Jan. 31, 1889] 



NATURE 



317 



sewage works, that they may know what tricks may be 

 .ittempted. It is commonly said 'that any stick is good 

 enough to beat a dog with,' and on a similar principle, any 

 unfair, dishonourable stratagem is held legitimate to 

 bring discredit on a process for the chemical treatment 

 of sewage." " Another necessary precaution relates to 

 sampling. If any visitor asks for a sample, it should be 

 given him solely on the condition that he takes and seals 

 up at the same time a check sample, to be left at the 

 works for analysis by some independent chemist. With- 

 out this precaution he may, for instance, add to his 

 sample a little urine or blood, or a culture solution, and 

 still represent it as a normal sample" (p. 170). These 

 passages serve to show the opinion in which the author 

 holds his brother experts. 



It is very plain that the author rejects in toto all ex- 

 perience but what is favourable to his own views. The 

 following passage is a specimen of the assertions con- 

 stantly made throughout the book :— " Just in proportion 

 as a sewage is purified by precipitation, its manurial value 

 for irrigation will decrease down to that of plain water " 

 (p. 70). This statement, which implies that complete 

 purification is attainable by precipitation processes, is at 

 total variance with the truth, and has been disproved 

 over and over again ; but it is a sufficient index of the 

 kind of treatment the subject throughout receives. 



On the subject of sewage manures the author quotes, 

 as representative of their average composition and value, 

 the results of Dr. Tidy's analysis of the sewage manure 

 from the "A. B.C." process at Aylesbury. Can the author 

 not be aware that the Aylesbury manure has become one 

 of the wonders of the scientific world ? How is it that 

 the " A.B.C." process can convert a nearly worthless sub- 

 stance — sewage sludge— into a rich and paying manure? 

 Can the author tell us ? 



OUR BOOK SHELF. 



The International Annual of Anthony's Photographic 

 Bulletin. Edited by W. Jerome Harrison, F.G.S., and 

 A. H. Elliot, Ph.D. (London: E. and H. T. Anthony 

 and Co., 1888.) 



In the pages of this volume we have a valuable collection 

 of articles written by men many of whom are eminent 

 in the art and science of photography. 



At the present day, considering the great number 

 working, either as amateurs or professionals, at this 

 subject, and that that number is still on the increase, 

 and also the numerous books that have been pub- 

 lished, one would think it hard for another work to differ 

 a great deal from those preceding it. The editors, in 

 their preface, tell their readers to " partake of and enjoy 

 tlie feast that they have set before them ; and, if the 

 viands tickle their palates, praise rather the maker of that 

 particular dish than those who have spread the table." 



The present work consists of a popular account of 

 nearly every branch of the subject, including stellar 

 photography. 



The volume is beautifully illustrated by specimens of 

 various methods of printing, engraving, &c. The appendix 

 contains a list of Photographic Societies of the British 

 Isles, colonies, and of America, with numerous tables. 



The editors have produced a volume which will not 

 only be appreciated by members of the photographic 

 world, but will be interesting to any ordinary reader. 



Instruction in Photography. By Captain W. de W. 

 Abney, C.B., R.E., F.R.S. Eighth Edition. (London : 

 Piper and Carter, 1888.) 



All that is needed for photographers, whether amateur 

 or professional, will be found in this well-known book, 

 which has been thoroughly revised and brought up to 

 date. By the addition of new matter the volume has 

 been slightly increased, and an alteration of some import- 

 ance consists in the introduction of both the French 

 and English measures for the various formulas used 

 throughout. 



The work is profusely illustrated, and the least we can 

 say is that no studio ought to be without it. 



Lessons in Elementary Physics. By Balfour Stewart, 

 M.A., LL.D., F.R.S. New and Enlarged Edition. 

 (London : Macmillan and Co., 1888.) 



The present edition of this well-known book was prepared 

 only in part by the late author. The task has been com- 

 pleted by Mr. W. W. Haldane Gee, B.Sc, Lecturer of the 

 Victoria University. No material alterations have been 

 made, except in the chapters relating to electricity and 

 magnetism, which have been rearranged, and expanded 

 by the addition of new matter and figures. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he under- 

 take to return, or to correspond with the writers of, 

 rejected manuscripts intended for this or any other part 

 of Nature. No notice is taken of anonymous communi- 

 cations. ^ 



Supposed Fossils from the Southern Highlands. 



In the article in your last number upon my paper lately read 

 before the Royal Society of Edinburgh, respecting the discovery 

 of some supposed annelid tubes in the quartzites of Loch Fyne, 

 some observations are made on the interest attaching to the 

 question as bearing on the geological horizon of the metamorphic 

 series which constitute the great bulk of the South- Western and 

 Central Highlands. With reference to this question, however, 

 I am anxious to discl.aim attaching any great importance to the 

 discovery of annelids, because I do not admit that any real 

 doubt exists as to the Silurian horizon to which our rocks were 

 referred by Murchison. In this country, particularly, the 

 evidence seems to lue complete whether fossils be, or be not, 

 found in them ; because in tliis country we have complete 

 stratigraphical evidence from the occurrence of a small local 

 coal-basin in the district of Kintyre. The backbone of that 

 long peninsula consists of the same metamorphic rocks as the 

 rest of the country. Along its shores it is fringed by cakes of 

 Old Red Sandstones which have resisted denudation, or have 

 survived destructive dislocations. At the southern end of 

 the peninsula these sandstones have survived in consider- 

 able masses — including beds of conglomerate, of freestone, 

 and of limestones. All these beds rest unconformably 

 on the metamorphic schists and limestones, whilst they are, 

 again, also to be seen dipping and passing under the coal- 

 measures and Carboniferous limestones in their usual and natural 

 order. There can be no doubt of the order of succession in 

 this case, and it establishes the position of our metamorphosed 

 slates and quartzites as rocks which belong to the horizon 

 below the Old Red. 



Of course, the discovery of fossils would put an end to the 

 new surmise that they are not sedimentary deposits at all, but 

 intrusive rocks, simulating true bedding in consequence of 

 "foliation," or some other process of mineralization. But 

 this surmise is so wild that I feel no doubt about its early 

 disappearance. 



In this, I believe Dr. Geikie entirely agrees ; and he has con- 

 sequently expressed a confident expectation that fossils will be 

 found in our schists and quartzites some day. 



I may add that since my return from Edinburgh a correspon- 



