June 24, 1920] 



NATURE 



515 



are so graphically penned that one fancies one- 

 self at the author's side, watching^ intently the 

 behaviour of these attractive birds, and sharing- 

 with them the hopes, fears, and passions inci- 

 dental to all stages of their brief career in the 

 open, fraught as it is with constant danger from 

 hawk, weasel, fox, or sportsman, and yet alle- 

 viated by the intense joys inseparable from the 

 sharing with a mate the important duties of found- 

 ing a home and rearing a brood of tiny fledg- 

 lings. The book is not without its humorous side 

 too, as the reader will discover when smiling over 

 the "Misadventures of Bird-watching." While 

 the author is endeavouring to identify a pair of 

 warblers and to find their nest, he is himself 

 closely watched, in the first place, by a puzzled 

 keeper, who suspects him of poaching, and, 

 secondly, by an angry bull in unpleasant prox- 

 imity, to escape the unwelcome attentions of 

 which the enthusiastic naturalist has perforce to 

 bring into action his fullest powers of strategy. 



This well-printed and unusually attractive 

 volume can be recommended to the notice of all 

 lovers of Nature and Nature-lore, and the ap- 

 pearance of a further series of posthumous essays 

 will be very welcome. 



Our Bookshelf. 



Engineering Descriptive Geometry and Drawing. 



By Capt. Frank W. Bartlett and Prof. 



Theodore W. Johnson, Part i. Pp. vii + 206. 



Part ii. Pp. v -I- 207-374. Part iii. Pp. v-l- 



375-617 + xiv plates. (New York: John Wiley 



and Sons, Inc. ; London : Chapman and Hall, 



Ltd., 1919.) Price 275. 6d. net. 

 This book gives in full detail the elementary 

 courses of engineering drawing as taught to young 

 midshipmen in the Navy of the United States of 

 America. The instruction is arranged on the 

 assumption that the student is quite without know- 

 ledge or experience in the handling of drawing 

 instruments. Part i., occupying about a third 

 of the volume, treats of line drawing in pencil and 

 in ink, lettering, the use and care of instruments 

 and scales, and describes in the minutest detail 

 all the "tricks of the tool's true play" as wit- 

 nessed in the practice of the draughtsman's art. 

 In these pages the learner has virtually at his 

 elbow, for constant reference, the skilled crafts- 

 man and the experienced teacher. His progress 

 should be sure and rapid, even without much help 

 from an instructor. 



In part ii. the principles of projection and de- 

 scriptive geometry are unfolded in close relation 

 to the special needs of engineers. 



Part iii. is perhaps the most important section, 

 and the fourteen plates at the end give standard 

 dimensions of such things as bolts, nuts, rivets, 

 NO. 2643, VOL. 105] 



pipes, rolled sections, etc., as adopted by the 

 bureaux of the U.S. Navy Department. We 

 have in this part a finely graduated scheme of 

 work in which the student executes finished 

 drawings of machine details from his own di- 

 mensioned hand sketches of the actual parts; 

 becomes familiar with the tables of standards ; 

 is trained in the reading of drawings, etc. 

 Although the instructions are again minute 

 and full, almost sufficient for self-tuition, 

 there is no suspicion of spoon-feeding, and the 

 student is left more find more to his own resources 

 as he becomes fit. There are chapters on snips' 

 lines and on structural steel and iron work. 



The treatment of the subject has been evolved 

 gradually and embodies the results of much ex- 

 perience in class work. It is characterised by 

 thoroughness, and the text-book is a model of 

 what such a book should be. The volume ought 

 to be in the library of every technical school 

 and drawing class in this country. Teachers as 

 well as students could learn much from it. 



Intermediate Text-hook of Magnetism and Elec- 

 tricity. By R. W. Hutchinson. Pp. viii + 620. 

 (London : W. B. Clive ; University Tutorial 

 Press, Ltd., 1920.) Price Ss. 6d. 

 The writer of a book such as this is a little 

 handicapped by having to work in accordance 

 with schemes laid down by boards of examiners, 

 and has not quite a free hand in the arrangement 

 and development of his material. Covering the 

 subject up to the " Intermediate " standard, the 

 work is suitable more to the science student than 

 to the future electrical engineer, and in view of 

 the vastness of the field the author has been 

 obliged to cut down the practical parts of the 

 subject in order to provide space for the more 

 academical sections. It is not his fault that the 

 pith ball is made as important as the dynamo. 

 Nevertheless, we would urge that it is as essential 

 for the science student as for the engineer to 

 " think in volts and amperes " before he attempts 

 to grasp subtler refinements, and we should have 

 liked to see Ohm's law and the conception of 

 resistance introduced earlier than p. 304. In the 

 author's treatment of magnetism, on the other 

 hand, with which he commences his volume, he 

 boldly brings his reader face to face with the 

 equation B = 47rI-FH as early as p. 31, adopting 

 " an introductory elementary treatment to acquaint 

 the reader with the general meaning of the terms 

 in use," and giving the fuller treatment in its 

 proper place later. The idea is excellent, and 

 a similar scheme might have been applied to elec- 

 tric currents with advantage. 



Taken all round, the work is painstaking and 

 is skilfully compiled. Special attention should be 

 directed to the three concluding chapters on elec- 

 trical oscillations, passage of electricity through 

 gases, and radio-activity respectively, which form 

 admirable introductions to the portions of the 

 subject founded on the more modern researches 

 in physics. 



