or characteristic shape is that of a steep true cone; in Denmark, Sweden, etc., a Turk’s head or turban type was the standard; also in England, on the great tower mills. Yet in Holland, on the same type of mill, such was never used, but a distinct Dutch form of irregular shape, and almost always thatched. And in the Mediterranean countries the tops become so flattened or lowered as to in some cases almost disappear. The accompanying plate well illustrates these structural and geographical differences. While the old mills all divide into either post or tower mills, there are yet two well-defined further forms, or variations of type, that should be remarked. [Illustration: England, Turk head, brick tower mill. South of England, wood tower mill. Holland, tower mill. Holland, turntable type. France, tower mill. France, hybrid mill. Belgium, tower mill. Hungary, tower mill. Mediterranean, tower mill. Plain, post mill. Belgium, post mill. Barbadoes, tower mill. Rhode Island, wood tower mill. Long Island, wood tower mill. Sweden, wood tower mill. Turkey, stone tower mill. TYPICAL WINDMILL HEADS.] Sometimes a tower mill would be constructed on a circular [Illustration: TYPICAL WINDMILL ARMS. Usual canvas covered sweep. England, Bywater’s rolling canvas. England, Cubit’s patent shutter. England, Meikle’s spring sweep. England, double shutter. France, double sweep. France, folding sweep. Primitive sweep, interlaced boards. Mediterranean, double sweep canvas. Mediterranean, flying jib; Greece, Turkey, etc.] timber framework or base, carried on rollers or iron balls, forming a large turntable, enabling the turning of the entire edifice to the wind, as need be, the same as a locomotive turntable or a rotary drawbridge is turned. This therefore parallels the post mill type, in which the entire structure is turned to follow the wind, but turning on this turntable base instead of a post. This form was extensively used in the saw mill and lumber districts of Holland. The other variation is what may be called a hybrid form--part post type, part tower type. In this the contained machinery is fixed in the base, and does not rotate, being thus of the tower mill design; while in the upper part of the mill a rectangular wood housing, like a post mill, is pivoted and revolves with a tail beam, as in the post design. Such hybrid forms are found in Holland and in the valley of the Loire, at Saumur, Chinon, etc. (_B_) _The Sweeps._--With mills built for centuries and by all countries, it is but natural to expect to find a wide range of form in this most characteristic part of a windmill--the sweeps or vanes; and in this one is not disappointed.