3IO 



NATURE 



{Jan. IX kSS4 



The brilliant iDorning and evening glows have not yet left ih. 

 In, connection with a letter of one of your correspondents of 

 December 20, 1883, it may he interesting to add that the year 

 17S3, which was characterised by a fearful eruption of Skaptar 

 Jokul in Iceland, and liy remarkable sl(y-colour phenomena 

 similar to those we have lately had, was al o the year in which 

 the last gnat eruption of Asama Yama in Japan took place (^ee 

 Tfansacliotis of llie Asiatic Society of jtaj>a», vol. vi. part ii. 

 p. 327). Asama Yama is the greatest aeti-jc volcano in Japan 

 In connection also with the unusual quantity of aqueous vapour 

 with which the atmosphere has been charged, as proved by the 

 spectroscopic observations of Prof. Michie Smith and others, 

 and the facility that dust particles give for the formation of 

 clouds, and therefore also of sirow, it may be interesting to note 

 that the beginning of the present year has been characterised by 

 the greatest fall of snow that the oldest inhabitants here have 

 known for thirty years. The minimum temperature reached this 

 winter ( - 28° C. on the morning of Decemlier 23 in the neigh- 

 bourhood of the college) is also the lowest for Kingston dining 

 the same period. Prof. Goodwin is now engaged in analysing the 

 snow in order to find out whether similar impurities to those 

 found in Europe and in Java are present. 



■ :.i , D. II. M-\RSII.\I.L 



Queen's University, Kingston, Canada, January ij 



Circular Rainbow seen from a Hill top 

 In the Philosopliical Magazine for January, 1S84, p. 61, is an 

 interSsting article by Prof. Tyndall describing experiments made 

 t<y ptoduce circular rainbows by artificial light and artificial mist, 

 his attention having been attracted to the suliject by an observa- 

 tion made in the Alp^ on one occasion when the shadow of his 

 •i body was projected at night time on to mist by a lamp behind 

 him, and w.as seen to be surrounded by a luminous circle, or halo 

 of light I was so fortunate as to see lately identically the same 

 effect produced with remarkable beauty and completeness in 

 liroad daylight from the summit of a Welsh hill. Staying last 

 week' for a couple of days at Fen-y-Gwryd, near Snowdon, in 

 company with a friend, we walked one morning up the Glydr- 

 Vach. The rain was steadily descending as we left the little inn, 

 • and the thick mist swathed the hill-sides in obliterating folds. Just 

 as we K'ached the summit at noon a slight breeze thinned away 

 the mist in front of the sun, and a burst of sunshine illuminated 

 the hill-tops. Clambering on to the natural cairn which crowns 

 the summit, we looked down into the valley, in which lies the 

 -small lake Llyn Idwal. Along the valley the wind drove masses 

 / -of thin mist and scud, and on this we saw to our surprise the 

 in shadow of the summit with our own sharply-marked shadows pro- 

 'j/irjeeted on it. We waved our arms, and the mystic figures replied 

 i:-)by waving theirs. Surrounding these immense shadowy figures we 

 ■ V'Could see two concentric rainbows completely circular, the centre 

 '; being the shadow of our heads. The colours of the inner rain- 

 .'■ bow were in the order of the primary bow, and the outer was a 

 '. 'Secondary and more faintly-tinted rainbow. During all this 

 ' lime the sun was shining brightly on our backs ; when the wind 

 cleared away the mi-t completely in the valley, the shadows and 

 tlie -rainbows vanished, liut reaopeared when fresh mas es 

 of vapour were blown into the line of our shadows. A very 

 rough attempt at determining the angle subtended by the diameter 

 of the primary bow seemed to show that it was much less than 

 go^ in fact not probably above 20°. This interesting appearance 

 lasted only for a few minutes, as the wind drove up fresh mist 

 in front ot the sun, and the rainbow-circled phantoms disappeared. 

 ,Jt would be interesting to know if any of your readers have ever 

 -11 observed a similar jihenomencn. It has, I believe, been seen 

 '■:■ byballoonists when the altitude of the sun is great and a layer 

 •J ''of tuist and cloud lies beneath. Sh.adows thrown on mist are 

 com'mon ; but this rainbow addition was new, not only to nie, but 

 to liy friend, and his mountaineering experience has been very 

 considerable. J. A. Fleming 



IO lino Vl TT - T-,- - T.r 11 • 



, ,,\ " Unconscious Bias in Walking 



Mr. Larden's letter in your issue of the 17th inst. (p. 262) 



, regawiiu'j "circling to the left in a mist," and the re|ilies of 



, MhStI's. G. H. Darwin and Hawksley, have opened an inlerest- 



h-'inS<l»estion, and one which seems to be but imperfectly under- 



(IjiStood'.i The true explanation of this vexed question has for 



.some, years appeared to me to be that to which it is attributed Ij. 



