84 ROCK GARDENING FOR AMATEURS 



About six inches of the concrete is laid, and carefully 

 plastered over with a good coating of cement and sand ; 

 about two parts of the latter to one of cement. The 

 whole ought then to be washed over with pure cement 

 and water, as thickly as it can be applied with a white- 

 wash brush. The cement is rendered quite watertight 

 if about 10 per cent, of oil is added to the cement coating 

 and wash. The writer uses boiled linseed oil. This 

 is mixed with the cement after it has undergone its usual 

 mixing with water. The " shelf " already mentioned is 

 coated at the same time. Before the final coat of cement 

 is added, if the concrete beneath appears smooth, it 

 should be roughened before it is dry by drawing a rake, 

 or something of that kind, over it. This will cause the 

 final coating to adhere better. 



Should the pond be composed of brickwork set in 

 cement it is hardly necessary to coat it with concrete, 

 though it is wise to do so as a precaution against leakage. 

 A piece of piping should be put into the pond close to 

 the bottom, and connected with a drain. This can be 

 stopped with a plug, and supplies a ready method of 

 emptying the pond for cleaning or other purposes. 



It is always wise to test the pond before putting 

 in the soil, and it is prudent to fill it with water a day 

 or two after the cementing is completed. Should there 

 be no signs of leakage the water should be let off and the 

 soil put in position. Should there be leakage, the water 

 must be run away and an additional coating of thin 

 cement, with oil added, washed carefully over the whole 



