Windmill

a machine turned by the power of the wind, which is caused to act upon vanes or sails, and give them a rotary motion. The external structure of the common windmill is well known to every person, but the interior mechanism not being so generally understood, we have given (in plate 175) a vertical section of a whole mull, which is upon the best construction. ‘The four sails are fixed to an iron axis AA, by screwing them to an iron cro at one end of it. Two of these sails sre marked BB; upon the axis within the mill a cog wheel D is fixed, and this turns a wheel C, on the upper end of a vertical shaft, EE, extending from the top to the bottom of the mill, to turn the machinery: on the lower end of it is a large wheel F, which turns two pinions @ a, upon the spindles of the mill-stones 4 l; these are on the same construction as those described in our article FLour-MILL, to which we refer. AtGisa wheel upon the main axis, giving motion to a pinion on an horizontal’ shaft H, which has one or more wheels upon it, to receive an endle rope for turning the bolting and dre - ing machines; for a description of which see Bo.tTinG=M1ILL, We will now enter more fully into the me- chanism of the upper part of the mill, which is called its head or cap, marked TI, and con- tains the axis A A. ‘This is supported upon bearings, one near the sails and the other at its extreme end, as is Shewn in fig. 2, plate 176, which is an horizontal section of the head, shewing the circular kirb or wooden ring K, and the framing which is bolted upon it to support the axis. RRA The construction of the axis is shewn in figs. 3 and 4.of plate 176. It consists of an octagonal iron shaft with two cylindrical necks at c and d, where it rests upon its bearings, At the end it has a kind of box e, which has two mortices through it in perpendicular di- rections to receive the sails B B. ‘At the back of one of these mortices, and the front of the other, a projecting arm is left in the casting to receive screw bolts, which hold the sails fast in the mortices: the cog wheel is fitted on at D, its arms being bolted ‘against a flaunch, cast on the axis. The sails are braced by an irom stay f to each arm, proceeding from the end of a pole g, which is fixed at the end of the cast iron axis. The sails are formed of a sail cloth, spread upon a kind of lattice-work or framing, composed of rails morticed into the arms of the sails BB..The plane of these frames is inélined to the plane of the sails’ motion, at such an angle, that the wind blowing in the direction of the axis, acts upon them as inclined planes, and turns them about, with a power proportionate to the size of the sails and force of the wind. It is nece ary as the wind changes its direction to turn the sails about, that the axis may be always in the direction of the wind; this motion is eflected by turning the head of the mill round upen the walls or frame LL, composing the body of the mill. ~ At the top of this is a circular kirb, upon which a number of rollers are placed, and the kirb K of the cap lies upon these rollers, which are kept equidistant from each other by their centre pits being fitted into a circular hoop. By this means, though the head with the wheels and sails weigh many tons, they can be turned round to face the wind by a slight power; but in the best kind of windmill, such as is represented in our plate 175, the head is contrived to turn itself about whenever the wind changes. This is done by a small pair of sails M, fixed up in a frame projecting from -the back of the head; it has a wheel upon its axis turning another upon an inclined axis h, and this has a pinion turning a wheel é upon a vertical axis, at the lower end of which is a pinion working in a range of cogs, fixed round in the outside of the kirb. By this means, whenever the vane M is turned it moves the head of the mill slowly round; and with proportionate power. — Now if ever the wind varies in the least from the direction of the axis, it acts obliquely upon the’ vanes M, and turns them round, at the saine time setting the head ight again. But when the axis is right, the wind blows in the plane of the vanes, and has no effect upon them. The head of the mill is kept firmly in its place by rollers, figs. 5 and 6; the frames of these are bolted to the lower side of the framing of the head,’ and then the rollers apply to the inside of the kirb K: there are eight of these rollers, four of each kind. The pivot at the upper end of the vertical shaft E ts supported in a bearing bolted to a cro beam in the: framing of the head of the mill, and this is precisely in the centre of the head, that it may not vary as the head turns round. Many other. things are so evident in the drawings as to need ‘little explanation. Such are the walls N N, the different floors OO: at P P isa circular gallery all round the mill for the miller to go round, to take the cloth off the sails in high winds, or when the mill is to stop; this is done by untying the cloth at the extremity of the sails, and twisting it up like a rope, and tying the end of it again, in which state it presents no surface to the wind. At Q is a roller turn- ed round bya wheel'on the vertical shaft Bg 343 IMG:page343.webp:Plate (PDF page 343) 344 345 it is used to draw up the sacks ofcorn.from the bottom of the mill into the upper part, which is used as a storehouse. , For other particulars connected with wind- mills the reader may consult Smeaton’s Expe- rimental Enquiries, and Gregory's Mechanics. ~ WINDOW, an aperture or open place in the wall of a house to let in the light. (See - ARCHITECTURE.) The word is Welchi, uyné. dor, signifying the pa age for the wind. Win- dow is yet provincially denominated wind or in Lancashire; i. e. wind-door, or the pa age for air, as that for people was peculiarly called the door, Before the use of gla became general, which was not till towards the end of the twelfth century, the windows in Britain seem generally to have been composed of paper. Properly prepared with oil, this forms no con- _temptible defence against the intrusions of the weather, and makes no incompetent opening for the admi ion of the light. It is still used by our architects for the temporary windows of unfinished houses, and not unfrequently for the regular ones of our work-shops. But some of the principal buildings we may reasonably suppose to have been windowed in a superior manner. ‘They could, however, be furnished merely with lattices of wood or sheets of linen, as these two remained the only furniture of our cathedrals nearly to the eighth century; and the lattices continued in some of the meaner towns of Lancashire to the eighteenth; and in many districts of Wales, and many of the adjoining parts of England, are in use even to the present moment. These seem all to have been fixed in frames that were called caps amenta, and now therefore casements in Wales and Lancashire.