700 



SCIENCE. 



[N. S. Vol. XXII. No. 570. 



the volume before us, ' The text-book is in- 

 tended chiefly for the use of students who lay- 

 most stress on the study of the experimental 

 part of physics, and who have not yet reached 

 the stage at which the reading of advanced 

 treatises on special subjects is desirable.' 

 With this end in view special attention is 

 given the description of the fundamental ex- 

 periments and special emphasis is laid upon 

 the various assumptions, and the conditions 

 under which the different theories hold. 



It is of interest to note the order of arrange- 

 ment of the matter in a text-book written by 

 men so well known as teachers as well as in- 

 vestigators. There are in all twenty chapters, 

 and their contents may be outlined as follows : 

 Discussion of temperature; expansion with 

 rise of temperature; quantity of heat, con- 

 ductivity; conservation of energy; the kinetic 

 theory of matter; change of state; radiation 

 and absorption; thermodynamics, radiation. 



A better order for the presentation of the 

 subject of heat could hardly be imagined; and 

 as one reads the chapters it is only at rare 

 intervals that one feels called upon to offer 

 any criticisms or to make any comments 

 which are not most favorable. It may not be 

 amiss to mention as being worthy of special 

 praise the treatment of such subjects as 

 the kinetic theory of matter, radiation, the 

 porous pkig experiment, the discussion of 

 various phenomena in meteorology, the sphe- 

 roidal state, and the theory of the radiometer. 

 The most valuable feature of the book is un- 

 doubtedly the exact statement of the various 

 theories and their limitations. Thus, in 

 speaking of the radiometer, the authors say: 

 " The theory is altogether beyond our scope, 

 but the following account of what occurs may 

 give some idea of the action. It is to be re- 

 membered that it is an account and not an 

 explanation." Various sentences like this may 

 be found throughout the book, and any stu- 

 dent must be impressed with the great care 

 taken to give a true account of both experi- 

 ments and theory. There is one criticism, 

 rather general in its nature, which may be 

 passed upon the whole book, and that is that 

 too much attention is given experiments and 

 observations of former days at the expense of 



more modern work. It does not seem alto- 

 gether advisable to discuss so fully experi- 

 ments which were incomplete or mathematical 

 laws which have been shown to represent the 

 truth imperfectly. This is specially marked 

 in the chapter on radiation. Again, in the 

 description of certain forms of instruments, 

 care is not taken to explain certain essential 

 features in their accurate use, as, for instance, 

 the Bunsen ice calorimeter. It would have 

 been well, further, in discussing the difficul- 

 ties of calorimetry to say a few words con- 

 cerning the instrument perfected by Water- 

 man. In the chapters dealing with the spe- 

 cific heat of water and the mechanical equiva- 

 lent of heat good, bad and indifferent experi- 

 ments are all described together, and a student 

 is not told which are the best. If so many 

 experiments and observations are to be de- 

 scribed, it certainly would be best for a stu- 

 dent to be told which are designed with the 

 greatest care and which are the most trust- 

 worthy. 



These slight criticisms are not meant in any 

 way to reflect upon the excellent character of 

 the book. As a text-book it stands by itself 

 and should be put in the hands of every stu- 

 dent of physics early in his course. 



J. S. Ames. 



Minnesota Plant Diseases. By E. M. Free- 

 man, Ph.D., Assistant Professor of Botany, 

 University of Minnesota. Report of the 

 Survey, Botanical Series, V. St. Paul, Min- 

 nesota, July 31, 1905. Pp. xxii + 432. 8vo. 

 From time to time, it has been the pleasant 

 task of the writer to notice the publication 

 of the Botanical Survey of Minnesota, and to 

 comment upon the thoroughly satisfactory 

 style of publication adopted by the director. 

 Professor Conway Macmillan, of the Univer- 

 sity of Minnesota. The volume now before 

 us fully maintains the high standard set by 

 the previous publications in this series. In 

 its paper, type, ilkistrations and binding, this 

 volume leaves nothing to be desired. As one 

 turns over the pages, he is struck by the uni- 

 formly high quality of the illustrations, 

 whether they are cuts from line drawings, or 

 half-tones from photographs. They are all 



