| 1. | Recently dendrochronology had been employed to date the timber pit props.
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| 2. | Steel supports began to replace the traditional timber pit props.
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| 3. | She was carrying a cargo of magnesite and pit props.
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| 4. | Gin Pit had a sawmill and supplied pit props to neighbouring collieries.
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| 5. | He purchased half a dozen landed estates in Saxony to supply timber for pit props.
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| 6. | The thinnings were graded and the straighter poles used as pit props in the coal industry.
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| 7. | The use of wooden pit props to support the roof was an innovation first introduced about 1800.
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| 8. | The pit props and steel bands are not for show, but to hold up the mine roof.
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| 9. | The south-east corner of the keep was undermined and the pit props soaked in pigs fat.
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| 10. | Between 1930 and 1935 Peter Parsons from Long Island was contracted to produce pit props for the overseas market.
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