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: telegraphic longitude article
    From: Fred Hebard
    Date: 2003 Dec 26, 21:05 -0500

    I regret not having read Chauvenet's manual, which I expect covers all
    this (and hope I can understand the book when I receive it!).  But, how
    would this technique allow the transit times to be cancelled.  I
    apologize for my lack of comprehension.
    Fred Hebard
    On Dec 26, 2003, at 7:04 PM, George Huxtable wrote:
    > I doubt if there were relays involved in the telegraphs for that
    > purpose at
    > that time.  Observer A would tap a key when a star crossed (one of
    > many)
    > hairs in his transit telescope, and then a current pulse would flow
    > down
    > the wire. At both ends A and B of the wire would be a chronograph,
    > which
    > was a recording galvanometer, which drew a trace of the resulting
    > current-pulses. A single master-clock, somewhere in the system, added
    > timing pulses to the trace, at the two ends. Times were recorded at
    > both
    > ends when a star passed over observer A, and again when the same star
    > passed over observer B.
    > This technique allowed the transit time of the elactrical signals to be
    > cancelled out.

    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