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
    Name or NavList Code:
    Email:
       
    Reply
    Re: Measuring Dip in the 18th Century
    From: Greg B
    Date: 2013 Dec 27, 19:01 -0500
    Hi guys,
            Please help me understand the 'instrument time line'. What is the angular resolution of a cross-staff or back-staff?
    I always thought it was about +/- a degree, and if thats true why would you care about 1 arc minuet?
    I always thought the first sub degree instrument was the octant.
    ~Greg

    On 12/27/2013 06:04 PM, Alexandre Eremenko wrote:

    I am reading a book about Thomas Harriot (an outstanding British mathematician) In 1595, he wrote "Instructions for assisting the navigators of Sir Walter Raleigh's voyage to Guiana.
    The instructions contain the following dip table
    1 3'
    2 4'
    3 5'
    4 5'
    5 6'
    6 6'
    7 7'
    8 7'
    9 8'
    10 8',
    where the left column is the height in PASE's; according to the authr of the paper,
    1 pase=5 feet.

    The paper also has a reference to an early Portuguese source: Pedro Nunes, De arte ratione navigandi libri due (Coimbra, 1546).

    The article I am reading is Jon V. Pepper, Harriot's earlier works on mathematical navigation: theory and practice.

    Gary: have you received my request sent off-the-list?
    ----------------------------------------------------------------
    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
    ----------------------------------------------------------------

    : http://fer3.com/arc/m2.aspx?i=125973


       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

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

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

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

    Email Settings

    NavList ID 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