Spirograph a hypocycloid. Spirograph Spirograph is a geometric drawing toy that produces mathematical roulette curves of the variety technically known as hypotrochoids and epitrochoids. It was developed by British engineer Denys Fisher and first sold in 1965. The name has been a registered trademark of Hasbro Inc. since 1998 following purchase of the company that had acquired the Denys Fisher company. The Spirograph brand was relaunched worldwide with original product configurations in 2013 by Kahootz Toys. In 1827 English architect and engineer Peter Hubert Desvignes developed his "Speiragraph", a machine to create elaborate spiral drawings, intended to prevent bank note forgeries.
Denys Ovenden the Collins Guide to Freshwater Life a small share in the Collins Fungi Guide. Denys was commissioned by the Open University to prepare a poster accompanying David Attenborough's BBC series Life in Cold Blood. After a period of 15 years’ work, Galápagos, a Guide to the Animals and Plants. This finally went to print after the addition of illustrations two other recently discovered rodents and the elusive pink iguana. Denys Ovenden Denys Ovenden was born on April 1, 1922. His preoccupation with drawing began very early, since there are drawings on the fly-leaves of books from that period. His natural