CHAPTER XV.

TEMPERATURE AS AFFECTED BY DRAINAGE.

Drainage Warms the Soil in Spring.--Heat cannot go down in Wet Land.--Drainage causes greater Deposit of Dew in Summer.--Dew warms Plants in Night, Cools them in the Morning Sun.--Drainage varies Temperature by Lessening Evaporation.--What is Evaporation.--How it produces Cold.--Drained Land Freezes Deepest, but Thaws Soonest, and the Reasons.