Surveying Instrument Collection
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Maker |
Wallace & Tiernan Product Inc. |
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Model |
FA112 |
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Serial Number |
WP55421 |
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Dimensions |
Length 160mm, Width 160mm, Height 130mm |
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Image |
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Description |
This instrument is used for measuring the altitude of terrain with hundred feet graduations. It provides a rapid means of heighting, where errors of the order of 3-15 feet are acceptable. The application of this instrument is restricted to providing ground control for small and medium-scale photogrammetric mapping, and to reconnaissance surveys. The instrument is fitted in a fine wooden box. The instrument responds to changes in atmospheric pressure by expansion or contraction, and this movement is transferred via cogwheel and lever transmission onto a index such that the elevation can be directly read on a circular scale. Readings up to 75'000 feet (22'860 m ?) altitude can be taken, and the graduations are located on two separate scales, where the inner scale consists of graduations from 500-3900 (152-1189 m ?) and the exterior scale from 3900-7500 (1189-2286 m ?).
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History & comments |
The Wallace & Tiernan range of altimeters and aneroid barometers operate on the same general principle as other altimeters and aneroid barometers, but incorporate such refinements as shock-resistant jewelled bearings, a specially designed device to eliminate backlash between the pointer and the mechanism, and the individual graduation of the scale for each instrument. |
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Conservation |
Wooden box |
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Condition |
Good |
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Remarks |
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Dates |
Manufactured in 1950 (approx). Catalogued in 1997 & 2005 |
