June 19, 1890J 



NATURE 



171 



MACHINE DESIGN. 

 The Elements of Machine Design. By Prof. W. Cawthorne 



Unwin, F.R.S. (London and New York : Longmans, 



Green, and Co., 1890.) 

 ''T^HIS is the eleventh edition of an excellent and 

 *- most useful book for engineers and students in 

 the engineering departments in our technical colleges. 

 Prof. Unwin is so well known in the profession 

 that any work of his is sure to receive full attention 

 and careful study ; for even in the present day one un- 

 fortunately often sees machinery and engineers' tools, 

 the design and construction of which give us cause to 

 wonder how they manage to work at all. The author is one 

 of those Professors whose books are eagerly sought after 

 by practical men for guidance. To say this is to say very 

 much indeed, for engineers have to make their machines 

 " pay " and creditable to themselves ; a bad machine tool 

 in a shop is very soon found out by the repairs it requires, 

 and the quality of the work it can produce. 



In this, the new edition of the work, the author has 

 found it necessary to divide the book into two parts, the 

 first of which is now before us. It deals principally with 

 the general principles of design, fastenings, and trans- 

 missive machinery. 



The author, well knowing the conditions of every-day 

 Avork in the drawing office and shops, has, we are glad to 

 observe, used throughout the standard English units of 

 weight and length. Another .good point is that the 

 mathematics used in the calculations are well within the 

 range of the average engineer ; at the same time accuracy 

 is obtained in the results, although useless refinements 

 are omitted. 



In the chapters on rivetted joints, and the one on 

 journals and the friction of the same in their bearings, 

 the experimental results obtained from experiments in- 

 augurated by the Institution of Mechanical Engineers 

 are fully described and the results tabulated ; and they 

 are embodied in the chapters in many useful forms 

 suitable for the guidance of engineers. Under the head- 

 ing of rivetted joints, it may be interesting to observe 

 that the question of punching versus drilling steel or iron 

 plates has solved itself in, at any rate, one first class 

 bridge works in the north, and in this particular works 

 the invariable practice is to drill all the holes throughout 

 the bridge work because it is cheaper, with suitable 

 machinery, to do so. On p. 97 the author does 

 not say whether his remarks apply to boilers as well 

 as other constructions, but to punch an iron boiler-plate 

 is considered bad practice, and a punched steel plate, 

 even if it is annealed afterwards, certainly comes under 

 the same head. 



In most of the locomotive works in this country 

 the boilers are drilled, finally, after all the plates are 

 in position, the barrel being fitted to the fire-box casing 

 after each portion has been drilled ; and certainly no 

 good locomotive builder would use a punched steel plate 

 in a boiler, even after annealing. One eminent locomotive 

 superintendent, we believe, uses punched steel boiler shell 

 plates ; this is probably the only exception in this country, 

 and is generally considered risky and not sound practice. 

 On p. 140 the system of applying the direct stays to the 

 NO. 1077, VOL. 42] 



crown of locomotive fire-boxes might have been added 

 and illustrated with advantage. 



The illustrations are particularly good, and all represent 

 good practice. The thanks of engineers are due to 

 Prof. Unwin for placing within their reach a volume 

 in which theory and practice are judiciously treated to 

 their great advantage. N. J. L. 



OUR BOOK SHELF. 



Investigation of the Fur-Seal and other Fisheries of 

 Alaska. Report from the Committee on Merchant 

 Marine and Fisheries of the House of Representatives. 

 (Washington: Government Printing Office, 1889.) 

 The fisheries of Alaska are among the great questions 

 j of the day, and those of our legislators who wish to take 

 I part in the inevitable debate on the subject will do well 

 I to possess themselves of the present volume, and digest 

 the large amount of information that it contains. As is 

 well known, the fur-seal fisheries of the Northern Pacific, 

 which supply the ladies' jackets so much prized in Europe, 

 are rented by the Alaska Commercial Company, and 

 produce a considerable revenue to the United States. It 

 is therefore a standing grievance among our American 

 friends, that, as shown by the testimony collected in the 

 present Report, the number of seals on the Prybiloff 

 Islands, whence the principal supply is derived, "has 

 materially diminished during the last two or three 

 years." This is attributed to the fact that a large num- 

 ber of British vessels, " manned by expert Indian seal- 

 hunters," have frequented Bering's Sea, and destroyed 

 " hundreds of thousands of fur-seals." It is shown that, 

 of the seals thus killed on the ocean, not more than one in 

 seven is secured, because a wounded seal sinks so quickly. 

 Thus, for every thousand seal-skins realized by the British 

 sealing-vessels, some seven thousand seals are killed. 

 Now, during the three years 1886-88, it appears that the 

 number of what the Americans call " illicit skins " secured 

 by the British traders was over 97,000, so that, if these 

 calculations are correct, it follows that nearly three- 

 quarters of a million of fur-seals were destroyed by British 

 vessels during that period. American citizens, we are 

 told, " have respected the law, and have made no attempt 

 to take the seals." 



While we fully sympathize with the Americans in their 

 view that the fur-seal is a most useful animal, and deserves 

 protection by special legislation, it seems to be doubtful 

 whether they have any right, in their praiseworthy efforts 

 in this direction, to turn a large tract of the Northern 

 Pacific into a " mare clausum" without obtaining the 

 consent of other nations. But the arguments by which 

 they justify this somewhat strong proceeding are fully set 

 forth in the present volume, and deserve special study. 

 We may also commend Mr. Dunn's Report as containing 

 a large amount of information on the history and habits 

 of Callorhinus ursinus, and some excellently drawn illus- 

 trations of what the Americans consider to be the only 

 legitimate method of obtaining this animal's skin. 



Pond Life : Alga; and Allied Forms. By T. Spencer 

 Smithson. (London : Swan Sonnenschein and Co., 

 1890.) 

 "The Young Collector" series, to which this hand-book 

 belongs, deals generally with classes of objects which can 

 be permanently preserved. The present volume describes 

 plants which, as the author says, " are not well adapted 

 for preservation." His task, therefore, has been to give 

 an account of the structure and habits of these plants, 

 and to explain how they may be procured in the best 

 form for observation. He begins with information about 



