. Machinery for metalliferous mines : a practical treatise for mining engineers, metallurgists and managers of mines. l directingwheel in the rear, which drives asmall worm-wheel gearing into fixedteeth on the top of the main sail is composed of a numberof separate boards which can be fullyopened when it is required to stop themill, or partially closed, according tothe force of the wind, by means ofthe chains hanging in the rear, whichare connected with the sails througha system of levers worked by a rodpassing through the centre of themain shaft. An automatic governingarrangemen
. Machinery for metalliferous mines : a practical treatise for mining engineers, metallurgists and managers of mines. l directingwheel in the rear, which drives asmall worm-wheel gearing into fixedteeth on the top of the main sail is composed of a numberof separate boards which can be fullyopened when it is required to stop themill, or partially closed, according tothe force of the wind, by means ofthe chains hanging in the rear, whichare connected with the sails througha system of levers worked by a rodpassing through the centre of themain shaft. An automatic governingarrangement can be supplied if re-quired, so that the sails will adjustthemselves to the variations in the force of the wind, and so maintainan approximately even rate of speed. The pressure of the wind persquare foot is a quantity ever varying according to the speed at whichthe wind is travelling, and this may be ascertained from the table givenabove. The horse-power of a windmill may be obtained from thefollowing formula (Molesworth):— HP = Horse-power. V = Velocity of wind in feet per second. A = Total area of Fig. 21.—Wind Engine. HP = AV^1,080,000 A = HPi,080,000 THE VENTILATION OF MINES. 33 The following particulars will show the approximate horse-power,size, and cost of wind engines such as that shown in the illustration : Approximate Horse-power, Breeze 14 miles per Hour (Pleasant Breeze). Diameter of WindEngine. Price of Wind Engine,without Supports. Price of Iron andSteel Tower. J horse-power. 13 ft- ;^4S £2s a 4 I , 14 „16 „ 5060 2730 2 , 20 ,, 90 40 3 4 24 „28 „ no180 45 50 4i6 30 .. 35 » 200 250 5560 The Ventilation of Mines.—The ventilation of metalliferous minesis not surrounded with the same difficulties and dangers as is that ofcollieries, where, owing to the large quantities of gas given off by the coal,most careful attention has to be paid to the question. As regards metalliferous mines, especially when they are once openedup, the natural ventil
Size: 1048px × 2384px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1902
