NATURE 



501 



THURSDAY, APRIL 2, li 



THE METEOROLOGY OF THE ATLAXTIC 

 Deutsche Seewarte. SegelhandbuchfUr den Atlantischen 

 Ozean. Mit einem Atlas von 36 Karten. Heraus- 

 gegeben von der Direktion. Mit zahlreichen in den 

 Text gedruckten Holzschnitten und neun Steindruck- 

 Tafeln. (Hamburg, 1885.) 

 "THE Atlas of the Atlantic which was published by the 

 "Deutsche Seewarte " in 1SS2, has at length, after 

 a term of three years, been joined by the text, which was 

 intended, in the first instance, to have accompanied itj 

 and of which it was described as an appendix. But 

 though separated in their publication by this wide in- 

 terval, in spirit and in sense, at least, the two are indis- 

 solubly linked together, and either one without the other 

 is but an imperfect and mutilated fragment. Of their 

 excellence, now that they are united, it is unnecessary to 

 speak. When Dr. Koppen, with his able coadjutors, 

 writes, and Dr. Xeumayer edits such a work as this 

 physical and meteorological survey of the Atlantic Basin 

 it would be waste of words to say more than that the 

 result of their co-operation must at once take rank as a 

 standard book of reference on this subject. More espe- 

 cially valuable is it in those sections which are descriptive 

 of ascertained facts, and are based to a very great extent 

 on recent, frequently on original observations. The 

 detail of these occupies the largest proportion of the 

 space, leaving but little room for theorising or doubtful 

 matter, and absolutely none for the repetition of those 

 many myths and false statements which have been so 

 often presented to us by successive writers, one blindly 

 copying from another, that we had almost begun — like 

 the poor Hindoo with the mangy cur — to believe in their 

 truth. It is scarcely credible, but is nevertheless a fact, 

 that in this large volume, of nearly 600 closely-printed 

 pages in royal 8vo, there is not a word about ships bound 

 to the West Indies throwing cargoes of horses overboard 

 in the horse-latitudes, which are, however, mentioned as 

 " Rossbreiten " ; and the reader will look in vain for the 

 time-honoured allegation that the winter storms on our 

 own coasts are extensions of the West India hurricanes. 



The name " Belt of Calm " — " Stillengiirtel " — is unfor- 

 tunately preserved ; though the particular " Belt " which 

 has been asserted to exist near the equator is ruthlessly 

 spoken of as "der sogenannte Stillengiirtel ; and the 

 description of those near the tropics gives no countenance 

 to the pestilential doctrine which the name embodies, but 

 is to this effect : — " Two great whirls occupy the tropical 

 and temperate regions of the Atlantic C cean ; each of 

 these has in the centre a maximum air pressure, around 

 which, in accordance with Buys-Ballot's law, the wind 

 circles, in the direction of the daily motion of the sun in 

 the respective hemisphere. The equatorial sides of these 

 whirls are formed of the trade winds, which thus become 

 more polar on the east side of the ocean, whilst on the 

 west side their direction is due east and so passes to 

 equatorial." " In summer the transition between the 

 west wind of the North Atlantic and the trade takes 

 place, on the coast of Portugal and Morocco, through 

 X.W., N., and N.E., and in the opposite sense on the 

 Vol. xxxi.— No. 805 



coast of North America, through S.E., S., and S.W. In 

 winter, on the other hand, the region of high pressure 

 partakes more of the nature of a belt extending from one 

 continent to the other, and the transition is effected in a 

 less regular manner, sometimes with calms, and some- 

 times with one or more stormy veerings of the wind right 

 round the compass" (pp. 87, 91). All this has, of 

 course, been well known to meteorologists for several 

 years, though it has seldom before been clearly and con- 

 cisely stated in a practical work of this nature. It seems 

 therefore the greater pity that the name " Belt of Calm " 

 should have been allowed to remain : and it would almost 

 seem that its baneful influence has led the authors to 

 write : — " On the South American coast, from i°-3° N. 

 latitude, calms and rains prevail almost the whole year 

 through " (p. 65) : a statement which does not fully agree 

 either with the wind charts of the atlas, or with the 

 direction in our English "South American Pilot"; accord- 

 ing to which the variable winds, calms, and rains last 

 only from the end of April to the beginning of July. The 

 exaggeration is in all probability due to a dim recollection 

 of obsolete maps and a theory that ought to be obsolete, 

 but which from time to time revives in the most unex- 

 pected places. To some similar source is perhaps to be 

 assigned the statement that " land and sea breezes are to 

 be found along the whole west coast of Africa from 

 Morocco to the Congo," which is only partially true : on 

 the northern part of this coast, land and sea breezes are, 

 practically speaking, unknown ; though from the Senegal 

 southwards they are regular enough. 



It is impossible not to regret that statements like this 

 should have been loosely hazarded ; for though they are 

 not of much practical importance either way, they tend 

 to raise an unjust suspicion that fanciful theory has been 

 sometimes permitted to dictate the statement of the facts, 

 instead of exact and careful observation. It would have 

 been safer and therefore better to have omitted theorising 

 altogether ; for, however tempting it may be, no one knows 

 better than the learned and distinguished editor of this 

 volume that there is as yet scarcely a single point in 

 theoretical meteorology which can be said to be fixed with 

 absolute certainty, or which can be fully and satisfactorily 

 explained. The question of air pressure is one of these. 

 In the theory of meteorology no problem is perhaps so 

 interesting and so important : but in the practical appli- 

 cation of rules to which the barometer is a guide, the 

 cause of the variations of the barometer is of no import- 

 ance whatever. The authors of this book are agreed in 

 the opinion that the pressure of the air at any place 

 depends solely on the weight of the superimposed column 

 of air, and that this weight is dependent on temperature. 

 A great many meteorologists hold this opinion ; but 

 many, on the other hand, do not ; and, as has been said, 

 there is room to doubt. Temperature alone does not 

 seem to offer any explanation of the barometric maxima 

 near the tropics, or of the barometric minimum near 

 Iceland; still less does.it offer any explanation of what 

 Maury first called " The Barometric Anomaly at the foot 

 of the Andes " — the high pressure which has been ob- 

 served, amidst sweltering heat and extreme humidity, in 

 the valley of the Amazon. 



But this is irrelevant to the main purpose of the 

 '' Segelhandbuch," and does not at all detract from its 



