| Name and Model Number | Cameron’s rule |
| Country of Origin | UK |
| Date of Manufacture | ~ 1852 |
| Front Scales | Unknown |
| Back Scales | Normal 24” measuring rule |
| Scale Length | 11" |
| Type of Rule | Other |
| Construction | Boxwood & Brass |
| Area of Use | Other |
| Comment | 2-foot, 2-fold with calliper for unknown use.
Paul Cameron of 87 London Street, Glasgow was a mathematical instrument maker who took over from Robert Finlay and worked between 1851 and 1854. What this rule was for is unknown. The unusual calliper (the slide will only move in one direction) has not been seen elsewhere and the scales on the slide and those on the stock which are labelled Tan and Sine do not appear to relate to anything else. There are also a plain scale and two other scales of unknown function on the second arm. The reverse of the rule is calibrated in various fractions of an inch for the 24” length of the two arms. |
| Rarity | RRR |
| Donor | Collection of an English gentleman |
| Match Number | 90 |
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| RR | = Rare -- 1 of 25 collectors has one; it may take a year to find an example in the marketplace. |
| RRR | = Very rare -- only very few known to collectors; may take several years before one comes up for sale. |
| RRRR | = Extremely rare -- a museum piece; unlikely that an example will ever come up for sale. |