42 THE ART AND PRACTICE OF LANDSCAPE GARDENING. 



for producing effect, or promoting the growth of plants, but for 

 hiding boundaries or masking unsightly objects that are irremovable. 

 Ground that is taken near at hand is most convenient, and it is 

 cheaper to work it by barrows than to bring it a distance in carts. 

 Such earth may be obtained from the foundations of the building ; 

 by lowering the ground at foot of the terrace ; by making the lawn at 

 lower level ; by lowering the surface between trees or places intended 

 for single plants, or between larger groups ; by removing ridges ; 

 by making hollow sunk panels, descending rose gardens ; by lower- 

 ing the lines of walks in certain places, so that these, in addition to 

 providing such required earth, may add, by their undulating gradient, 

 to the beauty of the landscape. Top soil should always be spared, 

 and subsoil used for general filling, and this last so arranged that 

 2 ft. of top soil should be available for the planting area. 



In lowering a lawn say i ft. the method of work should 

 be what is termed back-handed ; that is to say, the top soil of a 

 narrow strip across a given area should be taken off and laid aside ; 

 then a foot deep of the underlying soil should be taken out and 

 wheeled to the required place of deposit ; then a similar strip 

 should, in like manner, have the topmost foot of earth taken off 

 and cast on the already lowered first strip, the new surface of which 

 being first broken up ; this operation being repeated with each 

 succeeding strip of the space, till the last is reached, when the 

 top soil laid aside from the first division can be deposited to make 

 good the surface. The earth thus gained remains for use. 



One inch of rainfall per acre gives 101 tons or 3,630 cubic ft. 

 of water, which would fill a tank 30 ft. by 12 ft. by 10 ft., yielding 

 2% cubic ft., or 15^ gallons per minute, if the rainfall continue 

 24 hours. The annual rainfall in London averages 26 in., and it is 

 reckoned that two-fifths of it percolates into the soil. It is by access 

 of oxygen conveyed by water that plant growth is stimulated, and 



