Nov. 1 8, 1880] 



NATURE 



53 



trations accompany the description ; some of ttiese are 

 original, and others taken from the French, and none the 

 worse for that. Most of them are well executed, but 

 intimate friends might possibly find some fault with the 

 likenesses of living men of science. Of course it is an 

 easy as it would be a thankless task to point out sins of 

 omission, and perhaps also of commission, in a book like 

 the one under notice. Such works must not be looked 

 upon with the eye of microscopic criticism. If the general 

 direction which the author takes is the right one, if he 

 does not make his task easy by glossing over all the 

 points of difficulty, but puts his case clearly and fairly 

 forward, he may well be excused if he omits matters 

 which one or other of his readers may deem necessary. 

 These conditions iVIr. Routledge, as it seems to us, has 

 satisfactorily fulfilled. We can therefore cordially re- 

 commend this "Popular History of Science," believing 

 that it will exert a healthy influence on all who read it, 

 and may be a powerful means of spreading the love of 

 science amongst the rising generation. H. E. R. 



Class-Book of Ekinentaiy Mechanics, adapted to the 

 Requh-cments of the Neiu Code. Part I. Matter. By 

 \Vm. Hewitt, B.Sc, Science Demonstrator for the 

 Liverpool School Board. (London : George Philip and 

 Son, 18S0.) 

 Mr. Hewitt has probably had a better chance than any 

 other teacher of knowing by experience the working of 

 the meagre science-subjects of the new educational code. 

 The defects of that code, and particularly of its directions 

 as to the subject of mechanics, are very great ; neverthe- 

 less the little book which Mr. Hewitt has produced shows 

 how, in spite of the disadvantageous system under which 

 he works, a really good teacher will succeed in working 

 up the subject for his pupils. We have seldom met with 

 a realty elementary book which at once combined to so 

 great a degree simplicity of language, accuracy of descrip- 

 tion, and sound science. Mr. Hewitt states as his 

 experience that the main difficulty has hitherto been to 

 get the children to express in anything like precise 

 language the ideas suggested to their minds by the simple 

 experiments shown them. He therefore intended this 

 little work to serve as a lesson-book to be read by the 

 pupils in the intervals between the experimental lessons. 

 This first part covers the ground prescribed by Schedule 

 IV. for the first stage. A second part, dealing with 

 " Force," is in preparation, and will embrace the subjects 

 of the second and third stages. We hope Mr. Hewitt's 

 second part will prove as satisfactory as is his first instal- 

 ment. His aims are limited, indeed, by the requirements 

 of the Code, but within those narrow limits his success is 

 great. 



LETTERS TO THE EDITOR 



[The Editor does not hold himself rcsfonsihls 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 anonymons 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 ensure the appearance even of com- 

 munications containing interesting and novel facts.^ 



Sir Wyville Thomson and Natural Selection 



I HAVE at least great reason to be thankful that my stupidity 

 has not prevented me from thoroughly enjoying the teachings of 

 Mr. Darwin and Mr. Wallace, which I confess to having 

 regarded as chiefly masterly and charming "studies in varia- 

 tion," for the last twenty years. 



The title of the epoch-marking book which came of age last 

 month was, however, " The Origin of Species by Means of 

 Natural Selection." Mr. Darwin, as I am well aware, has put 

 forward this mode of the origin of species as a part only of a 

 hypothesis which is universally looked upon as a supreme effort 

 of genius. 



It seemed to me, riyhtly or wnnigly, that the fauna of the 

 enormous area formincr the abyssal region exi ted under condi- 

 tions which held out "the hope that it might throw S'.me light 

 upon a question which appears to underlie the whole matter, 

 and w hich is still unansw ered. Are physiological species the 

 result of the gradual modificalion of pre-exisiing species by 

 natural selection, or by any similar process ; or are they due 

 to the action of a law as yet utterly unknown, by which the 

 long chain of organisms rolls off in a series of definite links ? 



I fear I scarcely follow Mr. Darwin's illustration. If one 

 were to pay his first visit to a breeder's, and be shown a flock of 

 Lexesters, never having seen or heard of a sheep before, he 

 would see nothing but a flock of sheep, and would cert;iinly, 

 without justly incurring the contumely of the lireeder, be entuled 

 to set them down merely as a group of animals of the same 

 species, that is to say, animals fertile \\ith one another and pro- 

 ducing fertile progeny. He would judge so frcm their common 

 resemblance, and without previous observation or information 1 do 

 not see how he could know more about them. But give him an 

 oppurtunity of comparing the results of breeding throughout a 

 long period of time, or of observintj the process of breeding over 

 half the world, which comes to much the same thing ; the hreeder 

 might then have cause to rail if he had not picked up the stages 

 of the process. 



The close examination of the newer tertiaries and the careful 

 analysis of the fauna of the deep sea seem to me fairly to repre- 

 sent these two methods ; both of these promise to yield a ma-s of 

 information in regard to the course of evolution, but as to the 

 7?todc of the origin of species both seem as yet equally silent. 



I will ask you in a week or two for space for a short paper on 

 " The Abyssal Fauna in Relation to the Origin of Species." 

 C. Wyville Thomson 



Rapidity of Growth in Corals 



Thkough the kindness of M. Parrayon, captain of the French 

 man-of-war Da-\ot, I have received a large coral of the fungia 

 tribe, which was yesterday found attached to the bottom of his 

 ship as the copper was being cleaned by native divers. The 

 following is the history of the occurrence. The Dayot entered 

 the tropical waters of the South Pai:ific about seven months ago, 

 comiu'^; directly from the coast of Chile. She visited some of 

 the islands, but made no long stay in harbour until she reached 

 Mauga Keva (Gambia Islands), where she remairied for two 

 months in the still waters of a coral ba-in. On entering the 

 basin she touched the reef slightly, and without sustaining any 

 damage. From Manga Reva she sailed to Tahiti, where she now 

 lies. 



Several specimens of living coral were found attached to the 

 copper sheathing, that which X have received being the lari;est. 

 It is di-coidal in shape, with its upper and under surfaces 

 respec'ively convex and concave, and near the centre of the 

 under surface there is a scar, where the pedicle by which it was 

 attached to the copper sheathing was broken through. The 

 disk measures 9 inches in diameter, and the weight of the speci- 

 men (now half dry) is 2 lb. 14 oz. On examining the under 

 surface another disk 3* inches in diameter is seen partly im- 

 bedded in the more recent coral growth. Of this ol 1 disk about 

 one-sixth part is dead and uncovered by new coral, nd is stained 

 of a deep blue colour from contact with the copper, while the 

 outline of the rest of this old disk is plainly discernible, although 

 partially covered in by plates of new coral. 



My impression is that on touching the reef at Mauga Reva nine 

 weeks ago a young fungia was jammed against the copper, 

 became attached, and subsequently grew to its present dimen- 

 sions. 



The case affords an interesting illustration of the rapidity of 

 the grow th of coral in these waters. R. W. Coppinger 



Tahiti, August 13 



Geological Climates 



Since contributing the chapter in the history of the Coniferje 

 upon which Prof. Ifaughton remark-, 1 have seen Araiicaria 

 Cunninghami growing in gardens round Funchal, and my belief 

 in the specific identity of the Bournemouth Eocene plant is 

 further strengthened ; yet still, as only foliage is known in the 

 fossil, I should hardly be prepared to contest upon that aione a 

 question of climate, however minute the resemblance. But even 

 with the most undisputed identity there are so many possibilities 



