142 F. Waldo — Bruckner *s Klimaschwankungen. 



instituted by man. His book,* which contains the results of 

 his investigation, is a real contribution to the steady advance- 

 ment of our knowledge of the subject, and is not merely the 

 working out of a theory based upon an hypothesis which may 

 be at any time overthrown by new discoveries or new ideas. 

 The amount of work necessary to present the matter in the 

 shape given by Dr. Bruckner can be judged only by those who 

 have undertaken researches of the same nature, but, as may 

 confidently be said, of less extent. The sub-topics of the book 

 are : 



Chapter I. The present condition of the question. Chapt. II. 

 Oscillations of the Caspian Sea. Chapt. III. The secular oscil- 

 lations of lakes having no outlet. Chapt. IV. The secular 

 oscillations of rivers and lakes with outlets. Chapt. V. Secular 

 oscillations of rain-fall. Chapt. VI. Secular oscillations of air- 

 pressure. Chapt. VII. Secular oscillations of temperature. Chapt. 

 VIII. Periodicity of oscillations of climate, derived from obser- 

 vations of river ice, dates of the grape harvest, and the frequency 

 of severe winters. Chapt. IX. The significance of oscillations of 

 climate for theoretical and practical purposes. Chapt. X. Oscil- 

 lations of climate of diluvial times. Review of the results ob- 

 tained. Graphical presentations. 



In the general statement of the work that had been pre- 

 viously done, as given in Chapt. I, we obtain a good idea of 

 the extent of the preliminary work done by the author in 

 preparing for his own investigations. The most important 

 literature is certainly embraced in the several hundred titles 

 referred to, and the very condensed summary of the main 

 results of each (pertaining to the question under discussion) 

 shows a good grasp of the matter. In some cases, however, 

 minor and comparatively unimportant contributions are men- 

 tioned with the same degree of deference as that given to very 

 exhaustive pieces of work, and without an actual reference to 

 the works themselves the reader may be misled into giving too 

 much weight to the contradictions of the latter by the former. 



In carrying out his own work, Dr. Bruckner has given most 

 valuable critical opinions of the materials and studies on 

 which he has based his researches ; and his estimates of their 

 individual worth are the results of painstaking and in most 

 cases time-consuming investigations. 



As a final table of the oscillations of the surface of the 

 Caspian Sea, Bruckner gives : 



* Klimaschwankungen seit 1700 von Dr. Eduard Bruckner, Penck's Geograph- 

 ieche Abhaudlungen, Band IV, Heft 2, Wien, 1890, (Ed. Holzel.) 



