586 COTTAGE, FARM, AND VILLA ARCHITECTURE. Illy where it rests upon its bearings. It generally is placed a little inclined from the hori- zontal line ; the highest end being towards the sails. At the end, it has a kind of box, which has two mortises through it in perpendicular directions to receive the sails. At the back of one of these mortises, and on the front of the other, a projecting arm is left in the casting to receive screw bolts which hold the sails fast in the inortises. The cog- wheel, s, is fixed on by bolting its arms against a flanch cast on the vertical axis ; t is the commencement of a curved piece of timber 10 inches by 12 inches at top, and G inches by 6 inches at bottom, being the lever by which the heads of the old-fashioned mills are turned round to the wind. Attached to the lower end is a windlass, a cord from which fastened to any one of the posts that are fixed round the mill in a circle (see fig. 111.3) enables a man to move the head in the direction desired. There are also two pieces of wood affixed to the bottom of the lever by staples, made sharp at the lower end, to stick in the ground, and to steady the mill against any side-gusts. There are several plans now in use for making the head turn itself when the wind varies : this is done by having small sails at the back of the head that do not revolve while the head is in its proper position, but as soon as the wind varies, these sails are set in motion, and by machinery bring the head again into its proper direction. This is considered a great improvement ; but, as all the plans for this purpose involve much machinery, a detailed description of them is omitted, as they may be considered to come more under the control of the millwright than the Architect. Fig. 1121 is a section across the roof, showing the framing of one end of the 1121 head, where there is a door that may be opened to give light when any repairs of the machinery are going on.
