| Name and Model Number | Hawthorn’s rule |
| Country of Origin | UK |
| Date of Manufacture | c1832 |
| Front Scales | Routledge variant |
| Back Scales | Routledge variant |
| Scale Length | 11” |
| Type of Rule | Other |
| Construction | Boxwood & German silver |
| Area of Use | Other |
| Comment | A 2-foot, 2-fold rule used for steam engine design.
Hawthorn’s rule appears to be especially attractive as a presentation rule as many are seen with an engraved name somewhere on it. This particular fully bound example by J. Tree (1850 – 1895) is extremely attractive with its German Silver furniture and outside binding on the usual boxwood finish. Two very different instruction booklets are known to have been published, the first in 1832. |
| Rarity | RRR |
| Donor | Collection of an English gentleman |
| Match Number | 56 |
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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. |