To permit the workman to swing the mass of glass out conveniently to the full length of the intended cylinder, a long, narrow pit or trench is provided below the floor level, and by standing alongside this trench the workman is enabled to swing the glass within the trench at arm’s length until the requisite length and width of cylinder are obtained. This work requires a high degree of skill and strength. The shape of the cylinder of glass is now as shown on page 91 (_d_). The extremity of this cylinder is now re-heated and opened with the aid of a spring tool with charred wooden prongs, until the opening is enlarged and drawn out to the same diameter as it is throughout the cylinder. It is now in the form of an open-ended cylinder (_e_). The cap of the cylinder at the blow-iron end is now cracked off. A thread of hot glass is wrapped round the shoulder near the cap, and the line chilled by using a curved, hook-shaped rod of iron. Whilst the cap is being cracked off, the cylinder is allowed to rest supported by a wooden cradle. The cylinder is now open at both ends (_f_) and is taken to the flattening kiln or furnace. This kiln has a level, smooth floor, heated from below, upon which the cylinders are flattened out. Placing the cylinder on the floor in front of him, the workman places along the inside length of the cylinder a long red-hot iron rod touching the glass, and then chills the line with a touch from a cold iron rod. This causes a split to take place along the whole length of the cylinder. As these cylinders are split open, they are removed to a hotter zone within the flattening kiln, where the heat causes the cylinder to uncurl and gradually flatten out. As the sheet becomes flat the workman levels it out with a flat block of charred wood called a polisher. This is attached to a long handle, and is rubbed over the face of the sheet of glass. The weight of the wooden block is just sufficient to smooth out any creases and assists in levelling out any irregularities of the surface. It is essential that the floor upon which the glass is resting should be perfectly smooth and level, and uniformly heated. As each sheet is levelled, it is removed to the annealing oven and afterwards stacked up until cool, after which the rectangular sheets are cut up to the various sizes required for window panes. It is evident that the crown glass method gives more waste in cutting up, and does not provide such large sheets as the cylinder method. On the other hand, cylinder glass always shows a certain amount of waviness on the surface, and is not so brilliant as crown glass. The better surface of crown glass no doubt is due to the fire-polishing it receives when being expanded out into the disc. It appears to be somewhat difficult to get a perfectly smooth level face to cylinder glass by using the wooden polisher.