The general design of the sink and its equipment is shown in Fig. 11.  For the uprights, which rest on the beading of the washstand, use two boards 9 inches wide, 1/2 inch (actual) thick, and 36 inches long.  The top shelf, to carry the pail or other water container, should be of 1-inch stuff; and the two lower shelves be not more than 5 inches wide and 3/4 inch thick.  Space the shelves at least 11 inches apart, so that they may accommodate tall bottles.  The superstructure will gain in rigidity if the intermediate shelves are screwed to the uprights, in addition to being supported on ledges as indicated; and if the back is boarded over for at least half its height, there will be no danger of sideways collapse, when a full bucket is put in position.

The top of the washstand, on which the developing will be done, must be provided with a tray of lead or zinc.  Lead is preferable, as lying flatter; but the jointing at the corners is more difficult than the soldering of sheet zinc, which, though more liable to chemical corrosion, is much lighter than the thinnest lead—­weighing about 1-1/2 lbs. to the square foot—­that could well be used.  If lead is selected, the services of a plumber had better be secured, if the reader has had no experience in “wiping a joint.”

A zinc tray is prepared by cutting out of a single sheet a piece of the shape shown in Fig. 12.  The dimensions between the bending lines (dotted) are 1/8 inch less in both directions than those of the shelf.  The turn-ups a, a, b, b, should not be less than 1-1/2 inches wide.  Allow half an inch at each end of b b for the turnover c.  Turn a a up first, then b b, and finally bend c c round the back of a a, to which they are soldered.  A drop of solder will be needed in each corner to make it water-tight.  When turning up a side use a piece of square-cornered metal or wood as mould, and make the angles as clean as possible, especially near the joints.

[Illustration:  Fig. 12.—­Showing how the tray for sink is marked out.]

A drain hole, an inch or so in diameter, is cut in the centre of the tray.  To prevent the hands being injured by the tray, the front should be covered by a 1/2-inch strip of zinc doubled lengthwise, or be made a bit deeper than 1-1/2 inches in the first instance and turned over on itself.

Before the tray is put in position the basin hole must be filled in, except for an opening to take the waste pipe.  The plug is pad-sawed out of wood of the same thickness as the top, to which it is attached by crossbars on the under side.  The whole of the woodwork, or at least those parts which are most likely to get wetted, should then be given a coat or two of paint.

A waste pipe, somewhat larger than the drain hole and 3 inches long, having been firmly soldered to the tray, beat the edges of the hole down into the pipe.  Then prepare a wooden collar to fit the pipe outside, and drill a hole on the centre line to take a carpenter’s screw.  If the edges of the tray are supported on slats 3/16 to 1/4 inch thick, and its centre is kept in contact with the wood by the collar pressing against the underside of the shelf, any water will naturally gravitate to the centre and escape by the waste pipe.  This automatic clearance of “slops” is a very desirable feature of a developing sink.