1885.] METEOROLOGY. 377 



Meteorology. 



THE METEOROLOGIGAL SOCIETY OF BERLIN. 



OX January 6, Prof. Miittricli gave a sliort liistorical review of 

 the arrangements in connection with .seventeen forest 

 meteorological stations in Prussia. They were established on as 

 uniform a system as possible over regions of very wide varieties of 

 climate : on plains and at different levels above the sea, in districts 

 having a more continental, and in districts having a more oceanic, 

 climate, and in leaf and pine forests. In all these places, moreover, 

 observations were made according to precisely the same regulations. 

 Each station was twofold, having one equipment in the wood, 

 another in the open field; both, as a rule, at a distance of 200 

 metres from the edge of the wood. The observations comprised 

 the atmospheric pressure, the temperature of the air and of the 

 ground, the wind, moisture, cloudiness, atmospheric precipitation, 

 and the evaporation of an open mass of water. These observations 

 were made twice a day — at 8 a.m. and 2 p.m. The observations 

 thus obtained were collected at the station of Eberswalde, and 

 published regularly in monthly and yearly reports. From the body 

 of observations made at thirteen stations in operation since 1873, 

 Prof. Mlittrich had now made a more special investigation into the 

 influence of the forest on temperature. In order to obtain data 

 to serve as a basis for determining the influence exercised by the 

 forests on the daily march of the temperature, he had caused obser- 

 vations to be instituted in Eberswalde every two hours throughout 

 a period of fourteen days from June 15 to 30. The graphical 

 representation of these observations showed that the curve of 

 temperature for the field station, starting from the point reached at 

 midnight, sank a little at first, then rose at a quick, Ijut later on 

 at a somewhat abated, rate to its maximum at about two o'clock, 

 whence it sank again, rapidly at first, then more slowly to its 

 midnight level. The curve of temperature for the forest station 

 had, generally speaking, an analogous course. At midnight, how- 

 ever, its curve started at a higher point than that of the field 

 station, crossed the latter at 5 a.m., and afterwards continued to be 

 lower than the field curve, till at 8 p.m. it intersected the field 

 curve for the second time, and thence continued above it till 

 midnight. The difference in the maxima of the two curves was 

 considerably greater than the difference in their minima, that is to 

 say, the wood exercised during the day a more powerful cooling 



