292 
Yapp,— On Stratification in the Vegetation of a 
earlier part of the day, all the conditions were favourable to evaporation. 
Although the temperature was not very high, the relative humidity was low, 
the wind strong, and the duration of sunshine considerable (see Table I). 
In the course of the afternoon the wind moderated, and between 3 and 4 p.m, 
there was heavy rain for about twenty minutes ; the temperature also dropped 
Text-Fig. 5. Curves 1 of Evaporation and Temperature for July 20 and 21, and August 15, 
1907. 
suddenly. The effect of these changes on the evaporation is easily seen in 
Text-fig. 5. 
(b) Evaporation in 1908. 
Having completed many of the field observations which had taken me 
to the more distant parts of the Fen, I was, in 1908, at liberty to take more 
1 The methods used in the construction of these curves are explained on p. 319. 
