About 'Time'

Swedish botanist Carl von Linné observed that flowers open and close at certain times of day. In 1745 he proposed a flower clock to complement the then used sundials. It would indicate the time with an accuracy of half an hour, even when sky is overcast. This dial was painted by Ursula Schleicher-Benz in 1948.

The Time is a fascinating topic. Several people in the Internet community publish documents about the definition, measurement and calculation of time. Here are some entries to a wealth of information:

The term 'Time' requires explanation. The document A Few Facts Concerning GMT, UT, and the RGO by Richard B. Langley is a good discussion of different terms of time.

There is a comprehensive 'note' (sheer understatement) about The Science of Timekeeping, written by three well reputated physicists (David W. Allan, Neil Ashby, Clifford C. Hodge).

You may proceed with reading RFC-1305 by David L. Mills, the definition of NTP (avalaible in PostScript and pdf).

Visit the International Earth Rotation Service (IERS) in Paris, France. The guys who keep the earth rotating, you think? Not exactly. They make the leap seconds we are all aware of. Not?

A Summary of the International Standard Date and Time Notation by Markus Kuhn is worth reading not only for formally predisposed persons.

The Time of Internet by Fabrizio Pollastri lists 'Information and curios, news and notions, Internet sites and services about time measurement'.

Not mentioned the omniscient 'Home of the Network Time Protocol' yet? You already saw it.

Look at the home page for the book specified below. It has a long list of links too.

If you are really interested in time and date definitions and calculations, including holidays, you should read this fine book:

Dershowitz, N. and E.M. Reingold:
Calendrical Calculations.
Cambridge University Press
Cambridge (UK) / New York / Melbourne
Second edition, 2000
ISBN 0-521-77167-6 (hardcover) or
ISBN 0-521-77752-6 (paperback)

Some of the calculations defined here are used in the NTP daemon software. You will find a comprehensive bibliography. The authors established a home page for the book to facilitate communication.

There is a lot of software concerning Time in the Internet, both freeware and shareware. Again, look at the home page for the book specified above. There are several links to software too.

Besides the NTP daemon software the 'Home of the Network Time Protocol' maintains a list of links to many software sources. A DCF77 daemon is in the xntp distribution.

Software special to DCF77 and Linux you will find listed on a page of Harald Milz who will link you to some sites in Germany and around.

Poul-Henning Kamp in Denmark managed to get state of the art performance on a FreeBSD machine using a standard motherboard and a cheap GPS receiver.