May 3, 1888] 



NATURE 



a handy and cheap form, as well as to discuss some 

 simple examples of their application. 



The first part — which gives an explanation of graphical 

 methods, illustrates graphical arithmetic, and shows how 

 to represent areas and volumes by lines — is very carefully 

 and clearly worked out, and leads one to see that this 

 part of the subject might well come in at a fairly early 

 date in school-work. Our idea is that the second part, 

 " Graphical Statics," would be improved by more fullness 

 of detail. It comprises an account of the following 

 matters : kinematics, forces in one plane acting at 

 a point, the funicular polygon, resolution of forces, 

 moments, couples, bending moment and shearing force 

 in a simple beam, rolling loads, framed structures, effects 

 of wind-pressure on roofs, bridge-girders, and centres of 

 gravity. 



We have noted only two or three typographical errors. 

 The notation employed is one most frequently termed 

 " Bow's notation " in this book, from its having " been 

 brought into use by Robert H. Bow, Esq., C.E.," but a 

 note states that "the method seems, however, to have 

 been first suggested by Prof. Henrici." We presume that 

 Prof. Henrici's notation was the one we have referred to 

 in the opening paragraphs of this notice. The immediate 

 object of the book is to furnish help to students preparing 

 for the South Kensington Examinations and for those of 

 the City and Guilds of London Institute. 



The Manual Training School. By C. M. Woodward. 

 (Boston : D. C. Heath and Co., 1887.) 



Mr. Woodward has by no means a high opinion of the 

 results of the efforts that have hitherto been made in 

 European countries to promote technical education. In 

 1885 he spent five months in examining " trade schools " 

 on this side of the Atlantic, and all the schools visited by 

 him, with the exception of the French Government 

 school at Chalons, disappointed him. He admits that 

 they have "many excellent features " ; but their manual 

 training is generally, he holds, " very narrow," and he 

 condemns " their long daily sessions, their long terms, 

 and the conventional nature of their curricula." Manual 

 training, according to Mr. Woodward, is in a much more 

 flourishing condition in America. There it has been 

 introduced " not for a trade or a profession, but for the 

 healthy growth and vigour of all the faculties, for general 

 robustness of life and character"; and he is of opinion 

 that it has been developed in a way that places it " far in 

 advance of any model in a foreign land/' Whether or 

 not this comparative estimate is accurate, no one who 

 reads Mr. Woodward's book will dispute that the 

 Americans have begun to understand thoroughly the 

 importance of technical instruction, and that the leaders 

 of opinion on the subject have done much to diffuse 

 enlightened ideas as to the true aims and methods of 

 manual training. Unfortunately, Mr. Woodward has not 

 the art of presenting facts and arguments in an attractive 

 style. He has, however, brought together a great mass 

 of useful information about a subject of pressing import- 

 ance, and his work, although relating chiefly to institu- 

 tions founded in his own country, ought to find readers in 

 England as well as in the United States. He does not 

 enter, in detail, into the theory and practice of manual 

 training in primary and grammar schools. He limits 

 himself to the training of pupils beyond the age of 

 fourteen. The value of the work is increased by a 

 number of good woodcuts illustrating shop exercises 

 in woods and metals. 



The Method of Creation. By Henry W. Crosskey. 

 (London : The Sunday School Association, 1888.) 



This little volume belongs to a series of " Biblical 

 Manuals," edited by Prof. J. Estlin Carpenter. With the 

 polemical parts of the book we have, of course, nothing 



to do. In the chapters in which Mr. Crosskey devotes 

 himself simply to the exposition of scientific truths he 

 writes with full knowledge of his subject and in a clear 

 and pleasant style. " How ' dry land ' was formed" is the 

 subject of an excellent chapter, in which the writer brings 

 together some of the more striking of the facts which 

 prove that rocks have been formed by various agencies, 

 that there is no single period at which any kind of rock 

 has been specially produced, that the crust of the earth 

 consists of rocks in ordered succession, and that there has 

 been an unvarying order in the succession of rocks. 

 There are also good chapters on the history of plants and 

 animals, and on the antiquity of the human race. 



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. .] 



" Coral Formations." 



Dr. Guppy's letter shows that I have not been sufficiently 

 explicit on the subject of the formation of atolls, yet I cannot 

 well understand that I have been obscure on the subject of his 

 first question. Surely it is a sufficient reason for rejecting the 

 theory of subsidence as applied to the Chagos Group that I 

 fancy myself, in conjunction with M. Spurs, to have detected 

 evidences of elevation in Diego Garcia. Darwin laid great 

 stress on the character of the Great Chagos Bank as affording 

 evidence of his theory of subsidence ; he considers it to be an atoll 

 drowned by a too rapid act of subsidence ; but, as I have pointed 

 out, if this were so it is impossible to understand how two atolls 

 such as the Great Chagos Bank and Centurion's Bank could have 

 been thus destroyed without Six Islands or Egmont's Atoll, which 

 lies directly between them, being involved in their destruction. 

 Further, the raised atolls north of Madagascar are unquestion- 

 able proofs of upheaval in this region, yet in the same region are 

 low-lying atolls, atoll-shaped reefs awash, and submerged atoll- 

 shaped banks. Clearly the theory of subsidence does not apply 

 to these groups, and I do not see any reason for supposing that 

 the Laccadive and Maldive Islands have been formed differently 

 to the other atolls in the Indian Ocean, though I am unable to 

 bring forward any fresh arguments with regard to them. 



Secondly, because I do not agree with Mr. Murray in thinking 

 that lagoons are due largely to the solvent action of sea-water, 

 it is no reason that I should disagree with other parts of his 

 theory. Indeed, after Dr. Guppy's striking observations at 

 Santa Anna and other islands, it would be idle to deny that 

 organic deposits have formed the bases of many atolls, perhaps 

 of all. It did not seem to me necessary to deal with this part of 

 the subject, because as a resident on an atoll without the means 

 of making sectional soundings I had nothing new to say on the 

 subject. 



Perhaps you will allow me space to add that before reading 

 my paper I had not had the advantage of meeting Mr. Murray. 

 I have since had that advantage, and on comparing notes with 

 him I find that I am much more in accord with him than my 

 paper would seem to show. I still maintain my point that the 

 rate of organic growth in the lagoon of Diego Garcia is suffi- 

 cient to counterbalance the solvent action of the sea-water. In 

 other points I agree with him, and believe that my observa- 

 tions confirm his view that atolls tend to spread outwards like a 

 fairy-ring. Mr. Murray has convinced me that I laid undue 

 stress on the direct influence of currents in determining the 

 growth of corals, and this section of my paper was in con- 

 sequence omitted in the account which appeared in the columns 

 of Nature. Judging from the local effects which I observed at 

 Diego Garcia, where currents often swept through narrow chan- 

 nels with great force, and from Prof. Moseley's account of the 

 oceanic currents sweeping past St. Paul's rocks, I was led to an 

 exaggerated estimate of the rate of oceanic currents. No doubt 

 a current running at the rate of some thirty-five miles in the 

 day would modify or retard coral growth, but such currents are 

 only found in narrow passages. G. C. Bourne. 



