352 WATERING. 



succulency of the leaves ; conveying manure held in suspension ; con- 

 veying matter for destroying insects, or parasitic fungi, such as the 

 mildew ; or poisoning weeds on walls or gravel- walks ; for causing 

 substances in powder to adhere to plants, as in applying sulphur and 

 other articles ; for clearing the leaves and stems of plants from dust or 

 other foreign matters ; for accelerating vegetation when the water is 

 warmer than the soil ; for retarding it when it is cooler ; for thawing 

 frozen plants ; for forming steam or dew in plant structures ; for 

 rooting cuttings of some kinds of plants ; for growing aquatics ; for 

 heating plant structures, and for supplying fountains and other 

 aquatic ornaments. Water in the form of snow, forms a valuable 

 protection to low plants when they can be covered by it, acting as a 

 non-conductor of the heat of the soil, and preventing it from escaping 

 into the atmosphere ; and water as ice is an object of the gardener's 

 care, the filling of the ice-house being generally committed to him. 



The ordinary sources from which water is obtained in gardens are 

 chiefly wells, and the collection of rain water in cisterns ; but it occa- 

 sionally happens that a natural stream passes through or near the 

 garden, or that water is conveyed to it by pipes or drains from some 

 abundant source. In whatever way water is supplied, it ought 

 always to be exposed in a pond or basin, so as to be warmed by the 

 sun to the same temperature as the surface of the soil before being 

 used ; unless indeed the object be to retard vegetation by its coldness, 

 which can very seldom be the case. Some very interesting experi- 

 ments were made by Mr. Gregor Drummond, in 1826, on the com- 

 parative effects of spring water and pond water, in lowering or raising 

 the temperature of the soil of a peach border, which it may be useful 

 to quote : 



1. "The first experiment was made on the 10th of May. At the 

 depth of 18 inches the temperature of the border was 64, and that 

 of the spring-water used 46. In twenty-four hours after, the tempe 

 rat-lire of the border was reduced to 52, or had lost 12. At the same 

 time the temperature of the soil being 64 as above, and heat of the 

 pond water 67, the soil at the close of twenty-four hours was 66, or 

 instead of losing 12 had gained 2. 



2. " June 20th the second watering was given. The temperature 

 of the border at the depth of 18 inches was now 74, and that of the 

 spring water 52. In twenty-four hours the border was reduced to 

 58, or had lost 16. 



" At the station where the pond water was used the temperature of 

 the border at the above-mentioned depth was 77, and that of the 

 water 82. In twenty-four hours the temperature of the border was 

 80, or had gained 3. 



3. " The third and last watering was performed on the 28th of 

 July. The temperature of the border at 18 inches below the surface 

 was 72, and that of the spring water 57. In twenty-four hours the 

 border was reduced to 61, or had lost 11 of temperature. At the 

 pond water station the border at the depth of 18 inches was 78, and 

 the water itself 74. In twenty-four hours the temperature of the 



