WIND-MILL. 



hawk, called alfo by fome thejlannel, but more ufually the 

 keftrel, and known among authors by the names of the lin- 

 nunculus and cenchris. 



WiSD-InJIruments, in Mufu, are inftruments played by 

 wind, chiefly by the breath ; in contradiilindlion to ftringed- 

 inftrunients, and inftruments of the pulfative kind. 



The wind-inftruments known to the ancients were, the 

 tibia, fjlula, or fyringa of Pan, confifting of feven reeds, 

 joined fidewife ; alfo, organs, tubit, cornua, and the itiuus. 

 Thofe of the modems are, the JIule, bagpipe, hautboy, trum- 

 pet, &c. See lNSTRUi\fENT, and Music. 



VJiSTt-Mill, in Mechanics, a machine which is put in 

 motion by the force of the wind. Wind-mills are in gene- 

 ral applied to the purpofe of grinding corn, but are occa- 

 fionally ufed to give motion to machines for raifing water, 

 fawing-mills, or for other piirpofes. We lliall in this article 

 confider the wind-mill as a firft mover, or primum mobile, 

 which may be applied to many purpofes. 



The invention of wind-mills is not of very remote date. 

 According to fome authors they were firft ufed in France 

 in the fixth century ; while others maintain that they were 

 brought to Europe in the time of the crufades, and that they 

 had long been employed in the Eaft, where the fcarcity of 

 water precluded the application of that powerful agent to 

 machinery. 



The wind-mill, though a common machine, has fome 

 things in it more ingenious than is ufually imagined. 

 Add, that it is commonly allowed to have a degree of per- 

 fedion, which few of the popular engines have attained to, 

 and which the makers are but httle aware of : though the 

 aid of mathematics has furnilhed ample matter for its im- 

 provement. 



The vertical wind-mill, which is the kind in moft common 

 ufe, confifts of an axis or (haft A B, [Jig. i . Plate II. IVind- 

 MiU,) placed in the direAion of the wind, and ufually in- 

 clining a little upwards from the horizontal line. At one 

 end of this, four long arms or yards, S, T, V, W, are fixed 

 perpendicular to the axis, and crofs each other at right 

 angles ; into thefe arms fmall crofs-bars are mortifed at right 

 angles ; and other long bars are joined to them, which are 

 parallel to the length of the arms ; fo that the bars rnterfeft 

 each other in the manner of lattice-work, and form a furface, 

 on which a cloth can be fpread to receive the aftion of the 

 wind. Thefe are called the fails ; they are in form of a tra- 

 pezium, and are ufually nine yards long an<l two wide. 



The circular motion is produced by the obliquity of the 

 planes of thefe furfaces, from the plane in which all the four 

 arms are fituated ; by thefe means, when the wind blows in 

 the direftion of the axis, it does not impinge upon the fails 

 at right angles to their furfaces, but ftrikes obliquely ; hence 

 the effort of the fail to recede from the wind, caufes it 

 to turn round with the common axis, and the four fails are 

 all made obhque in the fame direftion, fo as to unite their 

 efforts for the common objeft. 



That the wind may aft with the greateft efficiency upon 

 the fails, the wind-lhaft muft have the fame direftion as the 

 wind. But as this direftion is perpetually changing, fome 

 apparatus is neceffary for bringing the wind-(haft and fails 

 into their proper pofition : this is done by turning the axis 

 and fails round in an horizontal direftion. There are two 

 methods of effefting this. In the old mills, like^^. i , the whole 

 of the mill or building which contains tce machinery is fuftained 

 upon a vertical poft, firmly fixed as a ftand or foot, upon which 

 the whole machine can be turned by a lever, to prefent the 

 fails to any quarter of the horizon from whence the wind 

 blows ; and hence thefe are called poft wind-miUs, and are 

 neceffarily made of wood. The other kind,/^. 2, is called a 



fmock-mill, in which only the dome-cap or head, which 

 contains the axis of the fails, and covers the great cog- 

 wheel, turns round horizontally ; the other parts of the 

 machinery being contained in a fixed building, which rifes 

 up in form of a conical tower of mafonry, and is furmounted 

 by this moveable cap or dome, which is fupported on rollers, 

 fo as to turn round eafily. 



