412 



NA TV RE 



[March 2, 1893 



own methods ; and as none will ever become photo- 

 micrographers who have not some ingenuity and en- 

 thusiasm, it is only needful that they be set to work, and 

 they will undoubtedly find their own "best methods." 



This treatise is too general to expect from it more than 

 useful and suggestive hints on the subject of the prepara- 

 tion and mounting of objects ; and the same may be said 

 as to the history of the microscope, which is nevertheless 

 given in an interesting and useful manner. The book 

 will undoubtedly attract many readers, and it will afford 

 help to many who are seeking it ; but we respectfully 

 doubt whether it will enable the elementary reader to 

 fully follow the diffraction theory of microscopic vision, 

 so as to be able to understand its application to the wide 

 range of subjects supposed to be dealt with from that 

 point of view by this sumptuous treatise. 



W, H. Dallinger. 



A UNIVERSITY EXTENSION MANUAL. 

 The EartKs History : an Introduction to Modern Geology. 

 By R. D. Roberts, M.A. (Camb.), D.Sc. (Lond.). With 

 Coloured Maps and Illustrations. (London : John 

 Murray, 1893.) 



THIS is not a large book, and a slightly less ambitious 

 title might have been more appropriate. Certainly it 

 is an introduction to the study of modern geology rather 

 than a history of the earth, for the latter is regarded from 

 a limited point of view. But from the page preceding the 

 frontispiece it appears that the volume is one of a series 

 of " University Extension Manuals." It partakes^ there- 

 fore, of the advantages and disadvantages of this method 

 of disseminating knowledge. 



The topics treated by Dr. Roberts are the progress of 

 geological thought : the beginnings of the earth's history : 

 the modifications of its surface due to forces destructive 

 and reproductive : the movements of its crust, including 

 the action of volcanoes. Finally he deals with the 

 formation of rock masses, and attempts to give — though 

 of necessity this subject is very imperfectly treated — some 

 idea of the evolution of the British Islands. 



The materials employed by the author are not generally 

 novel, for one text-book must draw from much the same 

 storehouse as another, but Dr. Roberts has a lucid and 

 pleasant method of statement, gained no doubt by his ex- 

 perience in the lecture room. One point, however, though 

 it relates to a well-worn subject, will be fresh to most 

 readers. In speaking of the submergence of the so-called 

 Temple of Serapis at Puzzuoli, Dr.Roberts cites a passage 

 from the Acts of Peter and Paul, an apocryphal booklet, 

 to which attention was drawn a few months since by Mr. 

 Thomson {Geol. Mag., 1892, p. 282). This states that 

 Pontioli (Puteoli, now Puzzuoli) was submerged as a 

 punishment for the martyrdom of Dioscurus. " They all 

 see that city Pontioli sunk into the sea-shore about one 

 fathom, and there it is unto this day for a remembrance 

 under the sea." On which passage Dr. Roberts observes 

 that when the Acts was written, " Puzzuoli was under 

 water, and had been so for so long a time that the memory 

 of the actual events had been lost and replaced by the 

 tradition recorded in the Acts." At first sight this, as he 

 says, seems in favour of the submergence having occurred 

 NO. 1218, VOL. 47] 



" between the third and fifth centuries, and probably- 

 earlier than the fourth." 



This passage certainly makes it probable that the sub- 

 mergence began at a rather early time, but it is no easy 

 matter to fix the date of any passage in these Acts. 

 Parts of the book are believed to be as old as the second 

 century, while others are not earlier than the fifth century. 

 The book, also, was not of Western but of Eastern 

 origin. Had the book been written in Italy then, not- 

 withstanding its other absurdities, some weight might be 

 attached to a topographical reference ; but these, as it was 

 compiled at a distance, and by obviously ignorant people, 

 seriously impair its credit. It is also needful to show 

 that this story forms part of the later recensions and is not 

 merely founded on some vague tradition of change of level 

 in the neighbourhood. In any case. Dr. Roberts seems 

 to go a little too far in saying " this would allow about 

 ten centuries, during which the marble columns were 

 under water exposed to the action of the living molluscs.'' 

 Hardly so ; this tradition at most would not take us beyond 

 the first submergence, that indicated by the brackish 

 water deposit at the base of the pillars. Over this came 

 an irregular mass of volcanic ash, which was covered by 

 a calcareous tufa, in -places full four feet thick. The 

 former, of course, may have accumulated in a few hours, 

 but the latter must indicate a considerable time. The 

 temple, also, must have been in complete ruin before the 

 showers of ashes fell — which also would require time. So 

 that Dr. Roberts perhaps would have done better to have 

 adhered to the more cautious statement in Mr. Thomson's 

 letter, and not claimed quite so long a period for the 

 maximum submergence. 



Within the limits, which the necessities of the case 

 impose, the book is well conceived and well executed : 

 though we cannot help doubting the wisdom of encourag- 

 ing,by manuals necessarily partial and incomplete,students 

 to imagine that they have really mastered a subject ; at 

 any rate, it should be frankly admitted that this, however 

 useful and interesting, is not education. 



OUR BOOK SHELF. 



The Health Officer's Pocket-Book. By E. F. Willoughby, 

 M.D., D.P. H. (London: Crosby Lockwood and 

 Son, 1893.) 

 This is a work the object of which is to provide a port- 

 able and well-bound book of reference, to which the 

 health officer may turn at any moment for most of the 

 facts, formulae, and data required in his daily practice ; 

 and while one cannot give unqualified assent to Dr. Wil- 

 loughby's contention that such a book is indispensable, 

 one is prepared to acknowledge that it may prove to be 

 useful. It is not easy, however, to conceive the conditions 

 under which a health officer is called upon to take action 

 or to give advice, at a moment's notice, upon points so 

 remote from the routine practice of his duties that he will 

 ever find it necessary to carry about, for consultation, a 

 pocket-book of abstruse sanitary facts and formulas and 

 legal enactments. If such a work is indispensable, 

 the author would have done well to restrict its bulki- 

 ness somewhat, and more especially since he could 

 have achieved this by the omission of a great deal of 

 matter which is, on the face of it, foreign to the purpose 

 of the book. To instance such : — The parts which nitro- 

 genous and non-nitrogenous food stuffs play in the animal 

 economy ; the origin and nature of cyclones ; a quantity 



