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: Clear side of horizon mirrors has reflecting properties.
    From: David Pike
    Date: 2020 Oct 16, 01:49 -0700

    One book, David, does mention it, on page 105 of "The Nautical Sextant", written, modestly, by me. For those who have not yet been wise enough to buy a copy, plain glass of refractive index of 1.55 at an angle of incidence of 10 to 15 degrees, typical of most sextants, reflects nearly 9 percent of the incident light.  Bill Morris

    Bill

    Well, after that sales pitch, I had to buy the book.  Kindle edition only, my bookshelves are full.  The only problem with Kindle is finding a page number.  How much you see seems to vary with the size of your PC/smartphone.  Please give more clues, e.g. Chapter, or between which diagrams.

    Actually, while searching to find which of your publications I’ve already downloaded and now lost inside my PC, I came across this on page 8 of ‘My Modern Sextant’ by Heath & Co,  price one shilling and sixpence.

    “While on the subject of Horizon Mirrors it may be pointed out that the reason there is an unsilvered portion is to enable exact contact to be made between the two objects observed; because the unsilvered portion partially reflects the reflected object.”  DaveP

       
    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