62] A TOPOGRAPHICAL 



cess. After boring through a clayey stratum into one of gravel 

 beneath, the water has been known to rise in a constant stream up 

 the hole, and thus to drain considerable breadths of land above 

 which the water had injured it for want of a vent, which is now 

 given along the bottom of the hollow drain. 



2. Irrigation,, or the watering of land, is a very important part of 

 agriculture, the advantages of which are generally admitted, and 

 well known by all intelligent farmers ; but it is by no means carried 

 to the extent of which it is capable. The omission is in part owing 

 to the jealousy of millers and others interested in the streams. The 

 industry of many individuals has, however, been successfully ex- 

 erted in this valuable species of improvement. 



Respecting a system for irrigation, no general one can apply to 

 particular cases ; but in all cases where a stream naturally falls 

 down a valley, and the sides of such valley consist of easy and 

 regular declivities, the best way undoubtedly is to draw the water 

 nearly upon a level along a main carrier, as far as it is intended to 

 use it, this water to be let out of the said main carrier at pleasure 

 by sluices constructed in different places in its sides, into floating- 

 gutters, such floating gutters being cut nearly on a level along 

 the sides of the declivities, one below another. These floating- 

 gutters marked out by a level, will collect the water from the spaces 

 of land above them, and deliver it upon the spaces below with a 

 little attendance and attention. The land should be watered in 

 rotation, different parts successively, and not too long in a place : 

 the gutters will require an annual cleansing or scouring out, other- 

 wise they will choke up with grass. 



Watering will not have the same good effect upon all soils : it 

 makes the greatest improvement upon warm soils, but on strong 

 cold clay it should be used sparingly ; and every one knows the 

 necessity of draining the land properly previous to watering. 



Reservoirs. The greatest benefit would be derived from watering 

 in dry seasons, when all kinds of land would be most improved by 

 it. This might be effected by reservoirs constructed in valleys, to 

 retain the water of rainy seasons, or violent showers ; and however 

 visionary the idea may appear, it is economically practicable where 

 the fall is not already occupied by mills or public works. A reser- 

 voir of a few acres might be constructed at the head of a vale on 

 entering an estate, at (in general) less than twenty pounds per 

 acre, to receive violent rains, or the melting of snow ; the usual 

 current, if such there be, might pass along side it in common, if 



