Surveying Instrument Collection
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Maker |
Precision Instruments Co., Sydney |
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Model |
N/A |
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Serial Number |
N/A |
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Dimensions |
Length 35mm, Width 35mm, Height 25mm |
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Image |
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Description |
This instrument is also referred to as a 'prism square' and it consists of a prism of glass protected by a square metal shield. It is a small pocket instrument, slightly larger than a wrist watch and is typically used for setting out a line at right angles (90º) to another. It is considered to be an easier and quicker solution than the use of a theodolite, notably when taking approximate offsets from a chain line. See also item 0181 in this collection. |
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History & comments |
The optical square uses the 'laws of reflection of light' as it's basic principle. The instrument was invented in 1740 by a London mechanic by the name of Adams (1720-1773). |
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Conservation |
In a case |
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Condition |
Good |
| Remarks |
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Dates |
Manufactured in 1930 (approx). Catalogued in 1997 |
