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First, bravo to Mr. Huxtable for his very lucid, learned, lunar distance
dissertation. I'll work the examples this weekend.

Looking forward to his part 3, I have a couple of thoughts about time sights.
First, have others besides myself noticed the frequency with which this term is
misused? In my mind, a time sight is a method of finding one's longitude by
solving the navigational triangle for meridian angle knowing codeclination,
coaltitude, and colatitude. I've noticed several writers using the term for
something else as the original time sight falls into disuse. I offer the
following as an example:

    From Marine Navigation by Richard R. Hobbs 3rd ed. pg. 455
    "When a very high degree of accuracy in the latitude line is required, many
navigators  construct a graph such as that shown in Fig. 25-2 (The figure shows
altitude plotted    against time during a meridian sight.) to assist in picking
the precise altitude of transit.    Such a series of sights is called a time
sight..."

I find this example interesting for two reasons. First, as mentioned previously,
this is not my idea of a time sight. Second, Hobbs doesn't go on to describe how
the resultant graphically determined time of meridian passage can be used to
find one's longitude to produce a lat-long fix from the noon sight. Granted,
it's not the best longitude fix, but if one goes to the trouble of graphing
one's noon sight observations one might as well use it to the best effect.

My second point for discussion is tables for solving real time sights. Bowditch
(pre-1995) offers a history of such tables, sometimes referred to as horary
tables, but I have never seen an example. Does anyone out there have an example
of any of these that they could scan and post? I thought it might be a nice
supplement to the discussion of finding longitude.

Chuck Griffiths


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