38 FOREST INFLUENCES. 



daily observati©iis sliould be taken. A long discussion followed on Dr. 

 Libnrnau's recomniendation of Piclie's evaporometer. It was stated 

 that tlie observations gave no means of comparison with actual natural 

 processes, that the readings of the instruments were untrustworthy 

 and the errors hard to correct, that it was desirable to follow more ex- 

 actly the processes of nature, that it is not possible to find an instru- 

 ment fulfilling all necessary conditions, and that on this account the 

 Italian service had rejected all evaporometers. The conference finally 

 decided that, while observations of evaporation were important, there 

 is no form of measuring instrument which can be especially recom- 

 mended. An instrument should be invented which would permit the 

 measurement of evaporation from a free water surface and also from 

 soils of different characters. Provisionally observations should be 

 carried on with the weighing instruments and with Cantoni's modifica- 

 tion of Piche's instrument. 



Clouds should be observed; fog should be recorded when it covers 

 the station and its density should be given on a predetermined scale. 

 Herr Friesenhoff recommended a measurer of dew depending on the 

 power of rock salt to appropriate atmospheric water. Drs. Neumayer 

 and Ebermayer expressed the opinion that balance drosometers should 

 be tried. They should have larger dimensions (2 feet square or more) 

 which should be filled with different materials. The conference com- 

 mended the subject of a good measurer of dew as a jjroper subject of 

 study. The measurer of precijiitation should be on the model recom- 

 mended by the International Congress and Committee. The seepage 

 of ground water is important, but the so-called Ijsimeter is not to be 

 recommended. Wind observations should be taken, as at ordiuarj^ sta- 

 tions. 



The system of parallel stations, already ado])ted in Bavaria, Switzer- 

 land, and at the other German stations, was especially commended, 

 lladial stations were commended tor the broader fields of observation, 

 and it was recommended that a series of such stations should be 

 established in eastern Germany and in Austria Hungary, and the 

 final recommendation was made that observations should be made at 

 the forest station of each radial system, directly over the crown of tlie 

 trees. Thus this happy method, the fundamental importance of which 

 makes it strange that it was not employed from the first, reached at 

 least the stage of recommendation for general use. The practical ditfi- 

 culty of its use is probably what has prevented its adoption. This could 

 be easily overcome by the use of registering instruments which are 

 made to run for fifteen days without attention, or by the use of the now 

 excellent instruments for electric registry at a distance. 



To the proposal of the first meteorological congress for replies as to 

 what could best be done, Dr. Woeikoff made a suggestion which was 

 not taken into consideration by the conference. He proposed India as 

 the best field for such studies, especially with reference to rainfall. 



