ng: 



NA TURE 



{Jan. 28, I i 



detail. Tlie second part glances at the same facts, so far 

 as they are found manifested in the lower animals, more 

 especially in the Arthropods, Molhisca, and Worms. 

 Many of the woodcut illustrations are from original 

 drawings, and of these those representing the muscles 

 engaged in prehension and mastication are very good. 



Animal Life on tlic Fann. By Prof G. T. Brown, 

 Agricultural Department, Privy Council. (London : 

 Bradbury and Agnew.) 



This is the last of a series of eight convenient hand- 

 books covering the whole field of agricultural study. Dr. 

 Masters's " Plant Life on the Farm" is ably followed by 

 the excellent little book from the pen of Prof Brown ; and 

 what may at first appear in the light of omissions in a 

 treatise upon animal life as seen upon farms is at once 

 corrected by the previously-published account of the live 

 stock of the farm. Thus, while the subject of crops of 

 the farm and live stock of the farm were ably treated, 

 there was still room for more purely scientific writers, 

 such as Dr. Masters and Prof. Brown, to treat of life more 

 as biologists than as practical farmers. Accordingly, 

 what is true of life on the farm is in many respects true 

 of life in the forest and life in the city ; but this does not 

 detract from the value of facts about life wherever it may 

 be found. It was probably an agreeable task to the 

 writer to put this little volume together. It is full of 

 matter with which he is very familiar, and which he is 

 able to present with that admirable clearness and pre- 

 cision which has always characterised both his oral and 

 written teaching. Commencing with the two opposite 

 conditions of life, and death, as abstractions, we are 

 pleasantly led to the consideration of the beginnings 

 of life in the egg, and by a natural progress to a 

 popular, but at the same time accurate, description of 

 tissues, organs, and functions, which carry the reader 

 through about two-thirds of the book. The remaining 

 third is devoted to the peculiarities of domesticated 

 animals, and in fact becomes more thoroughly specialised 

 upon the farm. The variability, the precocity, the deli- 

 cacy, the plasticity of domesticated animals are each 

 dealt with by a master hand, and illustrated by examples 

 taken from the experience of breeders and our great 

 agricultural societies. 



LETTERS TO THE EDITOR 



\^The Editordoes not liold himself responsible/or opinionsexpressed 

 by his correspondents. Neither can he undertake to retjtrn^ 

 or to correspond with the writers of, rejected manuscripts. 

 No notice is taken of anonymous communicatiotis, 



[The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressjire on his space is so great 

 that it is impossible otherwise to insure the appearance even 

 of communications containinginterestivg and novel facts.'\ 



Iridescent Clouds 



In a letter published in Nature for January 7 (p. 220), I 

 tried to describe the appearance of the iridescent clouds as seen 

 here on the afternoon of December 2S. The phenomenon \>as 

 repeated on December 29 and 31. On December 30, and again 

 on January i, tlie sky was overcast, but since then, though I 

 have looked for them at different times of the day, and especially 

 about sunrise and sunset, I have seen no further trace of iridescent 

 clouds. 



What struck me as most remarkable about them was, not the 

 prevalent colour which they have been said to possess (see pp. 

 199, 219), for I cannot point out any as being peculiar to them, 

 but the changes of colour undergone, often rapidly, by each 

 individual cloud. As a record of these changes in the few 

 instances I am able to give may perhaps help to throw some 

 light on the nature and origin of these clouds, I trust I may be 

 excused for occupying so much of your space. 



December 29. — 3.15 p.m., the sun a few degrees from setting, 

 light cloud partly covering the sky, heavy snow-clouds near the 

 horizon. At about 10° north of the sun and at an altitude of 



about 25°, there was a small cloud, 5° in length, consisting of 

 four or five narrow bands nearly parallel to the horizon, all of a 

 faint, but beautiful, violet colour, j Soon after this, it was hidden 

 by snow-clouds. 



3.44. — This cloud was again visible, showing iridescent colours, 

 no longer consisting of bands, but oval in form and slightly 

 inclined to the north. Half a minute later, a branch of the 

 same form and size, but rather more inclined to the north, 

 appeared on the right, very faint, but increasing rapidly in 

 brightness, until it equalled that of the original cloud. The new 

 branch was at first violet, but in part tinged with rose-colour. 

 The original cloud soon, however, began to fade, and by 3.47 

 had disappeared, the remainder being then green, except the 

 upper edge slightly tinged with pink. 



3.50. — The colours almost gone, but I believe the cloud was 

 at this time covered by a thin haze. At 3.52 the cloud was very 

 faint, and white. 



Fig.l. 



3.55. — The colours again appeared, in three bands, blue on 

 the left (nearest the sun), green in the middle, and on the right 

 pink. But, immediately, the colours began to change, the blue 

 and pink to fade, the green band becoming wider and brighter, 

 until, in a few seconds, the whole cloud was green. It grew 

 brighter and brighter until, at 3.57, it shone out a pure beautiful 

 green almost of rainbow-brightness. But, at this moment, the 

 snow-clouds, which had been rising rapidly, passed over it, and 

 heavy driving snow began to fall. 



. At 4.18 the snow-storm was over, and in nearly the same 

 place as the cloud just ' described were two small clouds, each 

 about 5° long, at altitudes of about 20° and 25° respectively. 

 They were faint, and had a slight trace of indefinite colouring. 

 By 4.26 they had both disappeared. 



4,28. — The two clouds again visible, the lower green, and the 

 upper rose-coloured. But the clouds began to fade at once, and 

 a minute later both had disappeared finally, the sky being now, 

 and continuing, quite clear. 



