THE NEW WATER-GARDENING 237 



seven or eight inches. It is wise to carry it two or three 

 inches above the ground-level, so that soil may not be 

 constantly crumbling over. There will be no stiffness if 

 appropriate plants are put outside. To provide moisture 

 for these, small holes may be left in the concrete at inter- 

 vals, just below the surface of the water, in order to 

 allow a little to drain through. 



When the concrete has set quite hard excavation may 

 proceed. It is wise to find a use for the soil which has to 

 be removed before shifting begins, so that there may be 

 no waste or delay. In some cases it will be required for 

 modifying the slope of the bank or altering the outline of 

 a hollow, and then the cost of shifting will be slight, as it 

 can be done with a wheelbarrow. The basin should be 

 made rather deeper at the centre than at the sides, but 

 it is neither necessary nor desirable to go deeper than 

 three feet. There may be a gradual rise from the centre 

 to the concrete shell at the margin. The whole of the 

 bed should be concreted if the soil is porous, and this is 

 not such a serious matter as an inexperienced person 

 might suppose, because a large quantity of concrete can 

 be made in a few minutes by mixing six parts of cinders 

 and one of quicklime with a little cement and water. It 

 can be shovelled on and levelled quickly. Indeed, con- 

 creting is a much more simple operation than puddling, 

 for to make a pool thoroughly water-tight with puddled 

 clay the latter wants chopping up, kneading into a mass 

 with water and well ramming. Even then it is not 

 always satisfactory. Six inches of concrete will render a 

 pool quite secure so long as it is spread on a firm, smooth 

 bed of soil, but as an extra precaution an inch or two of 

 fine concrete may be spread on the top, and the whole 

 allowed to set well. 



There should be two openings in the concrete large 



