Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Leap seconds at Big Ben.
    From: Richard M Pisko
    Date: 2009 Jan 04, 00:27 -0700

    On Thu, 01 Jan 2009 12:32:55 -0700,  wrote:
    > On the home-made regulator clock whose picture I include as an
    > attachment, I use increments of 100 milligrams and can achieve a rate of
    > two or three seconds a month, but as the brass-compensated Invar
    > pendulum rod is not (yet) correctly compensated, the rate changes with
    > the season.
    Where is the pendulum weight fastened to the invar rod; and how?
    I was wondering . . .  if the rod were to have male threads at a certain
    pitch, say 20 threads per inch on a 1/2 inch diameter rod, and the brass
    cylinder were to have female threads of say 3/4 by 20 tpi, there is room
    for a short sleeve about 1/8 inch thick to hold the rod and pendulum
    weight together.  The sleeve would be threaded inside and out at the same
    20 tpi to fit the rod and weight, and a couple of notches at the lower end
    would allow the sleeve to be screwed up or down by a hollow shaft
    screwdriver.  The relative location of the brass weight and the rod would
    remain the same, but the amount of temperature compensation would change,
    I think.  For example, as the sleeve is screwed downward, the top end of
    the brass weight would remain in the same position relative to the rod
    initially, but would move upward more as the temperature increases.  The
    change in position of the sleeve (lowered) would have to be compensated by
    adding a weight in your tray, I believe, or by screwing the brass weight
    upward a bit on the sleeve and rod.  Is this what you did?  If the Invar
    rod length were actually invariable in a moderate temperature range, I
    think placing the sleeve in the mid point of the brass cylinder would be a
    good start experimentally, but where would theory suggest?
    What a fascinating assortment of projects you have.
    Richard . . .
    Using Opera 9.2.4 after the "Dog" died
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
    To unsubscribe, email NavList-unsubscribe@fer3.com

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    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 Settings

    Posting Code:

    Custom Index

    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