on the Climate and Agricultui-e of the British Isles. 51 
sides most exposed to his influence ; so that lines of temperature 
might be drawn on the delicately-shaded surface; and between 
night and morn the snow-cold mantle of winter is gone, and 
the emerald-green of spring returns with the thermometer 
at :){r. 
Tlie severe cold of last winter enabled me to examine the 
effects of a covering of snow on the soil and the protecting influ- 
ence it gives to the wheat-plant. To this end I placed three 
minimum thermometers (first tested by a Kew standard) as 
follows No. 1 on the surface of the grass under 4 inches of 
snow ; No. 2 in the air, an inch above the surface of the snow ; 
No. 3 four feet above the ground. During the whole of the cold 
period No. 1 remained very closely to the freezing-point, 32° ; 
No. 2 fell to 10°; No. 3 to 15°. Thus the air on the surface of 
the snow was 5° colder than 4 feet above it, and the surface of 
the soil was full 20° warmer than the surface of the snow. Thus 
a coating of only 4 inches of snow so repelled the cold that 
there was a difference of 20° between the two sides of the thin 
snow-bed : an amount of heat equal to the difference of the mean 
temperatures of January and July in Cornwall. 
We may, therefore, arrive at the conclusion that a covering 
of snow tends greatly to shelter young vegetation during periods 
of great cold, and that its beneficial effects in this respect have 
rather been underrated than otherwise. 
The steadiness of the temperature under the snow, compared 
with that of the air, further tends to protect the plants ; of 
which the sap-vessels of vegetable fibre are burst and disrupted 
by the variations of frost and thaw. If a frozen blade of wheat 
be held between the eye and the sun, the ruptured state of the 
vessels may be distinctly seen. In this respect also snow is a 
great preserver. 
It was found that the air on the upper surface of the snow at 
night was intensely cold, and when this cold is intensified by a 
wind from the north-east, cattle and sheep — especially young 
stock — exposed in the open field to its influence must suffer 
both in constitution and in weight. Heat is, to some extent, an 
equivalent for food, and an exposure to such a low temperature 
will often do more injury than many weeks of generous feeding 
will restore. Shelter should be provided by straw-yards and 
open linhays. 
The amount of damage done by the cold and snow of January 
last to the early vegetable crops of the west of Cornwall exceeded 
20,000Z. 
The three periods cf great cold in the past winter were each 
followed in the south-west of England by heavy and most de- 
E 2 
