| 41. | It appears on the U . S . Geological Survey Map.
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| 42. | The 1665 Down Survey map depicts it as " Burrin ".
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| 43. | The 1665 Down Survey map depicts it as " Derrycashan ".
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| 44. | It also sells CD-ROMs with the base Geological Survey maps for home use.
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| 45. | The 1809 Ordnance Survey map shows the canal very clearly.
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| 46. | The resulting radiological survey map is then used by excavators.
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| 47. | Land survey maps drawn in the 1890s show four schools.
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| 48. | It was marked on the 1838 Ordnance Survey map.
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| 49. | He also produced Ordnance Survey maps prior to 1805.
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| 50. | Some archaeological sites are marked on Ordnance Survey maps.
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