3 68 



NATURE 



\_Feb. 19, 1 ! 



A multitude of new species are described, and others 

 already noticed have been more fully investigated and 

 the details given. Naturally, many European species 

 occur also in America. For these the author has mainly 

 (as is acknowledged) made use of Mr. Buckton' s yet incom- 

 plete monograph of the British species, adopting also the 

 latter author's somewhat unscientific form of bibliographi- 

 cal and synonymic quotation. Some very glaring typo- 

 graphical errors are corrected, but only in the place where 

 they first occur, although constantly recurring ; others 

 almost equally important are not noticed. 



Zar Kcmitniss dcr Fauna des untcrsten Lias in Jen 

 Nordalpcn. Von Dr. Neumayer. (Vienna, 1879.) 



English geologists who are interested in the study of the 

 Infralias, will welcome this latest contribution to science 

 by the indefatigable palaeontologist of Vienna. The 

 fossils described have been obtained principally from 

 •three localities — Pfonsjoch, in the Northern Tyrol, 

 Breitenberg, in the Osterhorn group, and Zlambach in 

 the Traunthale. Among the sixty-six forms here noticed, 

 a large proportion are either identical with species which 

 have been described in Western Europe or present such 

 slight points of difference that Dr. Neumayer has not felt 

 himself warranted in giving them distinct names. It is 

 very interesting to find how close is the agreement in the 

 general characters of the fossils of these Infralias beds in 

 the Mediterranean province with the fauna of the strata 

 on the same horizon in England, France, and Swabia. 

 As in Western Europe, so in the Alpine province, we find 

 the numerous varieties of Ammonites (Aegoceras) an»n- 

 latus and planorbis, especially characterising the zone by 

 their great abundance ; while Ostrea arietis, Lima 

 punctata, L. gigantea, L. succincta, Modiola psilonoti, 

 Myoconclia psilonoti, and Unicardium cardioides, are 

 associated with these ammonites in both areas. Besides 

 these familiar forms there occur, however, some others 

 which are quite unknown in Western Europe. Dr. 

 Neumayer's monograph is illustrated with seven well- 

 executed lithographic plates, and is a very valuable 

 contribution to our knowledge of the Jurassic formation in 

 the Alps. 



J. W. J. 



Africa Past and Present. By an Old Resident. (London : 

 Hodder and Stoughton, 1879.) 



In "Africa Past and Present " the writer carries us back 

 to the time when Herodotus, collecting material for his 

 history, in the absence of written documents, travelled to 

 Africa. Then follow chapters on enterprising Arabs, who 

 penetrated into the interior of the country at afar distant 

 period, and on the Portuguese early English and French 

 discoveries. Accounts are given of the travellers who 

 were sent out by the African Association to explore the 

 interior of the country, prominent among whom were 

 Mungo Park, "whose melancholy fate did not damp the 

 ardent desire of the British public for further information 

 concerning the interior of the great continent." Then 

 follow descriptions of the more recent adventures and 

 discoveries of Speke, Grant, Baker, Livingstone, and 

 others, though the author makes no reference to the 

 important work done by recent German explorers. 

 The latter half of the book is devoted to the history 

 and physical geography of the country, the author taking 

 each division and giving topographical details of it, 

 and speaking of its climate, resources, productions, and 

 character, manners, and social condition of its in- 

 habitants. The book is intended as a handbook for 

 missionaries, merchants, travellers, and emigrants who 

 •wish for information about Africa. As such it will be 

 useful. The book has many illustrations and a map 

 of the country. It has also the advantage of being cheap 

 and portable. 



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. No 

 notice is taken of anonymous communications, 



[ The 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 ensure the appearance even of com- 

 munications containing interesting and novel facts.] 



Ice-Crystals 



I have been prevented by other work from thanking your 

 correspondents who offered explanations of the peculiar forms 

 taken by ice-crystals upon rotten ligneous fibre. 



Will you, however, allow me to say that the explanation 

 offered is one respecting which I am very sceptical. 



That explanation is that the long filaments, like spun glass, 

 are merely the result of the internal freezing of the moisture in 

 the substance of the wood and of the expansive force of that 

 freezing pressing the ice thus formed through the pores of the 

 wood. 



My impression is that if this were the cause the expansive 

 force would be sufficient to destroy the ligneous fibre altogether, 

 and break it up. I question also whether there are any pores or 

 tubes of the kind and size required by this theory running in the 

 direction of the medullary rays. Lastly, as upright arborescent 

 forms of ice-crystal are formed upon dry wood and upon other 

 substances, which cannot possibly be due to any such cause, I 

 am inclined to think that this particular form is determined by 

 some other cause than the one suggested. The filaments are 

 much too long and much too crystalline in structure to be the 

 mere result of extrusion from an internal mass of ice. 



Argyll Lodge, Kensington, February 14 ARGYLL 



Kcenig's Collection at the Philadelphia Exhibition 



My attention has just been drawn to the fact that a report has 

 recently been circulated in London to the effect that the splendid 

 collection of acoustic apparatus exhibited by Koenig, of Paris, 

 at the Centennial Exhibition of 1876, had been retained in this 

 country for the Stevens Institute of Technology, under promise 

 of payment, and that nothing had been paid for it. 



As regards the Stevens Institute, I have to say that the report 

 is utterly without foundation. 



We hive never had one of the instruments in our charge, nor 

 has a word ever been said about purchasing it for our use. 



The collection was, in fact, removed from the Centennial 

 building to the University of Pennsylvania at Philadelphia, 

 which is about one hundred miles from here, where it now 

 remains, and it has been currently reported that a gentleman in 

 Philadelphia had presented it to the said University. As to that 

 part of the story I know nothing, but I do know absolutely that 

 the Stevens Institute of Technology has never had anything 

 directly or indirectly to do with the matter. 



Henry Morton 



Stevens Institute of Technology, Hoboken, New Jersey, 

 February 4 



" Scientific Jokes" 



I DO not know who your correspondent " G. H." may be, but I 

 should surmise from the tone of his letter that he is somewhat of 

 a beginner in science, and that he is so proud of his acquaintance 

 with certain elementary propositions in thermodynamics, that he 

 is on the qui five to detect in others an ignorance of them. In 

 my opinion the fair meaning of the passage objected to, when 

 read with its context, is that the author is drawing a parallel 

 between temperature in heat and potential in electricity (between 

 which there are striking analogies), and that the words to which 

 your correspondent refers are purposely employed to prevent 

 any one imagining (as " G. H." seems to have done) that it was 

 intended to represent the energy of heat as the product of heat 

 and temperature in the same manner as that of electricity is the 

 product of quantity and potential. Temperature is treated as 

 inseparable from heat and nothing more, just as potential is 

 inseparable from electricity, and this is not an unscientific view 

 of the matter. 



The latter part of the letter relating to the theory of terrestrial 

 magnetism, propounded by Professors Ayrton and Perry, is, I 



