Six inch silver sector signed "Ramsden, London" with attached set square, late 18th century. Sectors were used from the end of the 16th century until the mid 19th century for calculations involving proportion. They were ingraved with logarithmic and
Six inch Brass sector 1720-1753 signed T Heath Fecit, decorated on hinge and legs with floral patterns. Sectors were used from the end of the 16th century until the mid 19th century to perform calculations involving proportion. They were inscribed w
Wine diagonal, a type of gauging rod, by J.Stutchbury, 1797-1826. These were used by Excise Officers together with slide rules to calculate the volume of wine in wine casks, and thence the duty payable. Until 1826 the volume of a wine gallon was diff
A single surface glass vessel made by Alan Bennett in Bedford, 1995. It consists of three Klein bottles arranged in a column which when cut form a pair of five-twist Mobius strips. A Klein bottle is a surface which has no edges, no outside or inside
Ready reckoner giving the value of discounts of 10%, 15% and 20% on quantities between 15 and 36. This was probably a one-off instrument for use in a particular shop or workshop.