68 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



this chart, which is probably preliminary to a far more elab- 

 orate exhibit, is based on the returns during the six years 

 1864-1869, from the ninety-seven stations of the Switzerland 

 hydrometric commission of the "Naturforschende" Society. 

 A comparison of the data for some of the Swiss lakes with 

 those for the great lakes of America may prove of interest. 

 Thus we have the annual rain-fall for Lake Geneva, 39.4 inch- 

 es ; for Lake Neufchatel, 37.4 ; for Lake Zurich, 46.2 ; for the 

 Boden-See, 43.3 inches. On the other hand, we find from the 

 Smithsonian charts, for Lake Ontario, 32 ; for Lake Erie, 38 ; 

 for Lake Huron, 30 ; Lake Michigan, 30 ; Lake Superior, 28 

 inches; and for Salt Lake, Utah, 20 inches. 



The ratio of rain-fall to evaporation, and the resulting vol- 

 ume of water flowing into the rivers, are among the most in- 

 teresting of the questions that come before hydraulic engi- 

 neers. Mr. Benteli, the author of the Switzerland rain-chart, 

 lias studied the subject, and finds that in the area drained by 

 the Aar only eighteen per cent, of the rain-fall is lost by 

 evaporation ; the remainder flows into the river past the city 

 of Aarau. 



The neighborhood of th^ Grimsel, and of Mount St. Ber- 

 nard, is the region of the heaviest rain and snow fall in all 

 Europe, the annual fall being measured as 98.4 inches. The 

 Smithsonian rain-charts give 80 inches for the extreme north- 

 w^est coast of Washinsfton Territorv, and 60 inches for South- 

 ern Florida, as the points of heaviest rain-fall within the 

 United States. 3Iitth. naturforsch. Gesellsch.^ l^erne^ 18*71, 

 344. 



UNVAEYING COUESE OF CIEEUS CLOUDS. 



It seems to be generally admitted that there are two "cold 

 poles (points of minimum temperature) in the northern hemi- 

 sphere, one in Asia, and the other in North America, and 

 that from these the trade-winds radiate, regulating, as they 

 veer to one side or the other, the changes of the weather. 

 To complete the statement, attention is called to the fact that 

 it is extremely probable that the high cirrus clouds are unaf- 

 fected by the variation in course, between northwest and 

 southeast, which the trade-winds experience on the eastern 

 borders of the two great continents, but preserve the normal 

 direction imparted to them by the rotation of the earth 



