For this shuttering we shall need a number of pieces of wood two feet long, an inch thick and three inches wide-floor boarding will do very well-these are the ' spacers.' They are pressed vertically and edgewise into the sides, so that they resemble ribs, at intervals of eighteen inches. Boards are then roughly nailed to the spacers ; plywood is the best for a circular pond, as it gives to the shape. (Figs. 5, 6 and 7.)
We now have a space between the earth and the boards of three inches, i.e., the width of the spacers. Into the space we place the cement. In a very large pond it is advisable to reinforce the cement with wire-netting, this helps to bind the cement.
The cement should be mixed on some boarding, not on the lawn or a path, and the best mixture for our purpose is in the proportion of one bucketful of cement to three of builder's sand. These ingredients should be well mixed when dry by turning frequently with a spade. The water is added slowly until the cement has the consistency of thick cream. If it is not well mixed and turned it will be porous and air bubbles will form. After it has been well turned, it is inserted in the space between the earth and the shuttering : with a stick poke the cement about and also tap the shuttering occasionally to make sure it will settle down well. As the work proceeds the spacers must be removed and cement will take their place.
If possible, each stage of the cementing should be completed in the course of a day ; if one part hardens before another, a crack may form. At night, damp sacks placed over the finished work will prevent cracking from frost or from the cement drying too quickly.
By the next day the cement will be sufficiently hard for the next stage to be started upon. This will be the shelf constituting the shallow part of the pond ; to keep the soil in, a raised ledge is necessary. The width of the shelf will depend largely on the in- dividual taste, but for a pond such as we are constructing now three feet will be admirable.