170 



NA TURE 



\JDec. 20, i( 



necessary to use the most rigorous means to calculate 

 the position by dead reckoning, so that the errors of 

 steering, &c., may not be augmented by errors in calcu- 

 lation. Such being the case, we regret that Mr. Merrifield 

 has omitted from the chapter on traverse sailing the 

 warning given in Raper that, especially in high latitudes, 

 the differences of longitude should be found on each 

 course, instead of the departures being lumped and the 

 difference of longitude found from the result. 



In the chapter on soundings and tides (No. 10), Mr. 

 Merrifield has published the system of the late Sir Francis 

 Beaufort for ascertaining the height of the tide at any 

 moment provided we know the range and time of high 

 water. This is the method generally adopted by sur- 

 veyors when circumstances prevent their having a tide 

 pole on shore, and is traditionally known amongst them, 

 though not hitherto published. It is fairly accurate when 

 the diurnal inequality is inconsiderable, and we can re- 

 commend it as being sufificient for all practical purposes 

 in finding the depth of water to be added to the soundings 

 on the chart in places like the Bristol and Irish Channels, 

 where it is necessary, owing to the large ranges, to take 

 the state of the tide into consideration in judging the 

 position by soundings in foggy weather, or in calcu- 

 lating when a bank or flat can be safely crossed. The 

 fact that in rivers or harbours certain winds affect the 

 height and that atmospheric pressure also has an influence 

 over tides may be safely ignored in the open sea, as their 

 combined influence would probably never exceed half a 

 fathom, but a range of from three to five fathoms can 

 never be lightly considered by the careful navigator. 



OUR BOOK SHELF 



Farm Insects. Being the Natural History and Economy 



of Insects Injurious to Field Crops, and also those 



which Infest Barns and Granaries, with Suggestions for 



their Destruction. By John Curlis, F.L.S. Pp. 540, 



with 16 Coloured Plates, Royal 8vo. (London : John 



Van Voorst, 1883.) 



This is simply a reissue of Curtis's classical work ; it had 



long been " out of print" in booksellers' phraseology. It 



remains the best book on economic entomology that has 



appeared in this country, and has certainly served as a 



model for the Reports of various State entomologists on 



the other side of the Atlantic. No other author here has 



gone into the question of special injurious insects with the 



same care and minuteness, and it may be said that (with 



the exception of certain Reports issued in America) 



there is no similar collective work faithfully illustrated by 



the author's own pencil. The plates and woodcuts are in 



Curtis's best style, and if he had been an entomological 



artist only, his work would have remained unsurpassed. 



Opinions may be divided as to the desirability of re- 

 issuing such a work " untouched," when so many years 

 have elapsed since the publication of the chapters in the 

 Proceedings of the Royal Agricultural Society that formed 

 its basis. Much and valuable additional information has 

 been obtained since the original articles were written, and 

 very much alter.ition in nomenclature has resulted from 

 the efforts of systematists to place this branch of entomo- 

 logical science on a sounder footing, but the facts remain 

 practically unaltered, and there is the charm of a certain 

 originality in the author's style that any radical reconstruc- 

 tion might 'lave destroyed. 



Nevertheless we do think it a pity that some one could 

 not have been found with sufficient knowledge and courage 

 to re-edit the book and bring it down to date. On the 



other hand, this process might have resulted in the work 

 being no longer " Curtis's Farm Insects." Its value would 

 be destroyed if rewritten, even by the most experienced, 

 and we think the only practicable method of dealing with 

 it in an absolutely new edition would be by means of 

 copious annotations, not by recasting the whole. 



LETTERS TO THE EDITOR 



[ The Editor docs not hold hitiisclf 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 letter i 

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

 that it is impossible ot/icrwise to insure the appearance even 

 of communications containing interesting and novel facts.'\ 



Evolution of the Cetacea 



I AM glad to be able to assure Mr. Searles Wood that I have 

 long been familiar with the specimen ca.]\ed Talaocctus sedgwicki, 

 preserved in the Woodwardian Museum at Cambridge, and have 

 repeatedly examined it with much interest. It is undoubtedly 

 Cetacean, and allied to the genus Bahtnoptera, as Mr. Seeley 

 demonstrated, though differing in smaller size and some other 

 characters from any existing species. As, however, the light il 

 throws upon the evolution of the Cetacea is very small com 

 pared to the time that would have been taken up in discussing 

 its bearings, I did not think it worth while to allude to it 

 in a lecture of which the length was necessarily limited. 

 It is, after all, a mo^t unsatisfactory fragment, as its geological 

 age is, and probably always will remain, a matter of doubt. 

 Allowing, however, the utmost antiquity assigned to it, my argu- 

 ment would rather be strengthened than weakened. Mr. Searles 

 Wood seems to have missed the fact that my chief contention 

 was against the prevalent view that the Cetacea have been de- 

 rived from the Carnivora through the Seals. Any evidence which 

 throv\'S back their origin in time and derives them from some 

 more generalised type of mammals would militate against this 

 view. No one can suppose that the Ungulata originated at the 

 commencement of the Tertiary period, as we know that they 

 were then ali-eady differentiated into great and distinct .sections. 

 Their primitive ancestry must therefore be looked for far back 

 in Mesozoic times. That I thought the Cetacea existed before 

 the Tertiary period I distinctly intimated by suggesting, as an 

 explanation of the absence of their remains in the chalk, that 

 they might then have been inhabitants of great inland waters, 

 but having had so many warnings of the fallacy of negative 

 evidence in geology, I do not yet despair of the discovery of 

 a veritable Cretaceous whale. W. H. Flower 



The Java Eruption 



I HAVE been greatly interested in your note on M. Renard's 

 researches as to the composition of the volcanic material ejected 

 during the recent eruption of Krakatoa. The ashes, as stated, 

 are those of a magma that would have produced an andesite 

 with rhombic pyroxene. Now such an andesite occurs at so 

 many points, and in such immense masses, round the great 

 Pacific "circle of fire," that one is temptfd to ask if it may not 

 specially characterise this important volcanic region. I will, 

 with your permission, briefly refer to some published, and one 

 or two unpublished, facts with regard to the distribution of this 

 andesite (called hypersthene-andesite by Whitman Cross and 

 Iddings, and brouzite-andesite by F. Becke) round the Pacific 

 circle. 



In the Neues Jahrbuch for 1881 {Beilage Band i88i, 467) 

 Dr. Oebbeke describes, under the term augiteandesite, a rock 

 from the Sierra de Mariveles, Luzon. Owing to the kindness 

 of the author, I have a section of this rock before me as I write, 

 and I have little doubt that the strongly pleochroic mineral is 

 mainly, if not entirely, a rhombic pyroxene. Augite, however, 

 is also present. 



Passing to the other side of the Atlantic, we have recent evi- 

 dence to show that a rock of the same type occurs along the line 

 of the Rocky Mountains and the Andes. 



\\\ Bulletin No. \ of the U.S. Geological Survey {\%%l), Mr. 

 Whitman Cross describes a hypersthene-andesite from Buffalo 

 Peaks, Mosquito Range, Colorado. 



