All the surfaces of the grounds, canvas, panels, millboards or paper are prepared in a similar way. The preparation of the canvas particularly occupies much time, and is carefully manipulated in order to render it smooth and pliable. The English prepared canvas is much preferable to the foreign, because the English is generally prepared solely by hand and much of the foreign is coated by machinery. Hand-prepared canvas is stretched to its utmost tension, and prepared in this state it will not give to any appreciable extent afterwards; but machine-prepared canvas cannot be coated whilst the cloth is in a state of tension, the consequences is that the cloth will afterwards still stretch considerably, and the surface not being equally elastic is liable to crack. For large sizes canvas is the only available ground, in fact it is manufactured by Messrs. Reeves in pieces without a join as large as 13 feet by 20 feet. ,