190 THE VILLA GARDENER. 



285. With a view to health, water ought never to be introduced where it will 

 increase, in any sensible degree, the quantity of moisture that would other- 

 wise be taken up by the atmosphere of the locality, either in summer or 

 winter. From this principle the following rules may be deduced : 



1. That the surface to he covered with an artificial piece of water should he small, in 

 proportion as the general surface of tlie ground is flat ; the soil retentive ; the park, 

 pleasure-ground, or enclosure, small ; and the trees and shnihs numerous. 



2. That the most wholesome situations in which artificial water can be introduced, are 

 those where the general surface of the ground is elevated, and the soil naturally dry, and 

 not thickly covered with trees and shrubs. 



3. That, in flat situations with retentive soils, where the surface is thickly planted with 

 trees or shrubs, water, even on the most limited scale, should never be introduced, with- 

 out, at the same time, rendering the surface of the surrounding ground perfectly dry by the 

 frequent drain system. 



4. That in no description of artificial water ought the decay of vegetables to be allowed 

 to take place, and more especially along the margin. 



5. Tliat the margin of all artificial pieces of water ought to be formed of a considerable 

 tliickness of gravel or small stones, or of blocks of stone, in imitation of rockwork ; in order 

 to diminish the quantity of spongy or marshy matter, by which evaporation never ceases ; 

 and substitute for it a smooth hard surface, from which evaporation will go on with rapidity, 

 and which will tlms soon become quite dry. 



Gardeners are in the habit, when they plant out pelargoniums, and other spongy-wooded 

 green-house plants, on lawns, to reduce them before planting out to single stems, and to free 

 these from leaves to the height of 3 or 4 inches. After planting, the surface (which forms a 

 very gentle knoll, about 1 ft. in diameter, and, say, from 1 in. to 2 in. high in the centre, 

 where the stem is placed) is bedded over with small pebbles, about the size of pigeons' eggs ; 

 and these, by drying rapidly after rains, prevent the damp from lodging about the collars of 

 the plants, which, without this precaution, would, as it is technically called, damp off. Now, 

 if gardeners would apply the rationale of this practice to the margins of basins, ponds, lakes, 

 rivers, and all pieces of water whatever, natural or artificial, in pleasure-grounds, they would 

 render the evaporation from these pieces of water wholly innoxious. The evaporation from 

 clear water is simply injiu-ious by increasing the quantity of moisture held in suspension by 

 the atmosphere ; but the evaporation from water containing a mixture of decaying vege- 

 tables from the park above it, contains, in addition to water, those deleterious gases known 

 as malaria. As all pieces of water are liable to rise or fall with rains or great droughts, the 

 breadth and height of the space along their margins, which is gravelled or covered with 

 stones, ought to be such as that, in the greatest drought of summer, when the water is sunk 

 to the lowest point, it should not expose any of its earthy bed to the air ; and that, in 

 spring and autumn, when it is raised to its greatest height by rains, it should not touch the 

 leaves of the plants along its margin. This is the beau ideal mode, of treating artificial 

 water, where the object is to render it wholesome ; and it is gratifying to find that it is as 

 superior to the common mode of treating the margins of pieces of water, in its accordance 

 with the principles of picturesque beauty, as it is with the principles of health. 



6. That, in distributing the trees and shrubs over a park or pleasure-ground containing a 

 piece of water, provision should always be made for the exit from the grounds of the vapours 

 which arise from the watery surface. This is to be done by broad spaces of lawn or turf 

 without trees, extencUng from one or from both ends of the piece of water, through the 

 park or pleasure-ground, to ground on a lower level (see Jig. 91).), where the air charged 

 with vapour will find its way by its own gravity. Where this is neglected, parks in low 

 moist situations, with trees scattered regularly over their surface, become covered with 

 what may be described as one general pond of malarian vapour ; or with a number of 

 ponds, in which the vapour is dammed up by trees crossing the course which it would 

 naturally take along the lowest level. The gardens of the New Palace at Pimhco may be 

 considered as one immense pond of malarian vapour, confined by the palace and other 

 buildings at the lower end, and by high walls along the sides ; and which is prevented from» 

 being dispersed by winds or the sun, by the groups of trees, moimds, grassy banks, &c., 

 contained in the interior. 



