Book IV. CARRYING DEStGNS INTO' EXECUTION. 



381 



The last mode is the most simple of execution ; but if the great body of loose 

 materials are of a sandy or porous nature, the former will be found the safest ; either 

 however, well executed, will suffice ; and in this point of practice, execution is certainly, 

 of more consequence than design. 



1951. The sluice is the stopper or valve to a drain {fig' 370. e), carried through 

 the bank of a piece of artificial water at the lowest part of its bed, in order to be able 

 to empty it at pleasure. There are various kinds, from the simple tube and stopper 

 {fig- "71. a), to the plank-sluice (c), or grooved frame (6). This last is formed of a plate 

 of boards, generally two or three feet wide, and six or eight feet high, attached to a stalk, 

 and worked by means of a pinion and rachet in a frame of timber. The sluice is built 

 vertically into the drain as a damper is into a flue, and the length of the stalk and frame 

 is always such as to reach somewhat above the ground's surface for conveniency of work- 

 ing. 'ITie grand object as to tlie sluice is to construct it so as to admit the least possible 

 escape of water. This will generally be best attained by forming the tunnel, in which 

 the sluice is to be built, in the solid ground at the side of the head, and not in the new 

 and loose eartli, building it of masonry or brick set in cement, claying it completely on 

 all sides, and fitting in the sluice with the greatest nicety. 



1952. Syphon sluice. As it is practically impossible to form sluices and drains that 

 do not lose more or less water, owdng to the great pressure of the volume in the lake or 

 pond, it is better, where the supply is very limited, to have no drain or sluice, and to draw 

 off the water when required by a large syphon, which may easily be formed of boards ; or 

 a drain may be formed, and, instead of a sluice, a well of clay adopted as a stopper. Tlie 

 power of drawing off the water is seldom 

 used, and, unless in fishponds, or where 

 frequent clearing is necessary, sluices are 

 of little use. The superfluous water 

 which escapes over the head when abund- 

 ant, may form a cascade or waterfall ; but 

 where the waste is small, it may escape 

 at one side {fig. Si i. a) as a small gur- 

 gling rill over a bed formed of well- 

 worked clay, to prevent its working out 

 hollows, and covered by gravel, stones, 

 &C-, to give it a clear and natural-like ap- 

 pearance. As the head is generally a 

 straight mound, destitute of natural 

 beauty, it should be disguised by small 

 islands {fig. 372. h, c), or varied by plant- 

 ing on the margin, or both ; but as our 

 present business is merely to describe the 

 operations requisite to the formation of 

 pieces of water, we must refer, for what 

 concerns it as a material of landscape, to Landscape-gardening. (Part III. Book IV.) 



1953. Sm faces to imitate nature, such as hills, knolls, and all the variety of raised 

 surfaces in pleasure-grounds, are formed by heaping up materials in the indicated shapes ; 

 and hollows of equal variety, by hollowing them out ; in both cases, studying to keep the 

 best earth at the surface, and so to blend the forms with those to whidi they are united, 

 that no line of demarcation may ever afterwards be discoverable. 



1954. Surfaces avowedly artificial, as levels, terraces, slopes, banks, beds of earth, or 

 dung-beds, being once distinctly marked out, are executed with equal facility and greater 

 certainty of attaining the end or effect. Formerly the geometric style of gardening af- 

 forded an ample field for the exercise of this class of operations ; but at present they are 

 chiefly confined to the kitchen-garden, the sites of buildings, and a linaittnl space around 



