324 MR. В. S. ADAMSON : АХ ECOLOGICAL STUDY 
To obtain a record of the variations of evaporation throughout the growing 
season а permanent set of instruments was set up near the centre of the 
wood. The shrubs in this part were not quite half-grown, being about 8 ft. 
high, and just about to form а closed canopy. The ground flora was mainly 
Spirea Ulmaria. А vertical series of evaporimeters was arranged, the top 
one, Ej, being just clear of the shrub layer: the second, B, was put at the 
level of the densest shrub foliage; while the third, Ёз, was at the summit 
level of the ground flora. It was not found practicable at first to have a 
permanent instrument on the ground, owing to the herbage getting trampled 
down all round, and artificial conditions so produced. А fourth permanent 
instrument, E4, was placed in another part, just clear of the ground flora ; 
here the wood was fairly open, there being no shrubs or trees within several 
yards, 
For the season these instruments gave the following results for evaporations 
for intervals of a week, measured in cubie centimetres :— 
Week ending E. | E.. | E. E, 
Feb. 21............ 2ш .. DII 
Mar. 1............ 54 | | 
| Mar. И......... ... 88 | 98 | 78 | 
Маг. 15...... TM 42 45 | | 
Apr. 20....... ..... 86 60 | 
Apr. 27...... ees 147 122 | 126 145 
May 4.......... .. 141 | 112 | 115 124 
Мауи 14 — | 09 | 18M 145 
| May 18............ 182 149 | 142 176 
| May 35.......... .. 177 147 | 140 166 | 
(June. 1............ | 125 108 107 134 
June 8.......... .. 141 91 93 125 | 
June 15............ 114 66 13 91 | 
June 25..........., 167 .. 131 159 
Aug. 17............ 121 8t 62 
These figures show a maximum of evaporation for a week occurring about 
the middle of May ; this is before the full foliage of the summer is formed, 
and although the top instrument, Ej, may later reach figures almost as great, 
the others never do. 
In this wood the rate of. evaporation does not rise evenly with the height 
above the ground, as might have been expected ў. Thus, E; frequently gives 
smaller rates of evaporation than Es, owing to the fact that the stratification 
of the vegetation is uneven ; and E; comes between two layers, and, con- 
sequently, is rather more exposed than E», which is in the midst of the second 
* Corrected readings after calibration on methods suggested by Yapp, 1909, p. 311. 
T Fractions are here omitted. | СХ. Yapp, 1909, p. 29]. 
