for Twenty Years in succession on the same Land. 141 
disintegration, and porosity of the subsoil, and retention of 
moisture by it ; the combined conditions leading to a corre- 
spondingly greater distribution of the roots in the lower layers, 
bv virtue of which the plants would obtain possession of a 
greater range of soil, and an increased supply of moisture within 
it. In the one case, therefore, it was the resources of moisture 
in the upper layers of the soil, and in the other those in the 
lower layers, that rendered the growing crop more independent 
of the supplies from external sources. 
In conclusion, the difference of effect of the excessive summer 
heat and drought on winter and spring-sown crops, and on crops 
grown on deep and on shallow soils, was very striking. Thus, 
the experimental wheat-crop indicated a produce about 20 per 
cent, over the average, and the wheat-crop of the country at 
large was extremely good on good soils, though very poor on 
poor soils, yet was supposed to yield in the aggregate 20 per 
cent, over an average. The rather late-sown experimental barley, 
on the other hand, gave a produce from one-tenth to one-third 
below the average, according to the manure employed ; and the 
barley-crop of the country was good when sown early on deep 
soils, and very deficient when sown late on shallow soils, but 
gave in the aggregate a considerably deficient crop. The great 
protection against the injurious effects of summer drought, which 
the early sowing of spring-crops gives, by enabling the plant to 
obtain possession of a more extended root-range, was thus, in this 
season, strikingly illustrated. 
Eighteenth Season, 1869. 
The extraordinarily warm period of nearly nine months' dura- 
tion ended with September, 1868. October and November were 
throughout, with very few exceptions, colder than usual, both 
day and night ; whilst in October there was a deficiency of rain, 
and in November a very great deficiency. December, on the 
other hand, was almost throughout very much warmer than 
the average, with a very great excess of rain, some violent gales 
of wind, very variable, but, upon the whole, very low barometric 
pressures, and high degree of humiditv of the atmosphere. The 
average temperature of December had, indeed, been exceeded 
only twice during the preceding ninety-eight years ; namely, 
in 1806 and 1852. With the exception of a week after the 
middle of January (1869), the very warm period continued until 
the end of February, completing three winter months of average 
temperature about 6 degrees higher than the average of ninetv- 
eight years. There was, again, considerable excess of rain in 
January, and a slight excess in February. March, on the con- 
