e separated by thawing. Winter
rye, no doubt, makes considerable growth under snow. Cultivated plants,
in general, however, do not grow at all, unless the soil be raised above
45 deg.. The sun has great power to warm dry soils, and, it is said, will
often raise their temperature to 90 deg. or 100 deg., when the air in the shade
is only 60 deg. or 70 deg.. But the sun has no such power to warm a wet soil,
and for several reasons, which are as follows:

1. _The soil is rendered cold by evaporation._ If water cannot pass
through the land by drainage, either natural or artificial, it must
escape, if at all, at the surface, by evaporation. Now, it is a fact
well known, that the heat disappears, or becomes latent, by the
conversion of water into vapor. Every child knows this, practically, at
least, who, in Winter, has washed his hands and gone out without drying
them. The same evaporation which thus affects the hands, renders the
land cold, when filled with water, every gallon of which thus carried
off requires, and actually carries off, as much heat as would raise five
and a half gallons of water from the freezing to the boiling point.

Morton, in his "Encyclopaedia of Agriculture," estimates that it would
require an expenditure of nearly 1,200 pounds of coal per day, to
evaporate artificially one half the rain which falls on an acre during
the year. In other words, about 219 tons of coals annually, would be
required for every acre of undrained land, so as to allow the free use
of the sun's rays for the legitimate purpose of growing and maturing the
crops cultivated upon it. It will not then be surprising that undrained
soils are, in the language of the farmer, "cold."

2. _Heat will not pass downward in water._ If, therefore, your soil be
saturated with water, the heat of the sun, in Spring, cannot warm it,
and your plowing and planting must be late, and your crop a failure.
Count Rumford tried many experiments to illustrate the mode of the
propagation of heat in fluids, and his conclusion, it is presumed, is
now held to be the true theory, that heat is transmitted in water only
by the motion of the particles of water; so that, if you could stop the
heated particles from rising, water could not be warmed except where it
touches the vessel containing it. Heat applied to the bottom of a vessel
of water warms the particles in contact with the vessel, and colder
particles descend, and so the whole is warmed.

Heat, applied t