| Name and Model Number | Coggeshall-Dialling rule |
| Country of Origin | UK |
| Date of Manufacture | c1750? |
| Front Scales | Timber Calculating scales – note Girt Line |
| Back Scales | Scamozzi sector lines |
| Scale Length | 11” |
| Type of Rule | Other |
| Construction | Boxwood and Brass |
| Area of Use | Other |
| Comment | a 2-foot, 2-fold rule.
Not sure of its area of use: perhaps this might be more architectural? The unusual mixture of scales on the two sides of this early 2-foot, 2-fold slide rule by an unknown maker are difficult to rationalise! The front appears to have the standard suite of Coggeshall Timber and calculating scales aimed at calculating the volume of usable timber in a standing tree, while the unusual sector scales on the back with unknown gauge points may have something to do with calculating roof trusses – but that is something I would not set in stone! Part of the delight of these 2-2 slide rules is the unusual combinations one finds, a Dialling and Routledge is also known, speculating what it was used for or by whom, is interesting! |
| Rarity | RRRR |
| Donor | Collection of an English gentleman |
| Match Number | 67 |
| Thumbnail |  |
| 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. |