July 25, 1907J 



NA TURE 



30.^ 



Board on " The Distribution and Seasonal Abundance of 

 the Flat-fishes in the North Sea," by Dr. Fulton. This 

 IS also largely a statistical paper, and somewhat overlaps 

 Henking's work in the North Sea and the Cattegat, and 

 Dr. Heincke's, so far as flat-fishes are concerned. .\ main 

 point is the " complementary and compensatory fluctu- 

 ations " in the statistics, e.g. the " witch " or pole-dab in 

 square xiv., near the Fair Isle, taking, during the winter, 

 the place of dabs, lemon dabs, and plaice. Uncertainty, 

 however, e.xists, as no other method of fishing than trawling 

 was used on the same ground to make sure the other forms 

 were not there. This condition is well known to fisher- 

 men. In regard to the maximum of the captures in each 

 fish, it is found that it corresponds to the spawning 

 season. While this paper likewise does not deal directly 

 with the great question handed over to the ScotcTi Board 

 to solve, it indirectly supports the " Resources of the Sea " 

 in so far as the total average of lbs. per hour of fishing 

 was greater (in flat-fishes) in 1903 than in 1901. 



One of the most important papers is that of Dr. H. M. 

 Kyle, who shows that the quantity of fish of all kinds 

 landed in the North Sea ports, and especially of flat-fishes, 

 was greater in 1903 than in 1902. This is clearly sub- 

 stantiated by Johanscn's observations on Danish plaice. 

 Hjort's work, again, removes any fear of diminution of 

 round fishes for the supply of the North Sea. 



While, therefore, the work of the British international 

 observers up to date does not show an answer to the 

 fundamental question submitted by the Government, yet 

 it inadvertently supports the " Resources of the Sea," and 

 is fairly compatible with the safety of the fishes in the 

 North Sea. Finally, a separate English Fisheries Board, 

 as Lord Dalhousie recommended, was suggested. 



.V£TF ZE.4L.4.VD PETROGR.iPHV.' 

 "T^HE first volume of this work was reviewed in Nature 

 of January 4, 1900, vol. Ixxiii., pp. 234, 235. We 

 noticed in that place the reasons which led to these Cape 

 Colville rocks being selected for special study, and also 

 the circumstances which made it necessary to call in 

 extraneous aid for the descriptive part of the work. Of 

 the volume now before us, the first two-thirds, to which 

 alone the title of the book is properly applicable, completes 

 the account of the volcanic rocks of the Cape Colville 

 Peninsula. As before, the petrographical descriptions are 

 by Prof. Sollas, and the notes relative to locality and 

 occurrence by Mr. McKay, who also furnishes a clear geo- 

 logical map of the district. The details of mineralogical 

 composition and micro-structure do not include much that 

 is new, though we may mention the occurrence of a felspar 

 of the anorthoclase type in some of the rhyolites, the 

 frequent association of hornblende (or its pseudomorphs) 

 with hypersthene in the andesitic rocks, and the presence 

 of olivine in certain basic hypersthene-andesites or hypers- 

 thene-basalts. The interest of this collection of Tertiary 

 andesites, dacites, and rhyolites lies, not so much in any 

 novelty which they present, as in the close resemblance of 

 the whole assemblage from this " petrographical province " 

 to familiar types from better-known areas, such as 

 Hungary and the Great Basin of North America. 



The lack of arrangement and some minor blemishes, on 

 which we will not insist, are drawbacks doubtless in- 

 cidental to the conditions under which the work was 

 carried out, by the cooperation of a petrologist in England 

 with a field-geologist at the Antipodes. When this investi- 

 gation was taken in hand, Mr. McKay, we believe, 

 embodied in his own person the Geological Survey of New 

 Zealand, and the work must be considered a notable pro- 

 duction in these adverse circumstances. The re-organised 

 Geological Survey, under the directorship of Dr. J. M. 

 Bell, has begun operations with greater advantages, and 

 two important memoirs of the new series have already 

 appeared. 



A special feature of the present work is the profusion 

 of plates. This was not, we understand, a part of the 



1 "The RocV5ofCape Cr-lvll'e Penlniub, Auckland, New Zealand." By 

 Prof. Sollas, F.R.=. ; with an Introduction and Desrrirti've Note<i by 

 Alexander McKay. Vol. ii. Pn. 215 : with geological map and tft pbolo- 

 graphic plates of rcck-sections. (Wellington, N.Z. : J. McKay, igcd.) 



