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    Re: Ogura IJN
    From: David C
    Date: 2017 Aug 8, 21:22 -0700

    Peter wrote

    Some further discussion of Ogura's method and its relatives by Charles H. Cotter is on-line at http://www.cambridge.org/core/services/aop-cambridge-core/content/view/S037346330003393

    Thanks for the link. This raises a few points.

    I must take a global view of navigation. I admit that in the past I have approached the subject as an Anglophile. It is only  recently that Weem's Line of Position book has joined Lecky, Burdwood and  Inmans on my list of "must add to my collection". Ogura will also be added.

    I note that copies of Ogura's English edition were destroyed by fire and earthquake. Cotter does not mention the plates - presumably they survived and this is why the tables were reprinted so quickly.

    Cotter stated that the complexity of short tables increased if they provided azimuth as well as altitude.  He also said that this complexity was why short methods did not become popular. Something I do not understand is why the ABC tables did not become the default for azimuth. They are (in my opinion) quick and easy to use. Altitude by a simplified Dreisonstok and azimuth by ABC  tables seems to me (sitting in my armchair) to be a quick and easy way of working a sight. When I work a sight by cosine formula and calculator I usually pull out Norie to determine the azimuth.

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