Feb. 4, 1886] 



NA TURE 



■h^^l 



the experimental value of the last three or four 

 rigures ? The specific gravity of each species relative 

 to water is given as usual, so that the reference to 

 hydrogen is only an additional torment for the learner. 

 We doubt too the wisdom of explaining specific and 

 atomic heats, and giving lists of their values. Iso- 

 morphism and pseudomorphism are hopelessly con- 

 fused and interchanged on p. 20, while the illustrative 

 formula is quite unintelligible. The adjusting apparatus 

 of the ungraduated goniometer is, as usual in text-books, 

 wrongly disposed for use. We have noticed several 

 mistakes of fact and errors of printing ; but the book 

 is neat in style, and perhaps will not do much harm. 



The Prospect fl)-'s Handbook. By J. W. Anderson, M.A., 



F.R.G.S. 8vo, pp. 132. (London : Crosby Lockwood 



and Co., 18S6.) 

 The author, after traversing the mineral fields of New 

 Zealand, New Caledonia, New Mexico, and Colorado, 

 feels convinced that some simple guide or handbook for 

 the use of prospectors as well as travellers is a desidera- 

 tum, and the present volume is the outcome of this 

 conviction. It contains a number of notes or para- 

 graphs upon subjects incidental to metallic mining, 

 which are distributed into chapters under the different 

 heads of prospecting, rocks, blowpipe-testing, character 

 of minerals, metals, and metallic ores, other useful 

 minerals and ores, composition of various rocks, testing by 

 the wet process, assay of ores, and surveying ; to which are 

 added an appendix of tables and a glossary of terms. .As 

 the whole text is contained in rather more than a hundred 

 pages, not very closely printed, it will be easily under- 

 stood that no one of the numerous subjects included in 

 the author's programme is very thoroughly treated. The 

 best part of the book is the introductory chapter on 

 prospecting, which contains some useful generalisations 

 on mineral deposits and the search for them, Avhich, how- 

 ever, are more likely to be of use to the " tender-foot '' 

 than to the prospector properly so called. It would seem, 

 however, that this is what the author has in contempla- 

 tion, as, from some remarks on p. 9, he appears to con- 

 sider prospectors and miners as two different classes of 

 men, and evidently has no very favourable opinion of the 

 latter. Our own experience points in the opposite direc- 

 tion and leads us to regard typical prospectors as repre- 

 senting the highest and most intelligent class of operative 

 miners. Unfortunately it is difficult to keep them on 

 regular mining works except during the winter time, 

 when the mountain regions are inaccessible. 



The remainder of the book is of very little value. The 

 descriptions of minerals are short, without being clear, 

 and in many cases far from accurate. Thus, the compo- 

 sition of galena is stated to be " 80 per cent, of lead, the 

 rest sulphur" ; malachite is said to contain 70 per cent, 

 of copper, and silicate of zinc about 67 per cent, of zinc. 

 All of these statements are incorrect, and it is not easy 

 to see why they have been made, as no more space would 

 have been required to give the composition corresponding 

 to the theoretical constitution. 



The sections on assaying and analysis are not likely 

 to be required by the prospector in the field, and are too 

 vague to be of much use to sedentary students. A de- 

 scription of the methods adopted in sampling gold and 

 silver-bearing vein-stuff in the Western .States and Terri- 

 tories of America would have been of interest, but we 

 find no notice of this or any analogous practice followed 

 elsewhere. 



The glossary at the end contains several curious defini- 

 tions, many of which, however, are reproduced from pre- 

 viously published works. The description of the term 

 " tribute " more properly applies to dues or royalty rents 

 as understood in this country. It may be that the author's 

 definition applies to some local foreign usage, but this is 

 not stated. H. B. 



LETTERS TO THE EDITOR 



[ The Editordoes not hold himself responsil)lef or opinions expressid 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the writers of, rejected manuscripts. 

 No notice is taken 0/ 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 insure the appearance even 

 of communications containingintercsting and novel facts. ^ 

 Hereditary Stature 

 Permit me to correct one word in my memoir on ** Hereditary 

 Stature " in the last number of Nature (p. 297, col. i, line 6 

 from bottom), which should read *' seven "on an average. I 

 should be glad at the same time to amplify the passage in which 

 it occurs, as follows ; — 



The chance that the stature of the son will at least rival the 

 stature of the father, is not uniform ; it varies with the height of 

 the father. When he is of mediocre stature, that is, 5 feet 81 

 inches, out of every 100 sons born to a group of fathers of that 

 height, 50 will be taller and 50will be shorter than their fathers (the 

 practically impossible case of absolute equality being neglected). 

 Here then the chance of which we are speaking = <,o per cent. 

 When the father is tall, the chance in question diminishes ; 

 when he is very tall, say 6 feet 5 inches, the chance is reduced 

 to seven per thousand. The following table shows the proba- 

 bilities in various cases. Columns A contain the height of the 

 fathers, Columns B show how many per cent, of the sons will 

 rival or surpass the height of their fathers : — 



07 

 03 



Francis Galton 



Deposits of the Nile Delta 



Two" communications from Sir William Dawson, published 

 in N.\TUKE of January 7 and 2S (pp. 221, 298), appear to call 

 for a short notice from me. The report on the above sub- 

 ject which I read before the Royal Society on November ig, 

 1885, and of which an abstract appeared in NATURE of 

 December 10, ought not to be referred to as " the report of the 

 Delta Committee of the Royal Society." The origin of this 

 report was as follows : — As there was no other geological 

 laboratory available for the examination of the samples of delta- 

 deposits sent home by Col. Maitl.and than the one connected 

 with the Normal School of Science and Royal School of Mines, 

 the other members of the Delta Committee requested me to 

 undertake the microscopical and chemical investigation of the 

 specimens. In preparing my report on them I was struck by 

 the remarkable and unexpected characters which they presented, 

 and I ventured to suggest a mode of accounting for them. When 

 my report was submitted to the Committee I was requested to lay 

 it before the Society ; and, it w ould seem quite superfluous to 

 add, neither the Committee nor the Society thereby accepted 

 any responsibility for the views which I expressed in the report. 



As Sir WilHam Dawson lies under a manifest disadvantage in 

 attempting to criticise a report which he has not seen, it will 

 not be necessary to enter at length upon the subject of his com- 

 munications. If I understand the first of these aright, he takes 

 the opportunity in it of withdrawing his untenable assertion that 

 "at a depth of 30 or 40 feet the alluvial mud rests on desert 

 sand " in favour of the totally different statement that " the 

 modern Nile mud " lies on " a Pleistocene or Isthmi.an deposit. " 

 In the .absence of any pal:eontological evidence I can offer no 

 opinion as to the truth of this latter view ; but it is certain that 

 the deposits above and below the limit mentioned are of pre- 

 cisely similar mineral characters. With respect to the second com- 

 munication, I need only add that when its author has the 

 opportunity of reading the report in question, he will find that 

 the very obvious considerations to which he refers have been by 

 no means lo?t sight of John W. Judd 



Stone Implements and Changes of Level in the Nile 



Basin 

 I INCLOSE a letter from my brother at Wady Haifa. The 

 scrapers sent home are all made out of flat oval pebbles of 



