Welcome to the NavList Message Boards.

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Time up for the leap second?
    From: Richard B. Langley
    Date: 2012 Jan 17, 22:59 -0400

    A similar approach is used to sync up the clock in the tower at
    Westminster ("Big Ben" -- although that is really the name of the
    largest bell in the tower) on the evening of the leap second by
    gradually taking off some of the old pennies in a tray near the top of
    the clock's pendulum.
    
    -- Richard Langley
    
    Quoting Frank Reed :
    
    > You may reasonably imagine that this is easy and computers have it
    > all programmed in, but it's an illusion. Computer code for
    > networking has developed in an organic fashion. At the end of 2008,
    > the folks who manage Google's servers chose to skip the leap second
    > in the proper sense, and instead they inserted 1000 one-millisecond
    > delays (equivalent) during the course of the day on December 31,
    > 2008. As their official blog described it:
    > "The solution we came up with came to be known as the 'leap smear.'
    > We modified our internal NTP servers to gradually add a couple of
    > milliseconds to every update, varying over a time window before the
    > moment when the leap second actually happens. This meant that when
    > it became time to add an extra second at midnight, our clocks had
    > already taken this into account, by skewing the time over the course
    > of the day. All of our servers were then able to continue as normal
    > with the new year, blissfully unaware that a leap second had just
    > occurred. We plan to use this 'leap smear' technique again in the
    > future, when new leap seconds are announced by the IERS."
    >
    > -FER
    >
    > ----------------------------------------------------------------
    > NavList message boards and member settings: www.fer3.com/NavList
    > Members may optionally receive posts by email.
    > To cancel email delivery, send a message to NoMail[at]fer3.com
    > ----------------------------------------------------------------
    
    
    
    -----------------------------------------------------------------------------
    | Richard B. Langley                            E-mail: lang@unb.ca         |
    | Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/ |
    | 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/       |
    -----------------------------------------------------------------------------
    
    
    
    
    

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
    Email:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site