As both the common methods of adjufting the wind-lhaft 

 require human affiftance, it would be very defirable that 

 the fame effeft ftiould be produced folely by the aftion of 

 the wind. This may be done by fixing a large wooden vane 

 or weathercock at the extremity of a long horizontal arm, 

 which lies in the fame vertical plane with the wind-ftiaft. 



By thefe means, when the furface of the vane and its dif- 

 tance from the centre of motion are fufficiently great, a very 

 gentle breeze will exert a fufficient force upon the vane to 

 turn the machinery, and will always bring the fails and 

 wind-fliaft to their proper pofition. This weathercock, it 

 is evident, may be applied either to machines which have a 

 moveable roof, or to thofe which revolve upon a vertical 

 arbor. This method is praftifed in fmall machines ; but a 

 vane of fufficient power to turn a large mill about would 

 be unwieldy. A much better method is therefore praftifed 

 in the beft mills, as we (hall foon defcribe. 



In a. pqfi-mi!l the building muft neceffarily be of fmall fize, 

 and it can only contain one pair of mill-ftones. For this pur- 

 pofe, a large cog-wheel is fixed upon the main-fhaft or axis 

 of the fails ; the cogs are placed in the face or flat furface of 

 the wheel, and aft upon the teeth of a pinion, which is fixed 

 upon the vertical axis or fpindle of the mill-ftones. The 

 mill-houfe is of a rcftangular figure, but narrow in the 

 direftion which is prefented to the wind: it is two ftories 

 high, the main-fhaft and mill-ftones being in the upper 

 chamber, whilft the lower is only ufed to contain facks of 

 flour, and alfo to receive the poft on which the mill turns 

 round horizontally to face the wind. This poft is a very 

 ftrong tree, and is held perpendicularly by fixing it upon 

 the middle of long timbers, which form a large crofs on the 

 ground, and are the bafement of the whole mill. The poft 

 is fixed perpendicularly by means of feveral oblique braces, 

 extending from the ground-crofs to the middle part of the 

 poft ; but ten or twelve feet of the upper end of the poft 

 muft be round, and clear from the obftruftion of the braces. 

 This part of the poft rifes up through the middle of the lower 

 chamber, in the floor of which a circular collar is formed, 

 to furround the lower part of the poft exaftly. At the upper 

 end of the poft is a pivot or gudgeon, which enters into a 

 focket fixed in the middle of the upper floor, and to one of 

 the ftrongeft crofs-beams, becaufe this beanimuft fuftain the 

 whole weight of the mill. In this manner, the whole mill 

 can turn about upon the vertical poft, but remains always in 

 equihbrio. To make it firm, and prevent it from turning 

 about at every moment, a ftrong framing is united by joints 

 to the back part of the mill-houfe, and defcends in a Hoping 

 direftion till it touches the ground : this is fumifhed with 

 fteps, fo that it ferves as a broad ladder to afcend to the 

 mill ; but another ufe is to fteady the mill, becaufe the end 

 of this frame, which is very heavy, refts on the ground, and 

 (hort pofts are fixed in a circle round the mill at regular 

 intervals, to which the end of the ladder is faftened with 

 cords. In order to turn the mill about, a rope is faftened 

 to the end of the (loping ladder, and is carried up to the top 

 of the mill in an inchned direftion. By means of a ftrong 

 lever, or a tackle of pulleys, this rope can be (hortened, fo as 

 to hft up the ladder clear of the ground ; and then, by pu(h- 

 ing it like a long lever, the whole mill is turned round. To 

 obtain more force, a fmall capftan is often provided to draw 



a rope 



