Sept., io 



KNOWI.KDGK .K; SCIl'NTIFIC NM'WS. 



2ig 



close on 13 hands at the shoulder, and is of a bii^ht red 

 bay in colour, with the muzzle, under- parts, and lep;s 

 dazzling white. Its ears (Fig. _s) are relatively much shorter 

 and its hoofs much liroader than in the true wild asses of 

 Africa, from which it also differs markedly in colour, 

 while its cry is soniewhat between a bray and a neigh. 

 In the higher and more open parts of Ladak, kiang are 

 to be seen in large numbers ; and they come galloping 

 round the convoy of the traveller in circles, with their 

 heads carried high in the air, so that the face is almost 

 horizontal. Whether the kiang is entitled to be ranked 

 as a distinct species, or whether it should be regarded 

 merely as a variety of the chigetai or wild ass of Mongolia 

 and the lowlands of Central Asia generally, is a moot 

 point; but, be this as it may, the creature is absolutely 

 confined to the central desert plateau of Tibet, where in 

 winter it develops a coat as thick and rough as a door- 

 mat, in order to afford effectual protection against the 

 rigours of that season at such an altitude. 



r.) 



^ 



Fig. 5. Head of Kiang. 



In addition to the foregoing list of large mammals, 

 Tibet is likewise the home of a number of peculiar species 

 of smaller size. Among these it must, however, suffice 

 to make mention of only two on the present occasion. 

 I'irstly, there is a remarkable species of water-shrew, 

 differing in many respects from the common water-shrew 

 {Neoiiiys fodieiis), and accordingly referred to a genus by 

 itself under the name of Neciogale eli'g(in<;. Of that genus 

 it is the sole known representative. When we are fully 

 acquainted with it, the Tibetan palm-civet (Paradoxuriis 

 laniger), at present known only by a single skin obtained 

 so long ago as 1836, will prove almost as interesting a 

 species, for it is quite probable that it will turn out to be 

 generically distinct from the palm-civets of India and 

 the Malay countries, from which it differs by its woolly 

 coat. 



Such a large number of peculiar generic and specific 

 tjpes of mammals restricted to a continental area of the 

 comparatively small size of the Tibetan plateau is a 

 feature unparalleled elsewhere, and to find an analogous 

 instance we must take the case of an island like Celebes, 

 which has been isolated for ages from all surrounding 

 lands. It would seem, therefore, that Tibet has been 

 similarly isolated, so far as immigration and emigration 

 of its animal fauna is concerned, for a vast period of time ; 

 an insulation due, doubtless, to its great elevation above 

 the sea-level, and the consequent severity of its climate 

 and rarity of its atmosphere. Climatic peculiarities of 

 this nature can only be endured by animals specially 

 adapted to such conditions of existence ; and it is accord- 

 ingly only natural to expect that when once the Tibetan 

 fauna had become modified for the needs of its environ- 

 ment it would have remained permanently isolated from 

 that of the surrounding countries. 



Photography. 



Pure and Applied. 



By Chapman Joni.s, F.I.C, F.C.S., &c. 



Artificial lllitmination. — It seems not unlikely tliat all 

 our present methods of artificial illumination will be 

 regarded as elementary and crude in the not very distant 

 future. We aim at getting enough light, but arc not at 

 all particular as to its quality. When the colour of an 

 artificial light is modified, it is generally with the idea of 

 making the lamp more ornamental, rather than for the 

 sake of the light itself, for shades and globes are made 

 of all varieties of tint. The result is that coloured 

 objects appear difl'erent according to whether they are 

 \-iewed by daylight or lamplight, the variation extending 

 even to the character of the lamplight. For a long time 

 we were contented with analogous photographic discre- 

 pancies, using only plates that render bright yellow and 

 red as if they were dark grey or black, and some dark 

 blues as if they were white, but we are now becoming 

 alive to the importance of such errors. I have a piece 

 of plaid material that has broad stripes of a light brick 

 red, and a dark blue, which if photographed on an 

 ordinary or even an isochromatic plate, shows no trace 

 of the pattern. A photographic falsification of this kind 

 would not be tolerated, but such a change as I noticed a 

 little while ago, when a blue silk dress appeared to be a 

 rich brown by the artificial light provided, would 

 probably either pass unobserved or be regarded as a 

 curious and unavoidable incident. It may be argued 

 that daylight changes, and so indeed it does. Reds are 

 hardly distinguishable from black, and blues and greens 

 become grey as the night approaches, and twilight is the 

 more beautiful because of it. But to bring the changes 

 that are associated with the dying day into the full glare 

 of a brilliant illumination ought to offend our good taste. 

 A step forward in artificial illumination has recently been 

 made by Messrs. W. M. Gardner and A. Dufton in the 

 construction of a lamp for colour matching. They 

 employ an arc light, and by means of suitable media 

 absorb that part of the light that is excessive, and so 

 obtain an illumination which they state " is precisely of 

 the same character as that of good daylight from a north 

 sky, and has the advantage over ordinary daylight of 

 being perfectly uniform and unchangeable." Although 

 intended only for matching colours, the same principle 

 might be applied to ordinary illumination, and this offers 

 a far greater and more important field for such modifi- 

 cations of artificial lights. 



The VariahiUly of JJaylig/il. — The changeable character 

 of daylight has a very large inlluence on photographic 

 work, and therefore must be studied by those who would 

 get better results than are obtained by the careless snap- 

 shotter. As the sun gets low the daylight gets markedly 

 more yellow, and we ha\e from time to time been in- 

 structed that the excessive l>lue sensitiveness of gelatino- 

 bromide plates becomes so far negatived on account of 

 this change that it is not necessary to obviate it by the 

 use of a yellow or orange-coloured screen. Whether (jr 

 not this is so depends on what the photographer wants 

 If he seeks to photograph an evening effect as if it were 

 lit by such light as is given by the sun only when he is 

 high up in the heavens, while the general effect is such as 

 can be obtained only when he approaches the horizon, 

 then he may omit the coloured screen. But if his aim is 

 to photograph the scene before him as it is, there is as 



