WIND-MILL. 



made into a rack, working in a wheel upon which a weight 

 was hung. By this means, when the wind blows too hard, 

 the blinds turn upon their pivots, and by the racks draw out 

 the rod which partes through the axis, and raife the weight ; 

 but as foon as the wind abates, the weight brings the bhnds 

 to their former pofition. 



A patent was granted in 1804 to Mr. John Bywater of 

 Nottingham, for a method of clothing and unclothing the 

 fails of wind-mills while in motion. The invention confifts 

 in a manner of rolling or folding up, and unfolding again, 

 the cloths of common wind-mill fails while in motion. It 

 is effected by placing a long roller in the direiSion of the 

 length of the whip round which the cloth is rolled ; the 

 inner end of the roller is furniflied with a pinion, which 

 engages in the teeth of a circular ring of cogs fixed to the 

 rtiaft-head, clofe behind the back-ftocks, with the hberty of 

 turning round independent of the (haft. Another roller is 

 placed at the back-fide of the fail, round which feveral 

 cords pafs, and are conveyed over pulleys at the edge of 

 the fail, and then made faft to the cloth at different diilances 

 along its length. The objeft of this fecond roller is to 

 clothe the fail, in the fame manner as the firll-mentioned roller 

 unclothed it. The inner end of the back roller is furnifhed 

 with a bevelled pinion, which afts in the teeth of a ring of 

 cogs placed concentric with the one before defcribed, which 

 has alfo the liberty of turning round independent of the 

 fhaft. Suppofe the fails to be completely clothed, and 

 turning round by the wind, the two rings of cogs revolve 

 with the axis, and therefore produce no effedt on the 

 pinions ; but if the wind blows too violent, and it becomes 

 neceffary to partly unclothe the fails, the miller pulls a cord 

 which is connefted with a lever in the head of the mill. 

 This lever comes in contaft with a projeAion on the ring 

 of cogs belonging to the rollers, upon which the cloth winds. 

 Now it is evident, that if the ring of cogs is held faft, and 

 the fails continue to revolve, it will caufe the pinions to 

 turn round and roll up the cloth upon the rollers ; on the 

 contrary, if the wind falls, the fails will require to be more 

 clothed, which is effected by the fame lever being moved 

 farther, fo as to quit the ring of cogs it held before, and 

 hold the other fail, which will put the rollers at the back of 

 the fails in motion, and by winding the cords upon them, 

 draw the cloth off the fail-roller, which increafes the fiirface 

 for the wind to aft upon. We have not entered into the 

 minute details of this invention, as given in the patent, for 

 it would have exceeded our limits, but only given a fufR- 

 cient defcription to enable a perfon to underftand the means 

 of effefting the regulation. 



Horizontal Wind-Mills. — Thefe are of various kinds ; 

 but only one kind that we know of has been put to any 

 valuable ufe. 



Horizontal wind-mills were a favourite fpeculation a cen- 

 tury ago ; and the Theatruni of the celebrated Leopold con- 

 tain a great variety, but they are all upon one or other of 

 two principles. In one of thefe, a very large wheel, like a 

 water-wheel, is mounted witli its axis in a perpendicular 

 direftion. It confifts of feveral circular wheels fixed upon 

 the axis ; and it has large boards or vanes fixed parallel 

 to its axis, and arranged at equal diftances round the cir- 

 cular wheels. Upon thefe vanes the wind can act to blow 

 the wheel round ; but if the wind were to aft upon the 

 vanes at both fides of the wheel at once, it would have no 

 tendency to turn the wheel round ; hence one ilde of the 

 wheel muft be ftieltered from the wind, whilft the other is 

 fubmitted to its full aftion. For this purpofe, the whole 

 wheel is inclofed within a large cyhndrical framing of wood, 



which is furnifhed with doors or (butters on all fides to open 

 at pleafure, and admit the wind, or to (hut and ftop it. If 

 all the (butters on one fide are open, whilft all thofe on the 

 oppofite fide are (hut, the wind, afting with undiminifhed 

 force on the vanes at one fide, whilft the oppofite vanes are 

 under fhelter, turns the mill round ; but whenever the wind 

 changes, the difpofition of the open vanes muft be altered, 

 to admit the wind to ftrike upon the vanes of the wheel in 

 the direftion of a tangent to the circle in which the vanes 

 move. A horizontal wind-mill is thus defcribed in Leopold's 

 Theatruni Machinarum for grinding corn with one pair of 

 ftones. A ftrong upright axis is fo poifed on a pivot at 

 the lower ends, and fuftained in a collar or bearing, as to 

 turn round. Into this feveral long arms are fixed, in the 

 manner of radii, and at the extreme ends of each arm a 

 vane is fixed, to receive the aftion of the wind. Thefe 

 vanes are made of two or more moveable leaves, which 

 clofe up flat like a book, when they are ?t that fide of the 

 circle which moves in a direftion to advance towards the 

 wind ; fo that only the edges of the boards are oppofed to 

 the wind ; but when thefe vanes arrive at the oppofite fide 

 of the wheel, fo that the wind blows upon them, the leaves 

 fly open, and expofe their full furfaces to the wind, and 

 receive the impulfe thereof. 



A horizontal wind-mill is defcribed by Dr. Hooke in the 

 Philofophical CoUeftions for 1681. It confifted of four 

 vanes mounted upon vertical axes, and arranged round in a 

 circle by the upper and lower pivots of the vanes being 

 received into holes in the rims of two horizontal wheels 

 fixed upon the fame vertical fhaft. The vanes were dif- 

 pofed in fuch a manner, that on one fide of the wheel each 

 vane prefented its furface to the wind, whilft the one on the 

 oppofite ttood edgeways, fo as to move through the air 

 without much refiftancc. This was effcfted by cog-wheels 

 placed on the lower pivots of the vanes, and fo arranged, 

 that as one vane turned round upon its pivots, the whole 

 number moved together, and the motion was given to them 

 by a cog-wheel fixed faft to the framing over the wheel, 

 but concentric with it. This wheel communicated, by 

 means of an intermediate wheel, with the wheels on the 

 axes of the vanes. 



The aftion of this machine is as follows: — Suppofe 

 the wind blowing at the wheel ; it afts againft that vane 

 which is at right angles to its motion, to turn the wheel 

 round upon its axis. The oppofite vane prefenting its edge 

 to the wind oppofes very little refiftance. The motion of 

 the wheel upon its axis turns the vanes round upon their 

 pivots, by means of the fixed cog-wheel before defcribed ; 

 fo that by the time that one has paffed out of the di- 

 reftion of the wind, another arrives in the fame perpen- 

 dicular pofition ; and when the wheel has made half a 

 revolution, the vane which ftood edgeways will be perpen- 

 dicular to the vvind, and the one which before ftood per- 

 pendicular will be edgeways ; thus a continued motion is 

 produced without the wheel being cafed up. 



Horizontal wind-mills, which are inclofed in a houfe with 

 blinds on all fides, are very fully defcribed in Jacob Leo- 

 pold's Theatrum Machinarum, 1724; but we believe they 

 were firft praftifed in this country by captain Hooper, 

 who erefted one at Margate, and another at Batterfea. 

 The latter is upon a very large fcale, and is ufed for 

 grinding corn ; but at prefent it does not work with much 

 advantage, as the repairs are more confiderable in propor- 

 tion to the power it exerts, than in the mills with fails con- 

 ftrufted in the common manner. 



In Plate JVind-Mill,Jig. I, is an upright feftion, and^f^. 2. 

 10 a plan 



