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    Re: Dennert & Pape MHR-1 Dennert & Pape MHR-1 HR-2
    From: Hewitt Schlereth
    Date: 2013 Jan 27, 18:25 -0800

    Brad -
    
    I will defer to Wolfgang, but my translation of
    
    Bei stundenwinkel und deklination zwischen 0 und 0 20 sowie bei
    stundenwinkel 90 ist der Hohenrechenschieber nicht zu verwenden
    
    is:
    
    For hour-angle and declination between 0 and 0 20' as well as for hour-angle 
    of 90, the altitude slide is not to be used.
    
    The two dots above the o are called an umlaut (Höhenrechenscheiber). The ö 
    sound is made by shaping your lips as though you were going to say 'oh', then 
    trying to say 'ee'.
    
    Hewitt
    
    Sent from my iPad
    
    On Jan 27, 2013, at 4:11 PM, "Brad Morris"  wrote:
    
    > Hi Gary
    > 
    > On the inner tube of my MHR1 (noted as tube II in the German instructions &
    > also the scale upon which we set the declination), the minimum angular
    > dimension is 20 min (179 deg 40 min).  At the other end of this same scale
    > I find 89 deg 40 min (90 deg 20 min).
    > 
    > Tube I (outer tube, upon which in the first step we set zero, or in the
    > third step, upon which we set azimuth) starts at zero.  The other end of
    > tube I is marked 89 deg 40 min (90 deg 20 min).  The double markings begin
    > at 35 deg (145 deg).  Below 35 deg, there is only a single mark, obviously
    > just due to limited room.
    > 
    > I thought to mention this as your email indicates that the smallest angular
    > dimension on this scale is 30 min.  Not true for mine.  I simply don't know
    > about others.
    > 
    > There ARE special instructions (in German) for when "stundenwinkel" (t)
    > and "deklination" are between 0 and 0 deg 20 min.  I cannot read German.  I
    > include the text following.  All typo's are mine.
    > 
    > Bei stundenwinkel und deklination zwischen 0 und 0 20 sowie bei
    > stundenwinkel 90 ist der Hohenrechenschieber nicht zu verwenden.
    > 
    > The first 'o' in Hohenrechenschieber has the two dots above it.
    > 
    > Regards
    > Brad
    > On Jan 27, 2013 6:39 PM, "Gary LaPook"  wrote:
    > 
    >> ------------------------------
    >> Do you have any actual instructions for using your MHR-1 for dealing with
    >> the special case when the declination is less than the lowest  declination
    >> marked on the tangent (or co-tangent) scale, 20' for the Bygrave and 30'
    >> for the MHR-1 and 50' on my flat Bygrave? I have never been able to find
    >> instructions for this situation. I am attaching a description for the use
    >> of this instrument (in French) which says it is "inutilisable" for this
    >> situation and the original Bygrave instruction manual is silent as to this
    >> situation, also attached.
    >> 
    >> I came up with a method of dealing with this situation and it is posted on
    >> my website at:
    >> 
    >> 
    https://sites.google.com/site/fredienoonan/other-flight-navigation-information/modern-bygrave-slide-rule
    >> 
    >> (In my notation "W" is the same as "y" in Bygrave's notation and "x" on
    >> the MHR-1.)
    >> 
    >> "When declination is less than one degree you can't begin the computation
    >> the normal way to find "W" because you have to start the process with
    >> declination on the cotangent scale and this scale doesn't extend below 1º.
    >> So in this case you just skip the computation of "W" and simply set "W"
    >> equal to declination. Using this method you arrive at an azimuth that is
    >> not exact but is a close approximation and in the worst case I have found
    >> the azimuth is still within 0.9º of the true azimuth but most are much
    >> closer. If the declination is less than one degree and the latitude is also
    >> less than one degree, follow this procedure and also assume a latitude
    >> equal to one degree. After you have computed the Az you then follow the
    >> same procedure discussed above for azimuths exceeding 85º by interchanging
    >> the latitude and declination and then computing Hc which will produce an
    >> exact value of Hc."
    >> 
    >> Also see my prior post at:
    >> 
    >> 
    >> 
    >> http://fer3.com/arc/m2.aspx/Computing-azimuth-with-Bygrave-special-cases-LaPook-feb-2010-g11826
    >> 
    >> gl
    >> 
    >> 
    >> --- On *Sun, 1/20/13, Marc Giordan * wrote:
    >> 
    >> 
    >> From: Marc Giordan 
    >> Subject: [NavList 22013] Re: Dennert & Pape MHR-1 Dennert & Pape MHR-1
    >> HR-2 Cylindrical Slide LineRuler
    >> To: garylapook---net
    >> Date: Sunday, January 20, 2013, 11:08 AM
    >> 
    >> ------------------------------
    >> 
    >> Sir,
    >> I am French and also quite familiar with the use of the MHR 1 at sea (I
    >> used it for 2 atlantic crossings by sail)
    >> Would any one wish to be trained in using it, I am ready to help !
    >> The MHR 1 was bought by my father some 30 years ago at the flee market in
    >> Paris
    >> Yours
    >> Marc Giordan
    >> 26 rue de Paris
    >> 78560 le Port Marly
    >> (0033)675210703
    >> ----------------------------------------------------------------
    >> 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
    >> ----------------------------------------------------------------
    >> 
    >> View and reply to this message: http://fer3.com/arc/m2.aspx?i=122013
    >> 
    >> *Attached File: 122138.calcul de navigation, v2 
    (courante).pdf
    >> *
    >> *Attached File: 122138.bygrave manual.pdf
    >> *
    >> 
    >> View and reply to this message: http://fer3.com/arc/m2.aspx?i=122138
    >> 
    > 
    > 
    > 
    > 
    > View and reply to this message: http://fer3.com/arc/m2.aspx?i=122139
    > 
    > 
    
    
    
    

       
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