Aha. Thank you. I didn't knew this.
On Fri, Jan 9, 2015 at 8:32 PM, Richard B. Langley <[email protected]> wrote: > The secular change in the rotation of the Earth as related to the motion of > the Moon had been detected by 1695 by Edmond Halley. Suggested explanation > given by Emanuel Kant in 1754. Will send the Harold Spencer Jones paper on > this later today. The smaller, atmosphere-related fluctuations were > discovered in the 1930s (I think) using pendulum clocks. > -- Richard Langley > > On Friday, January 9, 2015, 9, at 3:23 PM, Pierpaolo Bernardi wrote: > >> Markus Kuhn writes: "The varying length of the day has been known for >> centuries but only became a practical concern (outside astronomy) with >> the invention of atomic clocks in the 1950s." >> >> Is this true? I though it was discovered only in the 20th century? >> From the context he refers to mean solar day, I understand. >> >> >> On Fri, Jan 9, 2015 at 2:24 PM, Tom Van Baak <[email protected]> wrote: >>> They were wise enough to ask Markus to write it; a nice balance between >>> popular and technical. They were kind enough to ask permission to use a >>> cesium clock leap second photo from my web site. "Not something you see >>> every day" indeed! >>> >>> https://theconversation.com/an-extra-second-on-the-clock-why-moving-from-astronomic-to-atomic-time-is-a-tricky-business-35970 >>> >>> Markus -- your LOD plot ends in 2011? >>> >>> /tvb >>> >>> _______________________________________________ >>> LEAPSECS mailing list >>> [email protected] >>> https://pairlist6.pair.net/mailman/listinfo/leapsecs >>> >> _______________________________________________ >> LEAPSECS mailing list >> [email protected] >> https://pairlist6.pair.net/mailman/listinfo/leapsecs > > ----------------------------------------------------------------------------- > | Richard B. Langley E-mail: [email protected] | > | Geodetic Research Laboratory Web: http://gge.unb.ca/ | > | Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 | > | University of New Brunswick Fax: +1 506 453-4943 | > | Fredericton, N.B., Canada E3B 5A3 | > | Fredericton? Where's that? See: http://www.fredericton.ca/ | > ----------------------------------------------------------------------------- > > _______________________________________________ > LEAPSECS mailing list > [email protected] > https://pairlist6.pair.net/mailman/listinfo/leapsecs _______________________________________________ LEAPSECS mailing list [email protected] https://pairlist6.pair.net/mailman/listinfo/leapsecs
