THE outer shells of hotbed and cold-frame are identical, and can be made by any handy man. As all sashes are made in one size—namely, six by three—the boxes must correspond; to insure water running off and all the power of the sun being utilised, they must slope lengthways, the top end of a box being three or four inches higher than the bottom. The ordinary box or bed frame is made six feet long, three feet wide and fifteen inches high at the top end, sloping to twelve at the foot, and stands on the surface of the ground, but the plan ............