This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
This method is principally used upon large stocks or on the branches of old trees. The stock is first cut off at a point where it is desirable to insert the cion; it is then split with a large knife or chisel - being careful to divide the bark, at the same time leaving its edges smooth. When the knife is withdrawn, an iron or hard wood wedge is inserted in the center, or at one side of the stock, as shown in fig. 5; the cion is then cut in the form of a wedge (5), and fitted into the cleft (c), fig. 6; the wedge is then withdrawn, and the elasticity of the stock will hold it in its place. Grafting-wax is then wrapped around the stock, entirely covering the wound. When the stock is an inch or more in diameter, two cions may be inserted, one on each side - the operator being careful to place the external surface of the wood, not bark, of both cions and stock exactly even; at least they should meet at some one point; and to make sure of this, the grafts are set inclining inward, as shown in fig 7 - a, the upper portion of the cion; &, the lower end. The cion may be two or three inches long, containing one or more buds. Fig. 8 shows a cross section of the stock and cion inserted.
The bark on the cion, as will be observed, is much thinner than that on the stock; but this is of no consequence, provided the edges of the wood are even.