See also:

• Reference: Time: Alternative Systems  (5)

• Abbey Clock Clinic - Mark Headrick's Horology Page - Traditional horology website with information and mantainance tips. Technical descriptions and troubleshooting of escapements. Grandfather clocks, wall clocks, and watches.
• Allan Variance -- Overview by David W. Allan - Core algorithm of international time scale has multiple metrology applications, from atomic clock frequency characterization to definition of the meter. Equation, explanation and publications.
• Antique Horology - The Horological Foundation's directory of web sites for watches, clocks, instruments and barometers.
• Clocks and Time - Horological index for organizations, clock and watch museums, related software, mailing lists and links. Maintained by Gordon T. Uber.
• Cumbria Clock Company - Company specialized in all aspects of work connected with church clocks, public clocks, and tower clocks which includes the full historical restoration of antique clock movements.
• David Knight - Watchmaker from UK - Articles and pictures of the first two watches made by David Knight. Rich artistic pictures.
• Daylight Saving Time - History of daylight saving time and how we use it to save energy.
• Functionning of a Simple Mechanical Watch - Explanation of the roles of components of a wristwatch.
• The Horology Source - Gateway to all aspects of clocks, watches, timekeeping, and the science of horology.
• Horology.com - Horology is the science of time, timekeeping and timekeepers. Organized collection of links to horological websites globally.
• 24 hour analog clocks - The 24 hour analog clock and watch site. History, software, and the places to find clocks with 24 h dials.
• How Stuff Works: Time - Complete five-part explanation of time and how it is measured, including information about clocks, time zones, calendars, BC and AD.
• How The Days of the Week Got Their Names - A short history of the week and each day of the week.
• Jens Olsen's Astronomical Clock - Description of the restoration of Jens Olsen's Astronomical Clock, a masterpiece in Copenhagen City Hall that consists of 15.448 individual parts.
• Leap Year Calculation for Year 2000 - A response to a VMS problem report giving a detailed explanation of why 2000 is a leap year.
• Louis Essen - Autobiography of the physicist who built the world's first operational atomic clock.
• Ludwig Oechslin - Curator at the Musée International d’Horlogerie (international watch museum) in La Chaux- de - Fonds, Switzerland. He has designed some of the most complex wristwatches in history.
• Mark Frank's Home Page - Website showing the restoration of a french flat bed tower clock in great detail, step by step, as well as other information and links of tower clock sites.
• National Association of Watch and Clock Collectors - Organization of watch and clock enthusiasts.
• On Time - The Smithsonian Institute's exhibition on the changing ways we have measured, used, and thought about time over the past three hundred years.
• "Orologio" at the St. Mark's Square Tower, Venice - Antica Orologeria Zamberlan - Website of Antica Orologeria Zamberlan, Italy. Includes technical and historical explanation of the restoration and controversy of the "Orologio" Tower at St. Mark's Square, Venice.
• Pocket Horology - National chapter of the NAWCC dedicated to collaborative research on the history and horology of pocket watches.
• UNITAS Reference Site - UNITAS wristwatch and pocketwatch movements from 1898 to the present.