| Name and Model Number | Routledge’s rule |
| Country of Origin | UK |
| Date of Manufacture | c1860 |
| Front Scales | Routledge engineering (Soho) scales: D = 1 - 10 |
| Back Scales | Gauge points, conversion factors, circles, and pumping engine constants |
| Scale Length | 6″ |
| Type of Rule | Other |
| Construction | Ivory & German silver |
| Area of Use | Other |
| Comment | A 2-foot, 4-fold rule used for Engineering.
This beautiful version of Joshua Routledge’s slide rule is in the more unusual 2-foot, 4-fold format, and in ivory with German Silver furniture, not the most practical of combinations, but extremely attractive. This one is not in the pink of condition, but is still a joy for any collector. It was made by Buck & Hickman of Whitechapel Road, London; (c1820 – present day). The 6″ slide rule is perfectly usable and this model includes a quite usable protractor which is accurate to 5º. Two-foot, 4-fold rules are very attractive, whether in ivory and electrum or even in boxwoods and brass. Note that an equivalent ivory rule is about 30% heavier than its boxwood equivalent. |
| Rarity | RR |
| Donor | Collection of Peter Hopp |
| Match Number | 68 |
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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. |