Nails for training wall trees are best made of cast iron, being the cheapest, stoutest, and most enduring. Before using they should be heated almost to redness, and then be thrown into cold linseed oil. When dry, they have a varnish upon them which preserves them from rusting, and prevents the mortar of the wall slicking to them so corrosively as it does if they are-uuoiled. In drawing old nails from walls, the mortar is not so much disturbed if the nails are driven in a little further before they are extracted. Old nails may be renovated by being heated to redness, and then thrown into water: this removes from them the mortar; and then they may be again heated and put into oil as before directed. The cast iron nails used by gardeners are known to the ironmonger as wall nails, and are described as 21/2, 3, 4, and 5 11). wall nails, accordingly as 1,000 of them are of those weights.

"Nails in most cases require to be driven only a very little way into the mortar, and walls then do not become defaced by them for many years. In all summer nailing of peach trees, roses, etc, the point only requires to be driven in, so that the nail may be easily withdrawn by the fingers. If these precautions are attended to, and the nails are not driven into the face of the bricks, but between the mortar joints, a good wall will last for half a century without requiring fresh pointing, and by nails the branches of a tree can always be better placed than by loops or similar contrivance."--Gard. Chron.