June 17, 1897] 



NATURE 



»5i 



passage from the westernmost, rocky island of Savaii 

 eastward, past reefs of diminishing size, to the last 

 member of the group, the small Rose Atoll. Beyond 

 that island there are some 900 miles of open sea, until 

 the small atolls of the Society Islands begin another 

 series leading up to the great Paumotu Archipelago. 

 Dana explained the distribution of the reefs by assuming 

 that the line between Rose Atoll and the Paumotus had 

 rapidly subsided. This suggestion was in harmony 

 with all the known facts. It has been the argument 

 least shaken during the discussion on Dr. Murray's 

 tlieory, and has accordingly kept some men firm in the 

 Darwinian faith. Funafuti was originally recommended 

 by the original Coral Island Boring Committee as a 

 -uitable site forja bore-hole, after it had been tested by 

 this principle in order to minimise the chance of stumbling 

 on an area of rising sea-floor. 



Now, however. Dr. Kramer, in a detailed description 

 of the Samoan reefs, shows that the facts are not exactly 

 as stated, and that another explanation is available. 

 Dr. Kramer's^book opens with a sketch of the literature 

 on the coral reef controversy, which is neither complete 

 nor altogether accurate ; for he numbers Admiral 

 Wharton among the defenders of Darwin's theory, and 

 Prof. SoUas among its opponents. He then gives an 

 account of the topography, meteorology and geology of 

 the Samoan group, after which follows a detailed descrip- 

 tion of the coral reefs. The next section of the book 

 discusses the conditions which determine the limits of 

 coral-reef formation, and in which the most original re- 

 marks are those dealing with the influence of heliotropism. 

 (His observations on heliotropism in corals have, by the 

 by, an important bearing on the question of the validity 

 of coral species founded on the nature of the corallum.) 

 He concludes his contribution to the reef controversy by 

 a chapter entitled " a new view of the origin of atolls." Dr. 

 Kramer points^out, during his description of the Samoan 

 reefs, that they are not disposed exactly as they should 

 be to agree with Dana's suggestion, that the eastern end 

 of the archipelago is undergoing rapid subsidence. The 

 reefs are not as regularly arranged as has been thought. 

 Proceeding from west to east, Savaii has no very extensive 

 reefs except on the east coast ; Upolu, the next island, 

 has large fringing reefs at the west end, fringing and 

 small barrier reefs in the middle section, and un- 

 important fringing reefs at the east end ; Tutuila has 

 only a fringing reef on the southern shore, and two 

 submarine barrier reefs further out ; Manua has no 

 important reefs ; finally, the easternmost island of the 

 chain is Rose Atoll. These facts appear conclusive that 

 the Dana>argument will not hold for its typical locality. 



Kramer then proceeds to discuss the origin of the 

 remarkable shapes of atolls, which Darwin thought it 

 was impossible to explain on the view that atolls formed 

 either on the rims of volcanic craters or on submerged 

 banks. Kramer invokes the aid of great geyser eruptions, 

 in order to widen the bases and alter the forms of sub- 

 marine volcanoes. He poitits out that the distribution 

 of volcanic ejectamenta depends not only on its specific 

 gravity, for ocean currents and tides carry the material and 

 pile it up in the dead water to the lee of volcanic islands. 

 He reproduces a chart from Dana, showing how the trend 

 of the coral archipelagoes agrees with that of the ocean 

 NO. 1442, VOL. 5b] 



currents in their neighbourhood ; and he supports this 

 by similar charts of the Paumutu and Marshall Islands. 

 The difficulty of deep lagoons he explains by assuming 

 that atolls with such, originated on crater rims ; and he 

 is more inclined to Murray's solution theory than are 

 most writers on coral islands, although he remarks that 

 it does not seem sufficient by itself. 



The concluding section of Dr. Kramer's book deals 

 with some biological problems of the Pacific Ocean. A 

 few pages are devoted to the reef fauna, considered in 

 reference to its ethnological relations, and then follows a 

 longer account of the Plankton. The author describes 

 his apparatus and methods at some length. The most 

 interesting result given in this section of the book are 

 his statistics of the comparative poverty of the tropical 

 Plankton compared with that of the temperate zones. In 

 an appendix on the Palolo, a worm largely eaten by the 

 Samoans, Tonguese and Fijians, Dr. Collin re-describes 

 its structure from excellent material collected by Dr. 

 Kramer. He agrees with Quatrefages and Ehlers that it 

 is a member of the genus Lysidice, and that Gray's 

 genus, Palola, must be given up. J. W. G. 



OUR BOOK SHELF. 

 A Treatise on Practical Plane and Solid Geometry. 

 By T. J. Evans and W. W. F. PuUen. Pp. vi -f- 400. 

 (London : Chapman and Hall, Ltd., 1897.) 



In these 400 pages the joint authors present the student, 

 particularly the one who wishes to restrict his work to the 

 Science and Art Department syllabus of the honours 

 stage of the annual examination held in geometry, with 

 the solutions of a series of problems arranged in an 

 orderly and progressive manner. The problems are, for 

 the most part, those which have been set at the ex- 

 aminations held during the years 1887 to 1896, and 

 their solutions are accompanied, in many cases, by useful 

 hints. There are also included the theories of isometric 

 projection, shadows, and perspective, and several inter- 

 esting miscellaneous examples, besides some of the less 

 difficult problems which are of fundamental importance. 

 It is not advisable for a student to limit himself entirely 

 to the reading of such a book as this, but using it in 

 connection with a good text-book its value will be very 

 much enhanced : for this reason, the authors have made 

 ample references to existing standard works. No less 

 important are the excellent and clearly printed figures, 

 to the number of 200, which accompany the text ; these 

 should be well studied, and, in most cases, re-drawn by 

 the reader himself. For advanced students and teachers 

 this collection of problems and proofs will, without doubt, 

 prove a most useful help in their work. 



Les Transformateurs de tension a courants alternatifs. 



By F. Loppe. Pp. 206. (Paris: Gauthier-Villars. 



Masson and Co.) 

 Alectromoteurs et leurs Applications. By G. Dumont. 



Pp. 183. (Same publishers.) 

 Alectro-mt'tallurgie. By A. Minet. Pp. 195. (Same 



publishers.) 

 These books are the three latest additions to the well- 

 known series published under the title of the Encyclopddie 

 scientifique des Aide-Mt^moire. All the volumes in the 

 series have proved handy and serviceable to students of 

 science and technology. 



The first part of M. Lopp^'s work deals briefly with 

 the theory of the transformer, and ideal conditions 

 of construction ; the second part is devoted to the classi- 

 fication of transformers, details of construction, the 



