The construction of the box-frame spring mattress requires sides about 6 in. high with 8 laths across the bottom, and 5 10-in. springs for each lath in a mattress 4 1/2 ft. wide, the latter being secured to the laths by small staples, tied down in a somewhat rounding form, and finally lashed each way. The springs are covered with strong canvas firmly sewn on as in the case of a single chair (p. 401); and a well-stitched roll 3 or 4 in. high is fixed round the box. On to the canvas is picked the hair or wool stuffing (20 lb. of the former or 25 lb. of the latter), and this is covered by ticking, laid with the stripe running lengthways, and lightly tacked; next the tick is tufted, and the whole is turned upside down, the tick being tacked on to the bottom edge of the box. Double webbing is nailed on the under side about 12 in. from the corners, for handles, and the under side is finally covered with canvas. When the mattress is made in two halves, the sides of each spring box will only bo half the length of the bed; the two middle rows of springs should almost meet, and a strip of cane lashed across the ends of the half boxes where they join preserves the squareness of the boxes and constitutes a base to work upon, but it must be stitched up all round, keeping the middle soft.