6io 



NA TURE 



[Oct. 25, 1883 



Adriatic, which has evidently been compiled with a great 

 deal of care. The Italian local names in use on the 

 Adriatic coasts and the Croatian names are also gis-en ; 

 those of the latter dialect for the first time. 



The author commences with a short description of the 

 Adriatic Gulf. Its tides are inconsiderable, the normal rise 

 and fall being only i\ foot, and only one ebb and flow in 

 twenty-four hours. The currents, however, are numerous, 

 acting as modifiers of the effects of climate and influencing 

 by their agency the diffusion of marine life. The nature 

 of the sea bottom varies immensely, giving abundant 

 choice to the various species of fish. The sea water 

 r is, in respect of the degree of saltness, about the 

 same as the Atlantic under the tropics, but springs 

 abound in some regions to such an extent as to render the 

 surface water thereof quite fresh. With a for the most part 

 moderate depth, yet 100 fathoms is reached near the 

 islands of Zuri and Scoglio Porno, and near the island 

 of Meleda the bed has not been reached at 500 

 fathoms. 



In the second chapter we find a history of the present 

 state of the fisheries. The demand now exceeds the supply. 

 The decrease is ascribed to the effects of trawling, though 

 without the slightest reason. One great drawback to 

 the preserving of fish seems to be the State monopoly 

 of salt. Full details as to the fishing of Italian boats in 

 Austrian waters are also given. In the third chapter the 

 various fishing districts and their peculiar products are 

 detailed; besides fish, sponges are obtained in the vicinity 

 of Crapano and coral near Zlarin. Pola is the best dis- 

 trict in Istria for the tunny; it is now a town of 20,000 

 inhabitants, in 1856 it was a village of but 600 inhabitants. 

 In value the sardine fishery holds the first rank, being 

 computed at about 40,000/. a year, while the tunny fishery 

 yields about 15,000/., and the red mullet take is calculated 

 at 12,000/. The average annual value of squid (LoUgo 

 la) captured is 12.009/. The various sorts of craft 

 ^ used in fishing are described and figured in Chapter IV., 

 with calculations of their value, number of crew, &c. Nets, 

 basket traps, fish weirs and ponds are treated of in 

 Chapter V. The tanning process is effected by a solution 

 of the bark of Pinus maritimus in sea water, but for very 

 fine nets the leaves of the pistachio, shumac, myrtle, and 

 heath [Erica vulgaris) are used. Chapter VI. describes 

 the hooks and lines used. Chapter VII. treats of the 

 names applied to fishermen and various modes of fishing. 

 The fish markets of the Istrio-Dalmatian coast are de- 

 scribed in Chapter VIII. The well-defined sorts which 

 appear in these markets may be given at ninety fishes, 

 often uniting under one name various species of the same 

 genus, thirty mollusks, and ten Crustacea, but in addition 

 there will be found sea urchins (Echini), an actinia (A. 

 cereus), and such an ugly form as Ascidia })iicrocos)>uts. 

 The methods of curing and cooking fish are detailed in 

 Chapter IX. The curing of pilchards in oil after the 

 fashion of sardines seems to have met with a well-earned 

 success, but the tins have to be imported from England 

 and the oil from Italy or France. Chapter X. is devoted 

 to statistics ; those of the Austrian sea-fisheries are com- 

 piled with commendable exactitude and completeness, 

 and are regularly published in the Austria, the statistical 

 periodical of the Austrian Ministry of Commerce. We wish 

 that we could say the same for our British sea-fisheries. 



The very valuable appendix contains a catalogue of the 

 Adriatic marine fauna, and the local names given to the 

 best known forms. The typography and illustrations of 

 this handsome volume leave nothing to be desired even 

 in these days of luxurious editions. We agree with Dr. 

 Giinther in believing that to the great number of persons 

 who annually leave our shores for the Mediterranean in 

 quest of sport and recreation this work will serve 

 as a guide to a field of pleasant research, hitherto 

 much neglected. It is also a most important contribution 

 to the knowledge of the economic resources of the sea- 

 coast and rivers of a deeply interesting country, and we 

 hope that one of the results of its publication may be to 

 greatly develop a practical interest in the fish treasures 

 of the Adriatic Gulf. 



OUR BOOK SHELF 



Practical Electrical Units Popularly Explained. By 

 James Swinburne (late of J. W. Swan and Co., Paris; 

 late of Brush Swan Electric Light Company, U.S.A.). 

 (London and New York : E. and F. N. Spon, 1883.) 



The title of this book will doubtless lead those to whom 

 "ohms," " amperes," "farads," &c, seem so mysterious 

 to hope that all difficulty in understanding what they are 

 and whence they come will be removed. They will find, 

 however, that though the relations between the practical 

 units are given very clearly, and are illustrated by many 

 numerical examples, yet the definitions are " definitions 

 in a circle." Mr. Swinburne has neither shown how the 

 C.G.S. units are derived, nor has he even given the rela- 

 tions of the practical to the C.G.S. units. 



The mechanical units are fully described on the English 

 system, which perhaps is better suited for purposes of 

 explanation than the French, as being more familiar to 

 most people. In speaking of the term "electric fluid," 

 Mr. Swinburne uses this rather dangerous language ; 

 " Electricity can be looked upon as an imponderable fluid 

 which, like a gas, is compressible, the volume varying in- 

 versely as the pressure, so that if the pressure be doubled 

 the volume is halved." It does not appear at once to 

 what this refers, but six pages on the meaning is ex- 

 plained, for we read : " It may seem strange at first that 

 there should be a unit of quantity, and another of capacity 

 to hold that quantity, when we do not need to call a pint 

 measure by one name and the quantity of liquid it holds 

 by another. It must be remembered that electricity cor- 

 responds to a compressible fluid ; and though the pint 

 measure holds, or is supposed to hold, a pint of liquid, 

 the amount of gas it would contain would depend on the 

 pressure." This is one of the many excellent concrete 

 analogies by which Mr. Swinburne assists his readers to 

 understand those actions which at first seem to many so 

 unintelligible. 



It is not clear in what way the following note will assist 

 mechanical engineers or any one else to understand the 

 nature of electromotive force. " Force is generally 

 looked upon as what tends to move matter, and the term 

 ' electromotive force ' seems therefore a misnomer at first 

 sight. Science does not know what electricity is, but it 

 is supposed to be. a kind of motion of molecules or of 

 ether very closely related to heat and light. Science 

 knows little about molecules or ether, and does not even 

 know if there are such things, but thinks the next thing 

 to understanding anything is naming it." 



The book is not meant to be a scientific work, but is 

 intended to help mechanical engineers and others to 

 understand the units with which they may have to deal ; 

 for this purpose the simple language and the numerous 

 examples will be sure to make it succeed. C. V. B. 



