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: Quartz article: reinstating celestial...
    From: Hewitt Schlereth
    Date: 2015 Oct 21, 20:07 -0700
    Greg, I made that table by slicing the sin/cos sections out of the larger table in vol 2 of the green Bowditch, so I had to keep the 9.-10 format. As you say, 100 years too late, but 1974 was way before I had my Radio Shack TRS-80. :-)


    On Oct 21, 2015, at 7:37 PM, Noell Wilson <NoReply_Wilson@fer3.com> wrote:


    Ding! That's the light finally coming on for me. I made a table of sin, Ln sin^5, Ln cos^5, cos but it was too abstract and 100 years too late. I also tried a set of log tables but didn't like flipping pages back and forth.

    I recently got a copy of Hewitt's Commonsense Celestial Navigation that solved the page flipping problem but had the 9.xxxx -10 format for the logs. I finally got around to speculating "Why not just drop the minus sign and the decimal point for the logs? As long as you keep the same system, you could use 30103 for the log sin of 30 instead of -.30103 or, adding 10, 9.6897."

    You sent me to H.O. 211 and there it is. Log sin 30 is 30103, log cos 30 is 6247 ( instead of -.30103 and - .06247). All that's missing for the standard sin/cos formula sight reduction are the values for sin and cos. Those could come from Hewitt's tables and format. That would allow a short set of tables and never getting more than one step removed from the sin/cos formula ( no intermediate K values as in HO 211). Hewitt's tables even list the 1' difference so you can interpolate as you get to the large changes near zero for sin or 90 for cos.

    The only downside I see is that it's still 100 years late.

    Regards, Noell

    View and reply to this message

    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