NATURE 



\Nov, 14, 1878 



much experience. His zeal is contagious, and conse- 

 quently much of what he has written will favourably 

 attract the attention of the statist. 



It is a pity that the custom does not exist of weighing 

 and measuring all the members of a family at frequent 

 intervals between childhood to manhood, seeing how 

 critical a test of sanitary condition is afforded by the 

 progress of growth. Each illness leaves its mark, there- 

 fore a chart of height and weight with accompanying 

 remarks, would give in a compendious form a very 

 valuable life-history of the individual. 



A Text-book of Arithmetic for Use in Higher Class 

 Schools. By Thomas Muir, M.A., F.R.S.E. (Daldy, 

 Isbister and Co., 1878.) 



" Number," infers " Recorde," in his " Whetstone of 

 Witte," "is the onelie thing (almost) that seperateth 

 man from beastes. Hee therefore that shall contempne 

 numbre, he declareth himselfe as brutishe as a beaste, 

 and unworthy to be counted in the fellowshippe of men. 

 But I truste there is no man so foule ouerseene, though 

 manie right smallye do it regarde." — (De Morgan, 

 " English Mathematical and Astronomical Writers.") We 

 have done with the miserable mercantile compendiums 

 founded on Cocker, Avhich De Morgan condemned, and 

 have had, since his own "Arithmetic" appeared, many 

 works of high value. Mr. Muir's work is worthy of 

 taking place with these. His aims are high — mathe- 

 matical accurac}', rational treatment, the presentment of 

 essentials, with the accessories in due subordination, the 

 production of a work suited both for mental training and 

 as a preparation for the practical business of life. There 

 is perhaps matter given more suitable for the use of 

 teachers than of pupils — that is, for a school book we 

 think much might be more concisely put. Persons 

 taking up the subject at a more advanced age may find 

 this fulness of explanation very valuable. The exercises 

 are good and varied, and there is a chapter containing 

 notices of books for future reading. 



In connection with these notices and Mr. Muir's 

 chapter on the roots of numbers (a part of the work 

 which appears to us to require excision and^a new treat- 

 ment), we may add the following title : — "Elements de 

 Calcul Approximatif." Par Charles Ruchonnet (de Lau- 

 sanne). Seconde itdition. (Paris, 1874)— a work which 

 we have already noticed in Nature. 



The work is a thoroughly reliable one, accurately and 

 neatly printed. 



The Elements of Dynamics {Mechanics), with nutnerous 

 Examples and Examination Questiotts. By J. Blaikie, 

 M.A. (Edinburgh: J. Thin, 1878.) 



Mr. Blaikie says " special pains have been taken to 

 establish the necessary propositions by proofs involving 

 no higher mathematics than the geometry of the first two 

 books of Euclid, and algebra as far as simple equations. 

 At the same time the nomenclature, definitions, and 

 general treatment are in harmony with advanced modern 

 works on the subject." The author starts with kine- 

 matics and kinetics and derives statics as a particular 

 case. A chapter is devoted to machines and another to 

 hydrostatics. The objects laid down in the above state- 

 ment have been well kept before the writer s eye, and 

 the result is a good introductory book for young students. 

 A word of decided commendation is due to the selection 

 of general examples ; there are besides some six university 

 examination papers, specimens from the old universities, 

 and from Edinburgh, London and Glasgow. The list of 

 errata we have made is a very slight one, and we say this 

 after working out all the examples. 



This accuracy and carefulness of selection may be 

 attributed to the fact of the work having been examined 

 by such men as Professors Tait and Balfour Stewart and 

 Mr. N. M. Ferrers. That our favourable opinion of this 



work is not singular may be inferred from the fact that a 

 second edition is already in preparation. 



Handbook to Map of the Geographical Distribution oj 

 Animals. By Andrew Wilson, Ph.D., &c. (Edin- 

 burgh and London : W. and A. K. Johnston, 1878.) 



This is a very brief statement of the extent and limits 

 of the six zoological regions and sub-regions, as given in 

 Mr. Wallace's "Geographical Distribution of Animals," 

 with an enumeration of the chief groups of mammals 

 and birds characteristic of each region. The only novelty 

 is that of placing the Ethiopian region fourth in order, 

 thus separating it from the Palsearctic and Oriental, to 

 both of which it is closely allied, and making it follow 

 the Austrahan, with which it has no affinity. It is diffi- 

 cult to see the reason of this innovation, which will cer- 

 tainly not be considered an improvement. The map is 

 in two large sheets, with the regions and sub-regions 

 copied from Mr. Wallace's map,and similarlydistinguished 

 by colours. It is, however, a mere outline, and entirely 

 without names — a great deficiency in any case, and 

 especially when intended for junior students, to whom 

 alone such a meagre sketch of the subject would be 

 acceptable. 



LETTERS TO THE EDITOR 



[ 77ie Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, »r 

 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 othei'wise to ensure the appearance even of com' 

 munications containing interesting and novel facts. '[ 



Gigantic Land Tortoises 



My attention has been called to the recent discussions in 

 Nature (vol. xviii. p. 220 et seq.) in reference 10^:1116 geographical 

 distribution of the gigantic land-tortoises of Malta, the Gala- 

 pagos, and other oceanic islands (see also the annual address of 

 the president of the Geological Society). On my return to 

 America in 1864 from a four-years' residence in the guano key 

 of Sombrero, West Indies, I put a small collection of fossil 

 reptilian remains, found on that key, in the hands of the late 

 Prof. Jeffries Wyman, of Boston, who had kindly consented to 

 examine them. His report on the subject, received in August, 

 1865, was added as an appendix to a paper of mine on the 

 geology of the key, but the latter was partially injured by a fire 

 in the study of the late Prof. Joseph Henry, of the Smithsonian 

 Institution, and its publication consequently postponed. I have 

 since found time to restore and publish only a portion of my 

 own paper, ^ but the report of Prof. Wyman has remained un- 

 touched among the charred MSS. of my observations on the guano- 

 deposit of Sombrero. I inclose herewith a copy of Prof, Wyman's 

 report, and also his subsequent autograph letter, in returning me 

 the specimens. (In the former I have supplied, in italics, the 

 probable words which are missing along the singed edges of 

 some of the leaves.) I have thought these details worthy of 

 statement in justice to this distinguished comparative anatomist 

 — who recognised thirteen years ago the occurrence of this in- 

 teresting fauna in a locality of the Atlantic, and one evidently 

 unknown to the recent investigators — and in explanation of the 

 long delay in the publication of his views. The specimens in 

 question remain still in my possession, with the exception of one 

 in the museum of this school. 



I may further state that fossil specimens of these turtles, 

 mostly fragmentary, have been found in many of the northern 

 excavations upon Sombrero, since they were first worked, in 

 1856, and perhaps are still, as its exploitation has been con- 

 tinued by an English company for many years past. They occur 

 altogether in the guano-veins which intersect the limestone beds 

 to an unknown depth beneath the sea-level, and which are cer- 

 tainly but insertions from an ancient surface-bed of rock-guano, 

 overlying but long since entirely denuded along with the crown 

 of the key. In 1860-61, just before my arrival, enormous 

 quantities of a guano -breccia were taken out from the largest of 

 ' "Ann. Lye. of Nat. Hist, of N.Y.," 1868, p. 231. 



