58o 



NATURE 



[July 8, 1920 



Animal Heroes : Being the Histories of a Cat, a 

 Dog, a Pigeon, a Lynx, two Wolves, and a 

 Reindeer. By Ernest Thompson Seton. Fourth 

 impression. Pp. 363. (London : Constable and 

 Co., Ltd., 1920.) Price 85. 6d. net. 

 This lively and generously illustrated book begins 

 with the story of four of the lives of a " Royal 

 Analostan " cat — we were a little afraid that there 

 wene to be nine — which, in virtue of considerable 

 worldly wisdom, got on well against heavy odds. 

 "But in spite of her prosperity, her social posi- 

 tion, her royal name and fake pedigree, the great- 

 est pleasure in her life is to slip out and go 

 a-slumming in the gloaming, for now, as in her 

 previous lives, she is at heart, and likely to be, 

 nothing but a dirty little Slum Cat." The second 

 story tells of the ability of a homing pigeon and of 

 its successful education. "The hardest of all work 

 is over the sea, for there is no chance of aid from 

 landmarks ; and the hardest of all times at sea is 

 in fog, for then even the sun is blotted out and 

 there is nothing whatever for guidance. With 

 memory, sight, and hearing unavailable, the 

 Homer has one thing left, and herein is his great 

 strength, the inborn sense of direction. There is 

 only one thing that can destroy this, and that is 

 fear, hence the necessity of a stout little heart 

 between these noble wings." This is a fair 

 sample of the more reflective passages in the book, 

 and it is too easy-going. There is a stronger note 

 in the two descriptive studies of wolves, for Mr. 

 Thompson Seton excels in proportion to the wild- 

 ness of the scenery and of the dramatis personae. 

 The other subjects are "The Boy and the Lynx," 

 "The History of a Jack-Rabbit," "The Story of 

 a Bull-Terrier," and "The White Reindeer." The 

 author is an artist in reading the man into the 

 beast — a great art, but a dangerous one ; and we 

 are afraid that some of the book is in the danger 

 zone. But those who recoil from " apsychic " 

 biology will probably agree that Mr. Thompson 

 Seton's anthropomorphic faults lean to virtue's 

 side. 



The Year-book of the Scientific and Learned 

 Societies of Great Britain and Ireland. Thirty- 

 sixth Annual Issue. Pp. viii + 336. (London: 

 C. Griffin and Co., Ltd., 1919.) Price 125. 6d. 

 net. 

 As is well known, this invaluable year-book gives 

 official particulars and records of work not only 

 of scientific societies in the British Isles, but also 

 of such institutions as the Imperial Institute, 

 Meteorological Office, National Physical Labora- 

 tory, Rothamsted Experimental Station, etc. 

 Titles are given of papers read during the session 

 1918-19, and twenty-six new societies have been 

 added to the comprehensive list of those surveyed 

 in this volume. The work is one which we con- 

 tinually consult, and it is an essential volume for 

 the reference library of every newspaper, institu- 

 tion, college, or club which desires to provide its 

 staff or members with accurate particulars of _ the 

 officers and activities of scientific organisations 

 throughout the kingdom. 



, NO. 2645, VOL. 105] 



Letters to the Editor. 



[The Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. 'No notice is 

 taken of anonymous communications.] 



Weather Forecasts and Meteorology. 



The experience gained during the last few years in 

 aerial navigation nas shown, among other' things, 

 that weather forecasts, in these latitudes at am rate, 

 are trustworthy only tor a few hours in advance, and 

 not always that. 



If weather forecasting were at all accurate for a 

 day or two ahead, it would be possible to make a 

 correct weather-chart for to-morrow from the informa- 

 tion received to-day. This has never yet been done, 

 and it seems unliKely that it ever can be done, for 

 the simple reason that in latitudes higher than 30° or 

 thereabouts the conditions of the tio^v of the air are 

 those of the permanent instability which characterises 

 a stream^ exposed to the influence of surface friction 

 at a velocity greater than that compatible with 

 lamellar flow. 



The unstable motion referred to consists of eddying 

 motion superposed on a general drift, the eddies them- 

 selves being of all sizes and in all stages of growth 

 and decay — some showing actual rotation, others 

 being merely distinguishable by diflerences of velocity 

 and direction. Eddies, when formed, have a certain 

 individual life, generally of not many hours' duration, 

 though in some cases there may be maintaining causes 

 which will prolong their existence for days. The 

 deviations of their courses {i.e. the path of their 

 centres) from the average direction of the stream 

 depend chiefly on the state and intensity of the other 

 eddies in the neighbourhood, and, within wide limits, 

 must be treated as a matter of pure chance. 



Let anyone watch the motes of dust in the air 

 illuminated by a beam of sunlight passing through a 

 slit. They may all, on the whole, be drifting in some 

 one direction, but combined with the general drift 

 there will be irregular eddying motions, some quick, 

 some slow, but deviating largely from the average 

 for the whole. Much the same sort of thing on a 

 large scale takes place in the atmosphere, and a 

 weather forecast professes to determine from the 

 motion over a certain area and at a certain time, 

 together with the then existing variations, what the 

 future motions will be. 



For a time so short that the eddying motions pre- 

 serve their respective characters this can be done, but 

 not for longer periods, the causes which alter, existing 

 eddies and develop new ones being incalculable. 



If the weather prophet makes no observations what- 

 ever, but is content to say that "to-morrow will be 

 like to-day," he will be right rather more than sixty 

 times out of a hundred. With all the information 

 which can be obtained, by telegraph or otherwise, 

 he may add 10 or 15 per cent, to his correct predictions 

 for twentv-four hours ahead. 



The Meteorological Office, I believe, claims rather 

 a better average than this, but its forecasts are often 

 so vague (e.g. "Wind moderate, strong to a gale at 

 times in places. Fair, but with some cloud and rain. 

 Temperature moderate") that almost any sort of 

 weather might be said to fulfil the prediction. 



The proper test of the value of forecasts for a day 

 in advance w-ould be to prepare a chart for that day 

 and to nublish it side bv side with one formed from 



