That, as to their Height, regard must be had to the Nature of the Soil,
in its difficult Admission of Water; for the greater that is, the
greater Declivities the Ridges should have; and then, if the Soil be
not deep, they should generally be made the narrower.
There is one thing which Mr. _Bradley_ takes no notice of; _viz._ That
no more of the Rain, or other Benefits of the Atmosphere, which descend
perpendicularly, can fall on an Hill, or on a Ridge, than what would
fall on the Base, or Ground-plot. But ’tis probable, that more of
the fine Vapour, which swims in the Current of the Air horizontally,
does strike and break against those Eminences, and so make an
Equivalent[224], except that it runs off more quickly.
[224] But though Ridges do alter or increase the Surface, the
Quantity of Soil or Earth remaining the same as on the Level, and
of no greater Depth than can be tilled, it may produce equal Crops
of Corn with the Level, and no more; except from the Advantage the
Ridges may give it in lying drier.
Notwithstanding all I have here said, in behalf of Ridges, I must
confess, that, for my Hoeing-Husbandry, I should prefer Land that is
naturally dry enough, without a Necessity of being laid up in any
larger or higher Ridges than what may contain Six Feet in Breadth[225],
that Size being the largest that is proper for the regular Operation of
the Horse-hoe.
[225] Since the Printing of my Essay, I find, upon Trial, that these
narrow Ridges are as effectual as any for carrying the Water off from
my clayey Hill; and that they be made much less horizontal than broad
Ridges, whereby their Furrows are the more easily turned upwards
against the Declivity.
I have not tried any narrower Ridge than that of Six Feet upon this
Hill: But I have had full Experience of Five-feet and of Four-feet
Ridges upon other Land; and find that all Sizes of these narrow
Ridges are very advantageous, even where the Crop is to be sown upon
the Level; for fewer Furrows are necessary for the Tilling of an
Acre, when ’tis kept in such Ridges, than in broad Lands; and after
wet Weather the Ridges will be fit to be plowed much sooner than
level Ground.