| Name and Model Number | Mast maker’s rule |
| Country of Origin | UK |
| Date of Manufacture | c1790 - 1870 |
| Front Scales | Coggeshall variant plus tables |
| Back Scales | Tables of ratios of masts, spars and hull dimensions |
| Scale Length | 11” |
| Type of Rule | Other |
| Construction | Boxwood & brass |
| Area of Use | Other |
| Comment | A 2-foot, 2-fold rule used for Shipbuilding calculations.
Mast maker’s or Ship’s Carpenter’s slide rules are perhaps surprisingly more common than might be anticipated; however no two examples by a number of makers are exactly the same. Examples with dimensions other than 2-foot, 2-fold are also known and this is a splendid example by an un-named maker. Other examples are known from well known makers such as Lorkin, Heather and Sampson Aston. These are an example of a slide rule for a very specialist trade, how much such a rule would have actually been used in the design and building of a square–rigged ship is not known. |
| Rarity | RR |
| Donor | Collection of an English gentleman |
| Match Number | 59 |
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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. |