Don Casey - Dragged Aboard Dragged Aboard by Don Casey
A Cruising Guide for the Reluctant Mate


      

Other books by Don Casey
| Home | Mailing Lists | Bookstore | Weather | Tide Predictions | Bowditch |

Re: Mendoza's method for clearing lunars.

From: Frank Reed (no email)
Date: Wed Aug 04 2004 - 13:51:16 EDT

  • Next message: Zorbec Legras: "Re: Clarification of Question regarding LAN"

    George H wrote:
    "Then something funny happens. At the next value of lunar distance (which is
    95deg) all the rows show a sudden jump in the value of the correction, by 20
    seconds or nearly so, which is completely unphysical and could never happen in
    that way in real life. Then, as the lunar distance increases further, these
    values in succeeding columns gradually fall, in some cases to near-zero."

    FWIW:
    In Norie at the beginning of the tables, he has an explanation and
    description of each. For Table XXXV, after describing it generally and giving an example
    of its use, he writes:
      "This table is somewhat altered from the original when the distance is
    above 90d (the seconds being the complement to 20 of those formerly given) in
    order to adapt it to an easy and general method of clearing the distance by Joseph
    de Mendoza Rios, Esq. F.R.S. When his method is used, the seconds are to be
    taken out with the apparent distance at the top or bottom, and the moon's
    correction and difference of corrections in the side column."

    Also note that because of the cotangent of the distance in the calculation of
    this quantity, the quadratic term (table XXXV correction) is effectively zero
    for lunar distances between 78 and 102 degrees.

    Frank R
    [ ] Mystic, Connecticut
    [X] Chicago, Illinois


  • Next message: Zorbec Legras: "Re: Clarification of Question regarding LAN"



    | Home | Mailing Lists | Bookstore | Weather | Tide Predictions | Bowditch | Trawlerworld |