66 



NATURE 



[March i6, 191 6 



C. L. Feldkainp, have selected their entries from all 

 the material on frost and frost prevention under 

 American conditions that have come to their attention, 

 but disclaim any exhaustiveness for their list. A 

 brief indication of the scope follows each entry. The 

 arrang^ement is chronological and there is an index 

 arranged according to States. The paper should prove 

 useful to agriculturists. 



The Geographical Review is the new title under 

 which the Bulletin of the American Geographical 

 Society appears this year. An introductory note out- 

 lines the scheme of the remodelled publication. It is 

 hoped to broaden the range of the articles and to give 

 the notes and reviews a more critical and scholarly 

 qualit)-. A special feature is to be made of the biblio- 

 graphical section, which, in addition to the record of 

 books and maps, will contain an analysis of all the 

 principal geographical publications and those bearing 

 on geography. The classification adopted is a regional 

 one, and is illustrated in a sketch map in the January 

 issue. If the high standard aimed at is maintained 

 the Geographical Review should rank among the most 

 useful geographical publications and be of great assist- 

 ance in the study of the subject. The January num- 

 ber (vol. i., No. i), in addition to several shorter 

 articles, notes, and bibliography, contains a lengthy 

 paper by Mr. C. A. Cotton on fault coasts, with 

 special reference to New Zealand. 



An investigation of the world's coal resources was 

 undertaken by the twelfth International Geological 

 Congress, held in Canada in the summer of 1912, with 

 the view of estimating the tonnage available in known 

 fields. In October last the American Geographical 

 Society published in its Bulletin (vol. xlvii., No. 10) 

 a summary of the results, which have been embodied 

 in eoftcnso in a monograph of three volumes published 

 by Morang and Co., Toronto, 1913. The author of 

 this summary, Mr. Leon Dominian, finds that on 

 the basis of the present annual consumption of 1300 

 million tons, the world's coal supply is provided for 

 centuries. 



Bulletin 254 of the Scientific Papers of the Bureau 

 of Standards (Washington : Government Printing 

 Office, 1915) contains a stud}' of the qualities of 

 platinum goods, by Messrs. George K. Burgess and 

 P. D. Sale. The object of the investigations was in 

 the first place to devise a simple thermoelectric test 

 of the puritv of platinum, for which purpose the tem- 

 perature-coefficient of resistance and the thermoelectric 

 force were found useful ; in the second place, to inves- 

 tigate the loss of weight due to disintegration when 

 platinum vessels containing various proportions of 

 other metallic constituents are heated. 



In a series of articles in the February numbers of 

 the Electrician, Mr. W. R. Cooper has given an 

 account of the properties of selenium which will prove 

 of great value to all those who have in view the tech- 

 nical applications of the sensitiveness to light which 

 the material exhibits. Up to the appearance of these 

 articles it has been necessary to collect information 



NO. 2420, VOL. 97] 



on the subject from the pages of scientific journals 

 published in all parts of the world. Mr. Cooper's 

 articles now provide the information in a convenient 

 and readable form. After an account of the various 

 forms of selenium and the modes of preparation, their 

 sensitiveness to light in general aryd to variations of 

 the wave-length of the light are discussed. Although 

 a satisfactory general theory has not yet been evolved 

 from the experimental facts now available, there is 

 sufficient information about the behaviour of the mate- 

 rial to make it likely that its properties will before 

 long find for it some more extensive application than 

 at present, when it is mainly restricted to the auto- 

 matic lighting of isolated buoys at sea. 



We congratulate the Athenaeum on the promptitude 

 with which it has been able to publish its subject-index 

 to the Periodical, Scientific, and Technological Litera- 

 ture for 1915. The publication of this list within six 

 weeks of the close of the year indexed is a remarkable 

 feat. The list is by no means intended to be a com- 

 plete index to all branches of scientific literature, but 

 has special reference to the war in its technological 

 aspects. Indeed, a complete list of the scientific papers 

 published throughout the world in 1915 would probably 

 contain 40,000 names of authors, whereas in the 

 Athenaeum list we have rather fewer than 2000 names 

 quoted. The subject-index is arranged alphabetically. 

 The following examples of the headings for some of 

 the longer sections will give an idea of the character 

 of the subjects selected for indexing :—" Aeronautics," 

 "Agriculture," "Artillery," "Automobiles," "Birds," 

 "Coal," " Electric Apparatus," "Explosives," "Fores- 

 try," "Gas and Oil Engines," "Geology," "Mines," 

 "Railways," "Roads," "Submarines," "Telegraphs," 

 "Telephones," "Warships," and "X-Rays." The 

 articles indexed are taken from 215 periodicals, which 

 are mainly British, although thirty American and 

 seven French periodicals are included, as well as about 

 ten other foreign journals. 



Engineering for March 10 contains the last of a 

 series of articles on the w'hirling speeds of loaded 

 shafts ; these articles describe an investigation which 

 has been made at the Royal Technical College, Glas- 

 gow, by Mr. W. Kerr. Tests on a 250-kw. turbine, 

 and on a 3-h.p. de Laval turbine, showed some dis- 

 agreement with the usual theory, and led the author 

 to investigate the matter mathematically. It appears 

 that there is both experimental and theoretical evidence 

 of the existence of a critical speed for loaded horizontal 

 shafts which is considerably below that given by the 

 usual theory. This new critical sf>eed is due in the 

 first instance to the direct effect of gravity, which has 

 been hitherto neglected in the theory-. The lower 

 critical speed seems to be less important than the 

 higher, when it is merely a question of running through 

 in the process of speeding up. Also, it is of little im- 

 portance if the loads on the shaft are ven,- light. In 

 those cases in which it is shown clearly, it is probably 

 due to inaccurate balancing. In general, there will be 

 an undesirable instability at all speeds between the two 

 critical values, and it would be best to keep the normal 

 running speed outside this range. 



