Surveying Instrument Collection
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Maker |
E. R. Watts & Son Ltd., London, England |
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Model |
N/A |
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Serial Number |
18340 |
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Dimensions |
Telescope length 290mm, Height 150mm |
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Image |
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Description |
This tilting level by E. R. Watts & Son Ltd. is a three footscrew "reversible" level typically designed for high quality levelling. It features a reversible tubular level, which allows the divergence between the line of collimation and the bubble tube axis at two staff readings (180º apart) to be automatically eliminated by taking the mean of the two readings. The bubble tube has two reflecting prisms in opposite positions at each end. The telescope is supported at its centre by a pivot and may be tilted (up and down) by turning the "tilting screw" which is located on the stage component of the level between the telescope and the base. This tilting screw enables the telescope to be precisely levelled before each staff reading, without altering the height of the telescope. The screw carries a graduated drum working against an index. The objective end of the telescope features a sliding cover which is used to protect the aperture lens when the instrument is not being used. |
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History & comments |
The bubble of the level tube defines a horizontal plane, and, when the instrument is in adjustment, the line of sight which passes through the centre of the cross hairs and the optical centre of the telescope is parallel to this plane. |
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Conservation |
In a wooden box |
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Condition |
Good |
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Remarks |
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Dates |
Manufactured in 1938 (approx). Catalogued in 1997. |
