Chemistry and Physics. 75 



(i) the volume is complete in itself, so that it should enable the 

 beginner to acquire all the information necessary for the naviga- 

 tion of a ship in any ocean not too close to the poles of the earth, 

 (ii) it is assumed that the reader neither possesses nor desires 

 to acquire formal mathematical and astronomical knowledge, 

 (iii) the requirements of those who may study without a teacher 

 have received constant and special attention, and (iv) no attempt 

 has been made to include every method that can possibly be used 

 to navigate a ship but, on the contrary, the volume has been 

 limited to the methods at present considered the best by the most 

 reliable modern authorities. 



An idea of the scope of the text, and of the way in which 

 the above mentioned problems have been attacked, may be 

 gleaned from the titles of the chapters, which are : ' ' The Fun- 

 damental Problem of Navigation, Dead Reckoning without 

 Logarithms, Dead Reckoning with Logarithms, The Compass, 

 Coastwise Navigation, The Sextant, The Nautical Almanac, 

 Older Navigation Methods, Newer Navigation Methods, and A 

 Navigator's Day at Sea." 



The entire subject-matter is presented in a very readable, lucid 

 style, the last chapter being especially interesting. The con- 

 densed, but complete, tables extend from page 154 to page 322. 

 The only auxiliary book required by the novice is the nautical 

 almanac for the year in which the voyage is to be made. The 

 diagrams are clear-cut, and special care has been taken to reduce 

 the number of typographical errors to a minimum. It is thus 

 clear that the book seems very well adapted to attracting students 

 to the fascinating and important subject of navigation. 



h. s. u. 



8. Practical Pyrometry ; by Ervin S. Ferry, Glenn A. 

 Shook, and Jacob R. Collins. Pp. vii, 147, with 73 figures. 

 New York, 1917 (John Wiley and Sons). — In preparing the text, 

 the authors have kept in mind the needs of three distinct classes 

 of readers, namely — college students, technically trained men 

 who deal with processes involving high temperature determina- 

 tions, and relatively untrained observers. For the benefit of the 

 first two classes, the underlying principles and the theoretical 

 consequences of the same are fully discussed. The requirements 

 of the third class are met by descriptions of the various types 

 of apparatus, by explanations of the manipulation of the instru- 

 ments, and by directions for the performance of fourteen experi- 

 ments on calibration, temperature determinations, etc. 



The successive chapters deal respectively with : standard 

 temperature scales, resistance pyrometry, thermoelectric pyrom- 

 etry, radiation pyrometry, and optical pyrometry. The selec- 

 tion of material and the conciseness of presentation should 

 make the book very useful. On the other hand, the text is some- 

 what marred by lack of sufficient care in proof-reading. Most 

 of the slips are obvious, but a few of them tend to confusion of 



