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
    MHR1 dimensions and details
    From: Wolfgang Hasper
    Date: 2009 Sep 24, 21:59 +0200

    Does anybody have more pictures with details of MHR1, detailed dimensions 
    etc.? (more than contained in RvR's and Svarovski's papers)
    I am thinking of making some cad drawings and/or a digital model.
    In the end this may lead to a (functional, not fac-simile) replica maybe using 
    rapid prototyping techniques. (one reason is that it seems really difficult 
    to get hold of suitably sized tubes.)
    Does anybody have additional information on the locking mechanism? My guess 
    is, that there must be a knee-lever mechanism across the diameter of an 
    end-cap in the inner tube (knee-lever is self-locking, can be actuated with 
    just a slight turn on the knob) that is forced aginst the inner wall of the 
    intermediate tube. 
    Couldn't anybody in possession of such a device go to the nearest airport and 
    ask security to scan it ;o)  ?
    
    Wolfgang
    
    
    
    
    
    > I was in London last month and made arrangements (with the assistance of
    > Geoffrey Kolbe, thanks again) to see the examples of Bygraves and the HR
    > series held by the Science Museum and by The National Maritime Museum. I
    > attach two photos showing my hot little hand holding examples of each.
    >
    > The Bygrave I saw was a Mk II serial number 105, the same one shown in Van
    > Riet's paper. I measured the diameters of the scales, actually their
    > circumfrances using a tape measure, and my numbers are very slightly
    > different than his. I believe my measurements are accurate to one-half of a
    > millimeter.
    >
    > The circumfrances were:
    >
    > Cotan   174mm
    > Cos     187mm
    > Cursor tube 203mm
    > Knob at bottom of cosine scale  207mm
    >
    > Dividing by Pi gives diameters of:
    >
    > Cotan 55.4mm
    > Cos   59.5mm
    > cursor 64.6mm
    > Knob 65.9mm
    >
    > I am attaching two photos showing two details of the construction. One is a
    > photo of the cotan scale showing that it was printed on paper and then
    > wrapped around the tube. You can see the gap that has developed over time.
    > The second shows a detail of the long pointer, it is bent downward to be
    > near the cotan scale to eliminate parallax.
    >
    > The National maritime Museum has three examples of the HR1 and one example
    > of the larger HR2. The three HR1s were in cans and the HR2 had a cover and
    > was obviously meant to be mounted on a desk. The first two HR1s I examined
    > were in perfect shape but the third one (the one I am holding in the
    > picture) was in poor shape. I am attaching two photos of the HR2 one
    > showing the scale revealing the same construction method used in  the
    > Bygrave, a paper scale glued around a tube.
    >
    > It was a thrill for me to actually see these instruments. My first
    > impression was that they are very big compared to the one I constructed
    > which is only one and a half inches in diameter.
    >
    > gl
    >
    >
    > 
    File:


    >
    File:


    >
    File:


    >
    File:


    >
    File:


    >
    File:


    >
    File:


    > > > -- Wolfgang Hasper Beckstra�e 87 64287 Darmstadt 06151-4289333 --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To unsubscribe, email NavList-unsubscribe@fer3.com -~----------~----~----~----~------~----~------~--~---

       
    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