192 



NA TURE 



I /line 26, 1884 



much less important. Hence the grander phases of ocean 

 , it ulation exi ept 111 so far as they depend on winds, and 

 therefore on atmospheric circulation) are much more 

 dependent upon polar cold than upon tropical heat. On 

 the other hand, those of atmospheric circulation depend 

 more upon tropical heat than on polar cold. For the 

 great temperature effects are produced mainly at the 

 upper surface of the ocean, and at the lower surface of 

 the atmosphere. Hence, if there were no great modifying 

 causes, we should expect to find (on the whole) the lower 

 water, as well as the lower air, coming from both sides 

 towards the equator, and the upper currents of each 

 flowing to the poles." 



Chapter XXI. is -entitled "Elements of Thermody- 

 namics." The subject is nevertheless treated in a very 

 complete manner, and is evidently regarded by our author 

 as something in the shape of a /leader. We gather this 

 from the Aery characteristic invitation to take the leap 

 which is addressed to the student in Art. 3S1. We shall 

 not, however, repeat the invitation, but rather leave the 

 ! to find it nut for himself and then— take the leap. 



Let us conclude with one more quotation : — 



" We have merely to think of the ideas which we try to 

 express by such words as Time, Space, and Matter, to see 

 that, however far discovery may be pushed, our little 

 'clearing' can never form more than an infinitesimal 

 fraction of the 'boundless prairie.' No part of this, how- 

 ever, can strictly be called inaccessible to unaided human 

 reason, if time and patience fail not. But far beyond in 

 one sense, though in another sense ever intimately present 

 with us, are the higher mysteries of the true Metaphysic, 

 of which our senses and our reason, unaided, are alike 

 unable to gain us any information." 



While cordially indorsing these views, the writer of this 

 notice would remark how admirably fitted is such a 

 science as Physics for the discipline of the human mind. 

 It possesses that boundlessness which is the ultimate 

 characteristic of all true knowledge, and this is ,0 

 1 is that few are bold enough to represent our " little 

 Physical clearing" as bounded by an " impenetrable wall" 

 <>r by the " abyss." 



The scientific incendiary (to change the metaphor 



somewhat) prefers to confine himself to regions where 



there 1 >llei tion of inflammable materials, until 



at length his attempts are brought to an end by the 



1 aus stream of cold water with which the physicist is 



r ,e the scene of his exploits. 



Balfi iur Si ewar i 



OUR ROOK SHELF 

 Beitrdge :///■ Kenntniss der Liasischen Brachiopodenjauna 

 von Siidtyrol unit Venetien. Von Hyppolyt Haas, 

 Dr. Phil., Privat-doccnt an der Universitat Kiel. Mit 4 

 lithographirten tafeln. 4to. (Kiel: Lipsius und Tischer, 

 18S4.) 

 THIS is one of the numerous works which have been pub- 

 lished during the last half century on the fossil forms of 

 Brachiopoda, that most ancient, abundant, and anomalous 

 class of the Invertebrata. Dr. Davidson has devoted the 

 greater part of a tolerably long life to the study of this 

 exceedingly interesting group : and the volume of the 

 Pateontographical Society's publications for the present 

 \ear will complete and close his valuable labours on the 

 fossil Brachiopoda of Great Britain. He has kindly fur- 

 nished me with the following critical notice of Dr. Haas's 

 work, the title of which is above given : — 



taas describes in his memoir some 40 species of 



Liassic Brachiopoda, and of which number 12 are new. 

 In four admirably drawn quarto plates he gives figures of 

 32 species. The Liassic Brachiopoda from South Tyrol 

 and Venctia are very remarkable, and have in part been 

 described and beautifully illustrated by Gemmellaro 

 B61 kh. Uhlig, Meneghini, Canavari, Oppel, Zittel, and 

 Schmid ; Waldheimia perforata, Pictte, and Spiriferina 

 Fiiit rat a, Schl., being the only species out of the numbei 

 that occur in the Liassic rocks of Great Britain. Dr. 

 Haas's work adds much to our knowledge with respect to 

 the Liassic Brachiopoda, and his descriptions have been 

 carefully drawn up. In tSSi and 1882 Dr. H. Haas and 

 Dr. Camille Petri published a very important work, en- 

 titled ' Die Brachiopoden der Juraformation von Elsass- 

 Lothringen,' accompanied by 18 beautifully drawn quarto 

 plates. In this work the authors describe some 92 spei i< 

 from the Lias and Inferior Oolite, and of which a large 

 proportion occur likewise in our British rocks. It is to 

 be hoped that Dr. Haas will continue his valuable re- 

 searches among the Brachiopoda." 



" Non mens hie sermo ! " 



J. GWYN JEFFKF.VS 



Tricycles of the Year 1884. By H. H. Griffin. (London: 



L. Upcott Gill, 1884.) 

 WHATEVER improvement in health and strength ma; 

 have resulted from the now prevalent exercise of cycling, 

 there seems to be a mental improvement, for a knowledge 

 of the science of mechanics is more widely spread, or at 

 an) rate there is a more general desire to understand this 

 science in so far as its application to the bicycle and 

 tricycle is concerned. For this reason such a book as 

 Mr. Griffin's " Tricycles of the Year" is likely to be of 

 value, for in it he describes in simple language most of 

 the tricycles which can now be obtained, giving particulars 

 of dimensions and weight, and other information which a 

 cyclist may require. 



It is a pity that many well-known machines are not so 

 much as mentioned, among which are the " Rudge," the 

 " Cheylesmore," and the direct-action machines. Is it that 

 there has been no improvement in any of these since last 

 year? If so, why should the "Oarsman" be omitted 01 

 some others be described at length ? 



The good qualities and advantages of each machine 

 are set forth plainly enough, while the defects are left to 

 be discovered by riders. The author has no doubt acted 

 wisely here : it would be next to impossible in dealing 

 with such a multitude of often similar machines to make 

 comparisons which cyclists who hold opposite opinions 

 would not consider unfair. 



The action of parts that are peculiar to any machine is 

 carefully described, figures being inserted where necessary 

 to make the text more comprehensible. The general 

 appearance which many tricycles present is shown by a 

 series of woodcuts. 



Bicycles are not discussed, as they form the subject of 

 a corresponding work. C. V. B. 



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, re/ eted manuscripts. 

 No notice is taken of anonymous communications, 

 [ Th ! Editor urgently requests correspondents to keep their letters 

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

 that it is impossible otherwise to insure the appearance even 

 of communications containing interesting and novel facts.] 



Chalk and the " Origin and Distribution of Deep-Sea 



Deposits " 



I looked forward with great interest to the conclusion of 



Messrs. Murray and Renard's "Origin and Distribution of 



Deep-Sea Deposits," hoping that some useful comparisons would 



