| 21. | Sails made of reeds spun around a vertical shaft.
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| 22. | But there are about 27 visible vertical shafts or air vents inclusive of branch gallery.
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| 23. | The mine is developed mainly through two vertical shafts up to 22nd level at present.
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| 24. | Work began in February 1825, by sinking a diameter vertical shaft on the Rotherhithe bank.
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| 25. | A raise is often a 6 12 foot square vertical shaft divided into two sections.
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| 26. | The steering column was inclined backwards unlike the vertical shaft on many of its contemporaries.
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| 27. | Steel plates are used primarily on horizontal shafts, but are used on vertical shafts occasionally.
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| 28. | Vertical shafts were sunk to reach the deeper seams.
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| 29. | The excavated material is usually transported by means of leather bags up the vertical shafts.
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| 30. | Power was transmitted by a main vertical shaft with bevel gears to the horizontal shafts.
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