March 2014
Page 32

Thomas Hogben’s Perpetual Calendar

Research into a rare brass perpetual calendar attributed to Thomas Hogben (1702–1774), a surveyor and dialmaker from Kent. The instrument comprises three concentric disks engraved with dates, months, and astronomical signs, and features windows showing day length and sunrise/sunset times. Its construction around 1752 coincided with Britain's adopting the Gregorian calendar.
Dialling Tools, Historical Dials, How Sundials Work

Nigel Rainton