- Museum number
When closed this brass instrument resembles a large pair of compasses, with flat limbs inscribed on all sides and a highly decorated hollowed joint. One limb has foldable sights on the outside edge, one of which is missing.
When fully opened to 90°, further plates, two skeletonized folding geometrical squares and a third arm with a fiducial edge and a folding sight with a spike can be folded out from inside the hollow limbs. Even in the upright position, this sight slides into a slot in the upper side of one limb. A second sight arranged in the same way is broken off.
A movable ring around the joint with a small hole suggests that a plumb bob was fitted to the instrument.
The scales found here are inaccurately engraved and laid out:
1) On one limb a 9 3/4 inch scale, numbered by 1. Each section is divided to 32 parts and consecutively numbered by 4 up to 312.
2) On the edge of this limb and on the face and edge of the other limb are the scales usually found on folding rules for calculating areas and volumes.
3) A scale for board measure, marked 'Borde measure', and a scale for timber measure, marked 'Tim measure'. The board scale runs from 13 to 36, the timber scale from 13 to 36. Both scales are supplemented by scales providing the board and timber measures from 1 to 11 inches, but in this case only represented by plain boxes.
1) Over both legs a list of cannons: 'The Names of Ordenan'; the weight of every cannon: 'H Much euery pece wayeth'; the diameter of the barrel: 'H Hie die piece is in the mouthe'; the diameter of each cannonball in inches: 'H Many Inches hie the bullett is'; the amount of powder needed for each cannonball or shot in pounds: 'H many lb of powder euery pece shot'; and how many pounds each ball weighs: 'H Many poude euery shote wayeth'. (The 'Basilisco', normally to be found in this maker's list, is not named, although there is space for more entries in the list.)
2) Below this list on the left limb on its face and edge is 'The table of timber measure' in feet, inches and fractions of inches.
3) Inscribed on the left-hand column beneath the figures is the inscription 'SQVARE YNCHES OF THE TYMBRE'.
The signature of the maker is below this list close to the pointed ends of the limb.
4) On the face of the other limb are scales for the conversion of measures in Latin, titled 'DE PARTUBVS MENSVRAE SEV SPECIEBVS GEOMETRIAE PRACTICAE', as follows: 'Granu igitur hordei, est minima mesura', 'Digitus habet 4 grana per latera contigue disposita', 'Vncia habet 3 digitos', 'Palmus habet 4 digitos', 'Dichas habet 2 palmos', 'Spithama habet 3 palmos', 'Pes habet 4 palmos', 'Sequipes habet 6 palmos', 'Gradus habet 2 pedes', 'Passus simplex 2 pedes cum dimidio', 'Passus Geometricus quo Vtitur', 'Cosmometra habet 5 pedes', 'Pertica habet 10 pedes', 'Cubitus habet 6 palmos', 'Stadium habet 125 passus', 'Leuca habet 1500 passus', 'Miliare Italicum habet 1000 passus', 'Miliare Italicum habet 8 stadia', 'Miliare Germ cont 4000 passus', 'Miliare Ger magnum 5000 passus', 'Miliare Germ comune 32 stadia'.
When the limbs are completely opened, two folding squares are fully spread.
The larger one is marked with a shadow scale inscribed 'Latus Vmbrae Rectae' and 'Latus Vmbrae Versae' with two different scales: one 0 to 60 to 0, the other 0 to 45 to 0. The same scales are inscribed on the other side, but not labelled.
The smaller square has a scale 0 to 90 and 0 to 45 on one side and a scale 0 to 90 on the other side.
- Production date
- 1575-1585 (ca. 1580)
Height: 7 millimetres
Length: 320 millimetres
Width: 31 millimetres
- Curator's comments
This is one of three surviving gunner's rules by Humfrey Cole, two of which are in the British Museum (see also Epact 47296 [BM reg. no. 1912,1101.1]). They offer a wide range of applications beyond those of an ordinary folding rule which makes them a valuable instrument in surveying, gunnery and trade.
The instrument is undated, but comparison with other instruments by the same maker allows it to be dated to circa 1580.
In contrast to the scales found on other Humfrey Cole instruments, those found here are inaccurately engraved and laid out.
[S. Ackermann, EPACT 1998, http://www.mhs.ox.ac.uk/epact/catalogue.php?ENumber=21385]
According to Turner, this complicated instrument is used either closed, to read the tables that cover both arms, or opened out completely to form a geometrical quadrant. The joint has a relatively large central hole (diameter 15) probably to hold a magnetic compass. He considers this instrument to be an early work by Humfrey Cole, perhaps of ca. 1570, primarily because his name is given here as 'Humfray Coolle'; see Turner 2000, pp.121, 124.
- Not on display
Latest: 2 (Mar 2017)
5 (Feb 1996) Verdigris.
- Acquisition date
- Britain, Europe and Prehistory
- Registration number