378 METEOROLOGY. [IIaech 



influence than it exerted a warming influence during the night. 

 The maximum of the forest curve, besides, occurred from half an 

 hour to an liour later than that of the field curve. For the further 

 study of the influence of forests on temperature, the data of the 

 maximum and minimum thermometers were utilized. From these 

 were calculated the daily variations of temperature for the different 

 months at the difl'erent stations, and the yearly course of these 

 variations for each particular field and forest station was exhibited 

 by a curve, the abscissa3 of which were the months and their 

 ordinates the mean daily oscillations of temperature. From the 

 curves of the various stations, special curves for the open field, the 

 fir, pine, and beech forests were next deduced. The curve for the 

 field station showed that the daily variations in January and 

 February were within narrow limits and pretty similar, that in 

 March the curve rose, then mounted very rapidly in spring and up 

 to its summer maximum, whence in September it dropped very 

 rapidly, abating, however, its rate of faU in October, and then 

 creeping down very slowly through November and December. The 

 curve for the fir forest was, in January and February, not much 

 different from the foregoing in the same months, but the variations 

 were smaller than in the case of the field station. The curve 

 next rose rather more steeply on to the month of May, and after 

 that proceeded more slowly towards its summer maximum, from 

 which it fell, at first quickly and then slowly. All along, however, 

 it kept inferior to the curve of the field station, the interval between 

 the two being much greater in summer than in winter. In the 

 pine forest the curve marking the variations of temperature showed 

 a similar course, except that from January to April it approached 

 much nearer the curve of the field station than did the curve of 

 the fir forest, while in summer, on the other hand, it kept at a 

 greater distance from that of the field station, but joined the fir- 

 forest curve in autumn. Thus the curve of the pine forest likewise 

 all along kept below that of the field station. The difference 

 between them was less in winter, and in summer it was almost 

 just as great as the difference between the field curve and the 

 fir-forest curve. Altosether different, however, was the curve of 

 temperature and its variations in the beech forest. In January 

 and February it lay at but a very little interval below that of the 

 field station, came up almost quite level with it in spring, or even 

 shot just a very little beyond it, attained its maximum for the year 

 in May, whence it at first rather slowly, but afterwards very 

 rapidly, declined. In the beech forest, therefore, after it put on 

 its full foliage in May, the variations of temperature lowered con- 

 siderably, showing a very wide difference throughout the mouths of 



