Jtilt 3, 1908] 



SCIENCE 



21 



the limit and will probably enable such craft 

 to cruise about three quarters of the days of 

 the year. A misprint on page 63 states the 

 length of the German " Zeppelin " as 85 feet 

 instead of 414 feet. 



A rather scant chapter follows on flying 

 machines, but it can be profitably studied to 

 ascertain the various steps which have led to 

 the success of the last two years. 



After devoting one chapter to kites and 

 another to parachutes, both of which are fairly 

 well written, the author passes to military 

 ballooning, in which he is evidently thor- 

 oughly proficient. He takes up its develop- 

 ment, describes its uses in the Franco-Prus- 

 sian war, and then devotes two chapters, the 

 ablest in the book, to the modern organization 

 of military ballooning in some fourteen dif- 

 ferent countries. This brings us to chapter 

 XVI., Balloon Construction and the Prepara- 

 tion of the Gas, followed by one on Instru- 

 ments, and then follows Ballooning as a Sport, 

 in which the author is evidently an adept, 

 having made many such expeditions and re- 

 lating them in an entertaining way. 



Chapter XIX., on Scientific Ballooning de- 

 scribes the various journeys (in some of which 

 the scientists lost their lives) made to ascer- 

 tain the laws of decrease of air pressure, of 

 temperature changes, of saturation, of the 

 composition of the air, of its electrical and its 

 acoustical properties. The greatest authentic 

 height attained by man has been 35,500 feet, 

 while kites have been flown to 21,100 feet and 

 unmounted balloons with recording instru- 

 ments (ballons-sondes), have reached 85,000 

 feet (16.1 miles) and have furnished data 

 which will presently be utilized in foretelling 

 the weather. 



The next six chapters treat of balloon 

 photography, of the outfit required, of the 

 interpretation of photographs, of the uses of 

 kites and of the methods for interpreting the 

 bird's-eye views obtained for topographical 

 purposes, in all of which the author is evi- 

 dently an expert. He has also had much ex- 

 perience with carrier pigeons and devotes a 

 chapter to them. The reader may be sur- 

 prised at the statement quoted that the mean 

 speed of these birds is only about 26 miles 



an hour; feats mentioned in sporting books 

 having been probably accomplished by the aid 

 of the wind. Swallows fly faster than 

 pigeons, but efforts to train them have failed 

 so far. 



The last chapter is on Balloon Law. The 

 author states that such law can hardly be 

 said to exist, but " that some sort of inter- 

 national regulation will be necessary in the 

 future, seeing that balloons are now much 

 more common than they were and that the 

 dirigible air-ship is a practicable possibility." 



The book is well written and well translated. 

 Its perusal will enable the reader to follow 

 understandingly the great advances since 1906 

 which are now in process of evolution. 



0. Chanutb 



Chicago, III. 



Laboratory Exercises in Physical Chemistry. 



By Frederick H. Getjian, Ph.D. Second 



Edition. Pp. x + 285. New York, John 



Wiley & Sons. 1908. 



The first edition of this laboratory manual 

 was issued in 1904. Its author had set for 

 himself the task of selecting for American 

 students only such exercises as are typical, 

 describing these in the clearest way possible, 

 giving all reasonable discussion of theory and 

 directions for work, and saving the student 

 the labor of searching out his needs in such 

 volumes as Ostwald's " Physiko-Chemische 

 Messungen " and Traube's " PhysLkaliseh- 

 Chemische Methode." These must continue 

 to be standard authorities, but with such 

 wealth of detail and so many references to the 

 German literature of the subject as to be 

 often discouraging to the student who is not 

 already well advanced. 



While physical chemistry is now fairly dif- 

 ferentiated as an individual branch of phys- 

 ical science, a laboratory manual on this sub- 

 ject is necessarily restricted in range, and the 

 demand for it can never be large. Dr. Get- 

 man's aptness in clear statement and good 

 arrangement is manifest, even without more 

 than a cursory examination of the book. The 

 best evidence that he was successful in giving 

 satisfaction to students of his favorite sub- 

 ject is the unexpected discovery that a new 



