78 ANNUAL RECORD OE SCIENCE AND INDUSTRY. 



and endeavored to take account of the evaporation. He 

 finds that soil covered with forests receives six tenths of the 

 whole quantity of rain that falls, the foliage of the trees hav- 

 ing intercepted four tenths. The hygrometric observations 

 show that there is always in the neighborhood of the forests 

 a greater quantity of atmospheric vapor tlian in the neigh- 

 borhood of cleared lands ; and this envelope of moisture is 

 beneficial to the neio'hboringr cultivated lands, as it flows out 

 upon them during the night-time when such lands are cooled 

 by nocturnal radiation, and the moisture is precipitated upon 

 them as dew. 6 B, LXXX., 206. 



CHANGES IN THE EARTH's AXIS OF ROTATION". 



The excellent investigation ofDr. Nyren upon the latitude 

 of Poulkova and its apparent variability was briefly noticed 

 by us at the time of its appearance ; but the essay itself hav- 

 ing recently come to hand, we w^ill not forbear to mention 

 that he has therein quoted numerous examples of the results 

 found by many astronomers, all tending to show changes, 

 and, in general, diminutions in the latitudes of the observa- 

 tories of Europe. The special results for Poulkova, as de- 

 duced from the observations of Peters, Gylden, Nyren, and 

 W. Struve, would lead us to conclude that there is even 

 some probability that the variability of the latitude of this 

 observatory may be an apparent one only, and be due rather 

 to some slight error in the adopted value of the precession and 

 nutation. The definitive determination of this point can prob- 

 ably only be reached by observations conducted uniformly 

 at all seasons of the year through a number of years. Nyr^n^ 

 Die Polhohe von Pulkowa. 



METEOROLOGY IN GERMANY. 



The German Seew^arte, at Hamburs:, now under the eren- 

 eral direction of the Imperial Hydrographic Oflice, has in a 

 recent circular announced the further extension of its work. 

 The first article relating to its organization being now in 

 course of execution, in accordance with which it has proceed- 

 ed to develop the system of observations and reports for 

 ocean vessels, and has also established complete collections 

 of charts and works relating to navigation, Avhose use is free 

 to all vessels in the various German ports, the office has now 



