122 



NA TURE 



[June 9. 1904 



followed by naval architects in endeavouring to secure 

 good qualities in ships. For instance, Prof. Peabody, 

 when dealing with the question of " metacentric 

 heights," which are the measures of the " stiffness " 

 of ships, their power to resist inclination under the 

 action of external forces, states that, in practice, this 

 height " is seldom less than \\ feet and seldom more 

 than 5 feet unless it be in special forms," and then 

 remarks that " it appears that the metacentric height 

 for steamships is somewhere near the same for all 

 steamships whatever their size," which is obviously 

 incorrect on his own showing, and might easily lead 

 students to conclude that little importance attaches to 

 the value of the metacentric height within a very wide 

 range; whereas it is absolutely certain, and is else- 

 where recognised by Prof. Peabody, that the more 

 moderate the metacentric height the greater is the 

 probability of steadiness in a seaway. He also states 

 that " metacentric height may be controlled by vary- 

 ing the proportion of beam to length," and does not 

 specifically direct attention to the much greater 

 influence of variation in the proportion of beam to 

 draught. 



In another passage he refers to the characteristic 

 features in the curves of stability of sailing ships and 

 steamships, and makes the generalisation that this is 

 chiefly due to the greater metacentric height and 

 greater freeboard of sailing ships ; whereas it is 

 perfectly well known that other considerations have 

 larger practical effect on the curve of stabilit}'. Many 

 sailing ships having great range of stability have only 

 very moderate metacentric heights and moderate free- 

 board. Few allusions are made to the details of 

 practical shipbuilding, and some of these indicate that 

 the author can have had but little experience in the 

 conduct of actual work. 



These criticisms are not intended to indicate any 

 general disapproval of the scope or character of the 

 book. It is no doubt intended to be used as an 

 auxiliary to class-teaching by competent professors, 

 and for this purpose it will be extremely useful. It 

 also compiles and brings together much information 

 appearing in the Transactions of the English Institu- 

 tion of Naval .•\rchitects or of similar societies in other 

 countries, and practically reproduces the essential parts 

 of standard treatises by other authors on particular 

 branches of the subject. Prof. Peabody makes no 

 claim to originality, and states frankly that free use 

 has been made of numerous works on naval archi- 

 tecture, as well as of original articles and memoirs. 

 His readers have to thank him for the labour he has 

 bestowed upon this task, and, as a compilation, the 

 book will be useful for reference to naval architects 

 generally. But it does not profess to be — nor, indeed, 

 within its compass could it possibly be made — a com- 

 plete treatise on the modern theory of naval archi- 

 tecture. Such a treatise has yet to be written, and 

 the advances made in recent years in both the theory 

 and practice of ship construction have been so con- 

 siderable that the work of preparing it would be very 

 heavy. It is wanted, however, and no doubt will 

 eventually be produced. W. H. White. 



NO. 1806, VOL. 70] 



NEW ELECTRICAL TEXT-BOOKS. 



A Text-book of Static Electricity. By H. Mason. 

 Pp. vi+ 155. (New York : McGraw Publishing Co., 

 1904.) Price 2 dollars. 



Dynamo, Motor, and Switchboard Circuits. By W. R. 

 Bowker. Pp. xi-l-120. (London: Crosby Lock- 

 wood and Son, 1904.) Price 6s. net. 



Testing of Electromagnetic Machinery and Other 

 Apparatus. By B. V. Swenson and B. Franken- 

 field. Pp. xxiii + 420. (New York: The Macmillan 

 Co. ; London : Macmillan and Co., Ltd., 1904.) 

 Price I2S. 6d. net. 



Tlic Alternating Current Transformer. By F. G. 

 Baum. Pp. vii+195, (New York: McGraw Pub- 

 lishing Co., 1903.) Price 1.50 dollars. 



The Induction Motor. By H. B. de la Tour. Trans- 

 lated by C. O. Mailloux. Pp. xxvii + 200. (New 

 York : McGraw Publishing Co., 1903.) Price 2.50 

 dollars. 



' I 'HE subject of electrostatics is not per se one of 

 -'■ very great importance either to the electrical 

 engineer or the student of electricity, and it is open to 

 question whether a text-book devoted to the ele- 

 mentary principles of the subject is much needed. 

 Still, there is something to be said for having collected 

 together between one pair of covers all the information 

 which is usually only to be found scattered somewhat 

 irregularly throughout the pages of a more comprehen- 

 sive manual. Mr. Mason opens with a discussion of 

 the general principles of electrostatics, and proceeds to 

 consider in more detail capacity, electrostatic instru- 

 ments, and static generators. The fact that there is not 

 very much to say and plenty of space in which to say 

 it has enabled the author to make his descriptions very 

 complete and clear, and the further advantages of large 

 type and numerous illustrations should help to make 

 the book a very useful work of reference. 



Mr. Bowker's book consists chiefly of diagrams of 

 connections, with short explanatory notes : the number 

 of different cases considered is very large — there are 

 over a hundred diagrams — and these cover practically 

 all the more important circuits w-ith which an elec- 

 trician is likely to have to deal, whether in direct cur- 

 rent, single phase, or polyphase work. We do not 

 doubt that the book will prove useful to those who are 

 concerned rather with connecting up machinery than 

 with electrical engineering, but we should hardly have 

 thought that the matter was of sufficient importance to 

 warrant its treatment as a separate study. 



The work on the testing of electromagnetic 

 machinery by Messrs. Swenson and Frankenfield is 

 the first of two volumes, and deals only with direct- 

 current machinery. It is a book which can be 

 thoroughly recommended to all students of electrical 

 engineering who are interested in the design, manu- 

 facture, or use of dynamos and motors. -After a brief 

 introduction, which contains, incidentally, some excel- 

 lent advice on the writing of reports (which advice, by 

 the way, the authors themselves transgress in the speci- 

 men report which they print), the authors give a series 

 of nearly a hundred tests, which are well chosen and 



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