B. TERRESTRIAL PHYSICS AND METEOROLOGY. 131 



during the quaternary periods were three or four times as 

 large as at present, may be explained by periodic changes of 

 position of part of the interior of the earth, rather than by 

 supposing great changes in the distance of the moon from 

 the earth. 7 A, XLVIIL, 204. 



THE DIMINUTION OF AVATER IN SPRINGS, RIVERS, AND WELLS. 



The report of Wex on the diminution of water in wells, 

 etc., presented to the Austrian government in 1873, was fol- 

 lowed by the appointment, at his request, of a commission of 

 engineers, to whom was intrusted the duty of carefully inves- 

 tigating the points raised by the author in his learned mem- 

 oir. So important did the matter seem, on account of the 

 long-matured views presented by Wex, that the commission 

 decided to fully investigate the matter. The rivers Danube, 

 Rhine, and Elbe were respectively assigned to certain engi- 

 neers, while others made measurements in relation to the Al- 

 pine streams and the glaciers, and others again undertook a 

 special study of the meteorological questions involved. 



During the past two years the committee has accumulated 

 a great mass of valuable material, and has presented a very 

 elaborate report on the subject, which was published in a re- 

 cent number of the Journal of the Austrian Engineers and 

 Architects' Association. The many details given in the re- 

 port of the committee may perhaps be summed up as fol- 

 lows : First, an increase is proved in the frequency and the 

 heights of floods in the rivers, as well as a diminution in the 

 altitude of the mean of low waters in most of the rivers and 

 streams of cultivated lands ; and all the evil consequences 

 depicted by Wex follow thereon ; second, the cause of the 

 injurious changes in the regimen of the rivers, in the drain- 

 age of swamps and morasses, in the sinking of lakes and 

 dikes, is principally to be found in the destruction of the 

 forests. These two points having been abundantly estab- 

 lished by a large corps of able engineers, the conclusions and 

 the recommendations of the Austrian committee become of 

 the greatest interest to other nationalities, since it is evident 

 that the same causes are at work elsewhere, and especially 

 so in America, to bring about the same disastrous results. 

 The committee recommend that on the one hand exact meas- 

 ures be made of all that relates to the hydrography of the 