NO. 1969, VOL. 76] 



original design, but it greatly enhances the value of the 

 book. In the two volumes more than two hundred full- 

 page plates are devoted to the illustration of the volcanic 

 rocks of the Cape Colville Peninsula alone. The thin 

 slices have been photographed with polarised light, usually 

 with an amplification of sixty diameters, and most of the 

 plates are very successful in rendering the micro-structure 

 of the rocks selected. Such a collection of illustrations 

 is welcome independently of the immediate object of the 

 book, and the fact that most of the rocks belong to types 

 of world-wide distribution is, from this point of view, an 

 advantage. 



The latter part of this volume is devoted to the descrip- 

 tion and illustration of various rocks from numerous places 

 in New Zealand. Some of these, from the Kaimanawa 

 Mountains and other localities in the North Island, are 

 volcanic rocks generally comparable with those of Cape 

 Colville. Other descriptions are included here, without 

 regard to relationship, to fill out the volume, and the 

 want of any orderly arrangement gives a somewhat con- 

 fused appearance to this section. Some remarkable 

 teschenites are described from the east coast of Wellington 

 Province. They appear to occupy the neck of an old 

 volcano, and it is noteworthy that, like the similar rocks 

 from some European localities, they are referred to a 

 Cretaceous age. Special interest attaches to a collection 

 of crystalline schists from Westland Province, on the west 

 side of the South Island. In addition to garnetiferous 

 mica-schists, epidote-amphibole-schists, and other ordinary 

 types, there occurs a series of schistose ultrabasic rocks 

 composed of serpentine, talc, tremolite, calcite, &c. 

 Through the same district there runs also a belt of massive 

 ultrabasic rocks, viz. fresh and altered dunites. The geo- 

 logical relations of these two very interesting groups are 

 only briefly touched in this work, but they are fully dis- 

 cussed in the first Bulletin (new series) of the Geological 

 Survey, already mentioned. 



Prof. Sollas 's investigations, while devoted mainly to 

 the exhaustive description of one group of rocks, afford 

 also a glimpse of the rich variety of material which New 

 Zealand offers to the petrographer. When we recall 

 further the widely different " petrographical province " of 

 Dunedin, characterised by highly alkaline rock-types, some 

 of which have recently been described by Dr. Marshall, 

 we may expect that a more comprehensive examination 

 of the igneous and crystalline rocks of the colony will 

 result in further important additions to petrological 

 science. A. H. 



UNSOLVED PROBLEMS IN THE DESIGN 



AND PROPULSION OF SHIPS} 



'X'HERE are but few problems in the design of ships, as 



-^ in most other branches of engineering, that can be 

 exactly or completely solved in the full scientific meaning 

 of the word, and those are of a secondary character. The 

 primary or fundamental problems of safety, strength, speed, 

 and steadiness at sea arc far too complicated to bring 

 under anything like general mathematical treatment. The 

 results obtained by the most advanced calculations cannot 

 be applied directly to the real conditions of a ship at sea. 

 ."Xfter all is said and done, they merely relate to hypo- 

 thetical cases which arc simple in character and are 

 amenable to mathematical treatment. Some of these calcu- 

 lations are very elaborate, and their elaboration may some- 

 times tend to magnify their importance. The real problem 

 is often very imperfectly dealt with after they are made, and 

 it can only' be solved approximately for working purposes 

 by accepting the results of calculation for what they may 

 be really worth, judging of the allowances required for their 

 incompleteness, and using them in a scientific way and a 

 scientific spirit to arrive at safe conclusions. We are 

 obliged to come to a conclusion somehow, because we 

 have to build ships as well as we can, whether we can 

 solve exactly all the problems that arise in their design 

 or not ; and we have to take the responsibility of guarantee- 

 ing results, however diflicult to obtain, or of declining to 

 do so, within the time allotted for the preparation of 



1 Abridged from the "James Forrest" Lecture, delivered before the 

 Institution of Civil Engineers on June 18, by Dr. Francis Elgar, F.R.S. 



