November i8, 1920] 



NATURE 



371 



Principles and Practice of Aerial Navigation. By 



Lieut. J. E. Dumbleton. Pp. vii+ 172 + v plates. 



(London : Crosby Lockwood and Son, 1920.) 



Price 1 2 J. 6d. net. 

 Ordinary navigation may be broadly divided into 

 two kinds : coastal navigation, in which, shaping 

 his course by compass, the mariner verifies his 

 position by cross-bearings of two terrestrial ob- 

 jects, by two objects in transit and the bearing of a 

 third object, and by various other methods ; and 

 navigation of the open sea, with no lights or head- 

 lands available, so that he has to depend wholly 

 upon celestial observations. With regard to long 

 voyages of the second type, but little progress 

 has been made in air matters, difficulties as to 

 obtaining a satisfactory horizon having so far 

 proved insuperable. It is upon the development of 

 directional wireless that the hopes of the airmen 

 are fixed in connection with long-distance aviation 

 in the immediate future. 



It is therefore to navigation of the coastal type 

 tliat the airman has given special attention, and 

 here it is evident that not only has he availed him- 

 self fully of methods already in use, but has also 

 not failed to improve upon these processes. 



On p. 90 we have an example of this in the 

 <-oursc and distance indicator, an instrument which 

 from a given course and an air speed calculates 

 the course to steer and the ground speed. So also, 

 f)n p. 64, we have a most useful problem, not to 

 l>e found in navigation books, for finding by three 

 l>earings of the same object the course made over 

 the ground. As presented in the book, to be 

 (lone by protraction it would seem a little com- 

 [)licated for use in a heavier-than-air machine, but, 

 reduced to the form of a table, it should be of very 

 C'reat utility by sea or air. 



The book is clearly written and altogether a 

 highly creditable production, and should prove at- 

 tractive not only to airmen and seamen, but also to 

 all who take an intelligent interest in the develop- 

 ment of aviation on ihe scientific side. 

 R"Sfs ; Their History, Development, and Cultiva- 



I I'm. By the Rev. Joseph H. Pemberton. 



Secoiui edition. Pp. xxiv-(- 334-^9 plates. 



(London: Longmans, (ireen, and Co., 1920.) 



Price 15^. net. 



The demand for a second edition of the Rev. J. H. 

 Pemberton 's useful book on roses is a welcome 

 sign that there are still a considerate number of 

 keen gardeners who are interested in the genus, 

 not so much on account of its horticultural merits, 

 but rather because of its botanical interest. The 

 various species of the genus Rosa, unspoilt by the 

 hybridiser and "improver," are well worthy of 

 cultivation, and it is to be hoped that this book 

 will turn many to the study of the wild species, as 

 well as to the interesting hybrids that have been 

 derived from them. 



In garden catalogues of a hundred years 

 ago the "old-fashioned " roses were the pride of 

 the collections, and one would like to see such 

 collections revived, difficult as it may be now to 

 pro<;ure some of the earlier forms. 

 NO. 2664, VOL. 106] 



Few people to-day have seen Rosa hemi- 

 sphaerica in all its glory, nor do they know the 

 beauty of the various forms of the Scotch rose, or 

 of R. damascena or R. indica. To most, prob- 

 ably, the charming little rose de Meaux (R. centi- 

 folia Pomponia), given in the list of grand- 

 mother's roses, is scarcely known, and the same 

 may be said of the greater number given in this 

 interesting list of old garden favourites. 



This second edition does not differ on general 

 lines from its excellent predecessor, but a good 

 deal has been added on the perpetual flowering 

 musk roses, which the author himself has done 

 so much to popularise ; and on the hybrid lutea 

 roses. Some useful additions have been made to 

 the section dealing with fungus pests and to the 

 chapters on soils and manures. 



The appendix, giving a list of selected roses, 

 has been revised, and forms a valuable guide to 

 those who wish to grow the best types of garden 

 roses. 



Pyrometry: A Practical Treatise on the Measure- 

 ment of High Temperatures. By Chas. R. 

 Darling. Second edition, revised and enlarged. 

 Pp. xii + 224. (London: E. and F. N. Spon, 

 Ltd. ; New York : Spon and Chamberlain, 1920.) 

 Price los. 6d. net. 



The publication of the first edition of Mr. 

 Darling's book on pyrometry in 191 1 filled a want 

 in English technical literature at a time when 

 the value of a more exact measurement of tempera- 

 ture in industrial operations was being appre- 

 ciated. Mr. Darling points out in his preface to 

 the new edition that since his book was first issued 

 there has been a great extension in the use of 

 pyrometers in industrial processes and laboratory 

 work, and there can be little doubt that his book 

 has contributed in no small measure to this de- 

 sirable development. He further refers to the in- 

 valuable uses of pyrometers during the war, and 

 it is pleasing to have his testimony that British 

 makers were fully able to meet the demand for 

 instruments. In his revision Mr. Darling has 

 described several instruments of the more recent 

 pattern, and added new material, bringing the 

 book thoroughly up to date. The bulk of the 

 new matter is to be found in the chapter dealing 

 with thermo-electric pyrometry, and valuable and 

 suggestive additions have been made, particularly 

 on the use of base-metal junctions and on pro- 

 tecting sheaths for couples. In the chapter on 

 optical pyrometers there has been considerable 

 extension, especially of the section on colour ex- 

 tinction instruments, the simplicity of which is a 

 strong point. 



Co-education and its Part in a Complete Educa- 

 tion. By J. H. Badley. Pp. 39. (Cambridge : 

 W. HefTer and Sons, I.td., 1920.) Price 2s. net. 



This 19 an address delivered at Cambridge on 

 February 22 of this year to a meeting of the 

 "Socratic" Society by the headmaster of the well- 

 known Bedales School, with the addition of some 

 notes, which appear at length in the appendix. 



