178 
E. MAWLEY-PERCOLATION OF RAIN. 
On examining the daily records I find that on twenty-two occasions 
during the three years the drainage ceased altogether through the 
two soils. On nine of these the drainage stopped on the same day 
in both gauges; on four that from the light-soil gauge stopped first; 
and on the remaining nine occasions it was that from the heavy-soil 
gauge which first came to a standstill. There are a good many 
instances when the drainage re-commenced on the same day from 
both gauges, and there are several instances when the drainage 
came first through the heavier soil, but none in which that from 
the light-soil gauge took the lead. 
The mean difference in the temperature of the two soils at one 
foot deep at 9 a.m., during the whole period of three years, is very 
slight, the heavy soil proving the colder by less than the tenth of a 
degree. On rare occasions the light-soil temperature exceeded that 
of the heavier soil by from half a degree to a whole degree, but by 
never more than this. During settled weather the differences in 
the readings of the two thermometers are very trifling, but sudden 
changes of temperature are almost invariably more quickly indicated 
by the one in the lighter than by that in the heavier soil. 
From the foregoing results the following conclusions may, I 
think, be fairly drawn :— 
1. Taking the whole year, there is greater evaporation from the 
surface of a comparatively light soil than from soil of a more 
retentive nature ; and consequently less rain passes through it than 
through the same thickness of heavier soil. 
2. The differences between the two soils as regards drainage and 
evaporation are considerably greater during the summer than during 
the winter half of a drainage-year. 
3. During dry weather the heavier soil invariably retains more 
moisture than the lighter one. 
4. The lighter soil is slightly warmer, but less equable in 
temperature than the heavier soil. 
Had the difference between the two soils been greater, the con¬ 
trast in the results would necessarily have been much more 
striking; moreover the number of flints in both soils no doubt 
tends to increase and at the same time to equalise the drainage from 
the two gauges, the heavier soil being so much more dependent on 
these stones for the ready passage of water through it than is the 
lighter soil. It should be clearly understood that the surface of 
the soil in each gauge is frequently hoed and thus kept free from 
vegetation. 