Mr. Ilaivksley, namely, ine<|uality in the length of the legs. A 



few years ago I ni.ulc .some investigations on the length of the 

 lower limbs in man, the results of which were published in the 

 Journal of Anatomy and Physiotoj^y, vol. xiii. p. 502 (1S79). 1 

 found that of seventy well-authenticated skeletons which I ex- 

 amined, the lower limbs were equal in length in only seven 

 instances, or in 10 |ier cent. ; in twenty-five instances, or 35'8 

 per cent., the ?■/;'/// limb was longer than the left, while in thirty- 

 eight instances, or 543 per cent., the left limb was longer than 

 the right. The left leg I found not only to be more frequently 

 longer than the riglit, but the difference in length lietween the 

 two limbs is greater on an average when the left is the longer. 

 Inequality in length is not confined to any particular age, sex, or 

 race, but seems to be universal in all respects. My observations 

 corroborated those of several American surgeons made on the 

 living subject. The result of one limb being longer than the 

 other will naturally be that a person will unconsciously take a 

 longer step with the longer limb, and consequently will circle to 

 the right or to the left according as the left or right leg is the 

 longer, unless the tendency to deviation is corrected by the eye. 

 The left leg being more frequently the longer, circling should, if 

 this theory of its being due to inequality of the limbs be correct, 

 take place more frequently to the right than to the left. This is 

 precisely what we find to obtain, and in this respect Mes.srs. 

 Larden, Darwin, and Hawks'ey's observations agree with some 

 I made myelf on this question. The diameter of the circle 

 formed by thnse circling to the right should, if my observatimi^ 

 on the skeletons be correct, be less than that made by those 

 circling to the left, since the difference in length between the two 

 limbs is greater when ihe left is the longer. 



To determine the comparative lengths of the right and left 

 arms I made observations on fifty skeletons (the first fifty of 

 those measured to estimate the length of the lower limbs), the 

 results of which I hope to publish soon. In thirty-six of these 

 skeletons, or in 72 per cent, the right arm is longer than the 

 left ; in twelve, or in 24 per cent., the left arm is the longer ; 

 and in two, or 4 per cent., the arms are of equal length. 



On comparingthese measurements of arm and legin the fifty skele- 

 tons the right arm and left legoxs longer than the left arm and right 

 leg in twenty-three instances, or in 46 per cent. ; the le/t arm 

 and right leg are the longer in six instances, or 12 per cent. ; the 

 right anil and right leg are longer than those of the left side of 

 the body in thirteen instances, or 26 per cent. ; the latter are the 

 longer in four instances, or 8 per cent. ; while in the remaining 

 four skeletons the legs are of equal length but the right arm is 

 longer than the left in two instances, and the arms are equal in 

 two cases, but the left leg is the longer in one of those and the 

 right in the other. 



Asymmetry of b: th upper and lower limbs, then, is the rule, 

 and not the exception, as might naturally be supposed. Not 

 knowing the histories of the persons whose skeletons I mea- 

 sured, I am unable to throw any light as to the connection 

 between the proportions of the limbs and right- and left- 

 handedness. 



The particular causes of inequality in the length of the bones of 

 the right and left sides of the body will probably always be more or 

 less a matter of theory. The general cause is, as Mr. Hawksley 

 states, owing to more rapid growth of the one linib than the other. 

 I do not think in the majority of instances it can be atiributed to 

 " illnesses to which we are .subject in early life," as he surmises. 

 Asymmetry is almost invariably found throughout the whole 

 skeleton, for example it is extremely rare to find a skull the two 

 sides of which are absolutely symmetrical. In the limbs it is 

 perhaps more easily attributable to the blood-supply beini; 

 greater to one bone than to another. The nervous sy.-tem may 

 also have to be taken into account as a cause. 



J. G. Garson 



Royal College of Surgeons, London, January 26 



I .-^M left-handed and left-footed ; that is, if there is aiiythin.; 

 to do that requires strength or skill, the left hand is always 

 used ; in football-i-daying, or anything requiring the use of the 

 foot, the left foot gets the work to do. 



I remember being once lost in the woods in America whiK' 

 trying to make a short cut home, and, after walking a go- ' 

 many miles, came upon my own snow-shoe track"on its left side ; 

 thus my bias had been from right to left. 



In a bitter cold day with thick snowdrift and a gale of wind 

 on our " left front,'' as a soldier would say, somi; men were on 

 a sledge journey on Ihe Arctic coast in 1847. It w,as important 



I 



