ per cent, instead 

 of 33J and 66j. 



This would seem to indicate either (i) that there is a greater 

 tendency among the male offspring than among the female to 

 revert to the normal condition, or (2) that there is a tendency 

 among the offspring to inherit rather the peculiarities of the 

 parent of their own sex — the male parent in all cases in the 

 table being assumed to be normal. If rather, probably the 

 former, though the latter could easily be tested by a similar set 

 of observations with cats, the male parent of which was abnor- 

 mal, the mothers being in each case normal. 



J. Herbert Hodd 



Hatton Garden, London, E.G., November 15 



Abnormalities in the Vertebral Column of the Common 

 Frog 



In prep.iring skeletons of the frog, my students came acro-s 

 the following abnormalities in the vertebral column, a record of 

 which may be not without interest : — 



(i) In a large Rana icmporaria, the centrum of the eighth 

 vertebra, instead of being biconcave (amphicoelous), is concavo- 

 convex (proccelous), like that of the preceding vertebra. This 

 abnormality I have observed before. 



(2) In a medium-sized Jiaiia temporaria, the eighth and ninth 

 vertebrse are both abnormal. The ninth vertebra h.as well- 

 developed only one transverse jjrocess (the right) for articulation 

 with the ilium. The other (the left) is quite small and ill- 

 shapen ; there is is no anterior zygapophysis on this side. The 

 centrum is anteriorly convex on the right side and concave on 

 the left side. Posteriorly, there is on the right side a convex 

 articular surface for the urostyle ; but on the left side the arti- 

 cular surface is ill-developed and irregular. In the eighth ver- 

 tebra, the left transverse process is abnormally large and strong, 

 has a marked backward direction, and has taken on itself the 

 sacral function on this side, articulating with the ilium. The 

 right transverse process is nearly, but not quite normal. There 

 is a right, but no left, posterior zygapophysis. The anterior end 

 of the centrum is normally concave ; but the posterior end is 

 convex on the left side and concave on the right side. The 

 urostyle and the ilia are slightly modified in accordance with the 

 abnormalities of the vertebra;. C. Lloyd Morgan 



University College, Bristol 



Influence of Wind on Barometric Readings 



Allow me a few words of supplement to Prof. .Vbbe's useful 

 letter in Nature of November 11, p. 29. 



Sir H. James's paper is perhaps better known on this side of 

 the AtLanlic than Prof. Abbe thinks ; but there undoubtedly is 

 too great a tendency to rush into print without previously reading 

 up what has been done. The great bibliographical work which 

 the Signal Office has in hand will do more to check this evil 

 than anything which could be suggested, and hence its enormous 

 importance. 



As regards the application of suction to anemometers, no 

 reference is made to that of Bourdon,' of which my friend Dr. 

 Fines was recently kind enough to show me a very fine specimen 

 at work at his observatory at Perpignan. 



The Cowl Committee of the Sanitary Institute, far from being 

 (as has been imagined) asleep or dead, has been very hard at 

 work, and will in a few months report the result. 



I sincerely hope that Lord Rayleigh will accede to Prof. 

 Abbe's suggestion, but in the interim I append the report of 

 Lord Rayleigh's Southampton paper which appeared in the 

 Aleleoroiogieal Magazine for October 1S82, p. 130 : — 



" ' On the Effect of Wind on the Draught of Chimneys,' by 

 Prof. Lord Rayleigh, F.R.S. 



' See also Lau >hton, " Historical Sketcfi of Anemomctry," Quart. Journ- 

 Roy. .Mct.Soc. vol. viii. (i88a), p. 177. 



