The composition--which is something more than the old-time glue and molasses--is prepared for pouring by melting in a double-jacketed steam kettle, the stirring being done by a mixer run by steam power. When ready, the composition is drawn off from the bottom of the cooking kettles into pouring kettles which have air-tight hoods. To these a hose is attached, the other end of the hose being connected with a tank which is charged with air by a pump. The hose being then attached to the cylinder, the air is introduced from the tank into the pouring kettle, forcing the composition upward into the cylinder, and all air from the moulds. This insures a perfect roller.
When the composition has reached the top of the roller stocks, the valve at the bottom of the cylinder is closed, and the process is continued to the next cylinder ready for pouring. The cooling of the cylinders is effected by turning the cold water current around them, and a nest of moulds may be filled and emptied four or five times a day. After the cooling, the bottom plate of the cylinder is removed; the rollers drop out, are trimmed, and are ready for the shipping box.
It is only in comparatively modern times that the art of illustration has received the encouragement that makes for perfection. For this, the cheapening of the manufacturing cost in printing is mainly responsible. An illustration proper should always accompany text and in days past the making of a book was so costly in itself that the possibility of illustration was almost beyond thought. Only the wealthy could afford illustrated books and as their reading was very limited, naturally illustration was crowded to the wall. Those with money to spend on pictures preferred decorations or portraits, consequently the endeavors of artists were aimed at supplying what suited the tastes of buyers. Illustration is and always has been the art of the people. It makes clearer to the imagination their stories and their songs, it mirrors their manner of life, interests, and pursuits in a way that brightens what would otherwise often be commonplace.
Art seems to entwine itself about the strongest figures in a community, absorbing with its nourishment the ethical qualities of the leader. Thus we have Michael Angelo in a community ruled by the church, creating, at its demands, a "Day of Judgment," a "Magdalen at the Cross," a "Moses," and Velasquez, evolving a marvellous technique while immortalizing in wonderful portraits the vanity of his Spanish lords.