Set of mathematical drawing instruments by G.Adams, in Sheraton case, oak and mahogany, mid 18th century. The case contains a sector, parallel ruler, pair of callipers, rectangular protractor, curve drawing instrument and compasses and dividers.
Playskool wooden toy, a wooden framework with rotating blocks bearing numbers and symbols to do arithmetic. 1960-1980. Toys to help with arithmetic were introduced from the start of the 20th century.
A. Sonnenschein's improved Arithmometer' made by George Philip and Son of London and Liverpool, late 19th century. This device, which showed units, rods of 10s, and squares of 100s, anticipated many 20th century arithmetical teaching aids. Sonnensche
Exactus stylus-operated adding and subtracting device, with swivelling half plate for add and subtract options, marked "Mini-Add Made in England", c. 1950. The Exactus is one of several simple stylus-operated calculators to have been popular in the
A single surface model made by Alan Bennett in Bedford, 1995. It consists of a Klein bottle cut to form one four-twist band. A Klein bottle is a surface which has no edges, no outside or inside and cannot be properly constructed in three dimensions.