18 



SCIENCE 



[N. S. Vol. LII. No. 1331 



in successive years." Even for the same 

 stream floods are a local phenomenon. An 

 example of this is the record for Cincinnati 

 and Pittsburgh, both on the Ohio Eiver: the 

 ten greatest floods are arranged in order of 

 their magnitudes for the two stations (many 

 other stations are tabulated in the paper), 

 with the following result: 



of causes which may cause a maximum flood 

 are very much more limited than the number 

 of combinations which may cause ordinary 



NOTES 



The spring announcement of MacMillan 

 books contains the notice of a text-book on 

 "Agricultural Meteorology," by Professor J. 



Of the European rivers, the Danube, the 

 Seine, the Neckar, the Ehine and the Main are 

 investigated. The records of floods in these 

 rivers extend back many centuries and would 

 provide ample data for any periodic recur- 

 rence, but these also are found to be depend- 

 ent upon the nature of the watershed and the 

 rainfall distribution. The conclusions derived 

 from the paper are: 



1. The records of both American and European 

 rivers show an average of 7 to 10 great floods per 

 century. 



2. Great floods are primarily due to precipita- 

 tion, and that precipitation, in the form of rain, 

 which produces floods may be of two distinct types, 

 (a) so intense and widely distributed as to pro- 

 duce flooding regardless of antecedent conditions; 

 (6) moderate rains continued intermittently for 

 eight to ten days or more with antecedent condi- 

 tions favorable to high run-off. 



3. There does not appear to be an orderly pro- 

 gression in the magnitude of floods with the lapse 

 of years; that is to say, the absolute maximum 

 flood of any 100-year period is not necessarily 

 greater than the absolute maximum flood for the 

 preceding 100 years. 



4. The magnitude of great floods with respect to 

 the average annual flood, seems to increase in geo- 

 metrical progression but apparently wholly regard- 

 less of the flow of time. 



5. Great floods like great rainfalls are essentially 

 a local phenomenon even for the same Stream. 



This paper was discussed by Mr. Eobert E. 

 Horton,^ the hydrologic engineer, who is of 

 the opinion that the occurrence of maximum 

 floods is fortuitous and that the combinations 



Warren Smith, of the United States Weather 

 Bureau. This is the first text-book exclu- 

 sively devoted to this subject and is certain 

 to find a large demand, not only from agri- 

 cultural colleges and universities, but also 

 from the farmer and general reader, to whom 

 it will be of practical value. 



In the October, 1919, Monthly Weather 

 Review, there are several short articles and 

 abstracts on forecasting from local signs, 

 such wind direction, clouds, pressure change, 

 clouds, sky colors, and the scintillation of the 

 stars. It is interesting to note the difference 

 in character of the forecasting problems in 

 Europe, where data is incomplete from the 

 west, and in America, where more data is 

 available but a greater diversity of local prob- 

 lems is encountered, n t^tj^^ -»j-™.,„,«™. 

 G. LeKoy Meisinger 



Washington, D. C. 



SPECIAL ARTICLES 



A SIMPLE METHOD FOR TITRATING ELECTRO- 



METRICALLY TO A DESIRED END POINT 



IN ACID-ALKALINE REACTIONS 



SoRENSEN^ and Clark and Lubs^ have pub- 

 lished detailed directions for the preparation 



1 Sorensen, "Tiber die Messung und Bedeutung 

 der Wasserstoffionenkonzentration bei biologischen 

 Prozessen, " Ergebnisse d. Physiologie, 12, 393, 

 1912. 



2 Clark and Lubs, ' ' The colorimetrie determina- 

 tion of hydrogen ion concentration and its appli- 

 cation in bacteriology," Jour. Bacteriology, 2, pp. 

 1, 109, 191, 1917. 



Ibid., pp. 866-867. 



