6075 x 4050 px | 51,4 x 34,3 cm | 20,3 x 13,5 inches | 300dpi
Date de la prise de vue:
23 septembre 2009
Lieu:
Royal Greenwich Observatory, London, England, UK
Informations supplémentaires:
In 1849, Charles Shepherd, of 53 Leadenhall Street, London, had patented a system for controlling a network of master and slave clocks using electricity (or galvanism, as it was called). This is one of the earliest electrically driven public clocks and was installed here in 1852. The dial always shows Greenwich Mean Time (GMT) or Universal Time (UT). In summer Britain converts to British Summer Time (BST), which is an hour ahead of GMT, and the clock then appears one house 'slow.' Being a 24-hour clock, the hour hand marks noon (XII) at the bottom of the dial and midnight (O) at the top. The time is accurate to 0.5 of a second. The clock, was a slave mechanism controlled by electric (galvanic) pulses transmitted by a master clock inside the main building. The 'network' of master and slave clocks at the Royal Observatory was constructed and installed by Charles Shepherd in 1852.
