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    Re: The Bygrave
    From: Hanno Ix
    Date: 2009 Jun 30, 11:31 -0700

    Could you give us a detailed description of the MHR -1 + plus perhaps a number of pictures?


    Hanno Ix

    --- On Tue, 6/30/09, Ronald van Riet <ronald{at}van-riet.nl> wrote:

    From: Ronald van Riet <ronald{at}van-riet.nl>
    Subject: [NavList 8893] Re: The Bygrave
    To: "NavList" <NavList@fer3.com>
    Date: Tuesday, June 30, 2009, 2:44 AM

    Yes, I do have both a Bygrave and an HR1 (am I the only one to own a
    copy of both?)

    As far as rarity (rareness?) of these go, here are the numbers I know
    to exist:

    Bygrave: 6 in private collections, 2 in museums.

    HR1: 3 in private collections, 3 in museums.

    MHR1: 9 in private collections, 2 in museums, 1 known to have been in
    private hands but missing since this person died.

    HR2: 1 in private collection, 1 in museum, 1 known to have been in
    private hands but missing since this person died.

    Anybody owning one of these, please contact me off list so I can
    update my document on these position line slide rules. Please include
    serial numbers if possible



    On Jun 29, 8:00 pm, Brad Morris <bmor...{at}tactronics.com> wrote:
    > Hi Douglas
    > I actually DO have an MHR-1 (German Version of the Bygrave).  Get ready to hear the collectors moaning, I USE it, without gloves.
    > It is a joy to use.  The solution of Az and h are just as fast as can be.  The MHR-1 doesn't suffer from the actual Bygrave problem where the scales slipped relative to one another.  Weighs alot less than HO229 and much smaller too.
    > Gary's Flat Bygrave is even lighter and smaller, essentially  two sheets of mylar.  You may wish to try it.  It really does work and give the feel without selling your house to own one. Or the my Visual Bygrave, which extends the scales perfectly from 0 to 90 degrees, far beyond what either physical realization can do.
    > I do believe that Ronald has a sample of actual Bygraves//MHR-1's
    > They do appear on eBay from time to time.  Be prepared to spend a bundle.
    > Best Regards
    > Brad
    > ________________________________________
    > From: NavList@fer3.com [NavList@fer3.com] On Behalf Of douglas.de...{at}btopenworld.com [douglas.de...{at}btopenworld.com]
    > Sent: Monday, June 29, 2009 12:11 PM
    > To: NavList@fer3.com
    > Subject: [NavList 8877] Re: Star-star distances for arc error
    > I should have also commented:
    > I would dearly like to get my hands on a real Bygrave slide rule or the German equivalent to play with and try it 'for real'; (hands covered in white gloves to preserve it of course).
    > I have only seen one example and that was in the Aviation museuum in Hendon. It looked in poor condition too.
    > From a programme supplied by Dr. Kolbe I made one with a cardboard tube and a sliding clear outer ("cos") scale just to try the operations for the fun of it.  It proves the principle but is near impossible to use as the two scales become so confusing one on top of the other.
    > I have not yet tried using different colours for the different scales to see if it is then possible to use it more successfully.
    > Interesting to speculate if Mr. Bygrave tried this and rejected it as being impracticable, reverting to the separated scales of a conventional cylindrical slide rule and movable cursor to reduce confusion possibilities.  Probably not.
    > What I do wonder is what happened to all these Bygrave slide rules - and the German ones?  There must have been hundreds made and yet now they are incredibly rare it seems.  The Air Ministry must have had boxes full of them somehwere on the shelves of some nondescript warehouse in teh middle of nowhere.  It is nice to contemplate that perhaps they are still there? ..
    > ...though much more likely thrown out by some idiot who was following orders to throw away "that rubbish over there on the shelves released from the Air Ministry inventory as uselss and obsolete!
    > Vandals!
    > Douglas Denny.
    > Chichester.  England.
    > Douglas Denny.
    > Chichester.  England.
    > "Confidentiality and Privilege Notice
    > The information transmitted by this electronic mail (and any attachments) is being sent by or on behalf of Tactronics; it is intended for the exclusive use of the addressee named above and may constitute information that is privileged or confidential or otherwise legally exempt from disclosure. If you are not the addressee or an employee or agent responsible for delivering this message to same, you are not authorized to retain, read, copy or disseminate this electronic mail (or any attachments) or any part thereof. If you have received this electronic mail (and any attachments) in error, please call us immediately and send written confirmation that same has been deleted from your system. Thank you."

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