Next message: Dan Allen: "Re: Lord Kelvin's lunars game (and an old joke)"
Sometimes today, navigation instructors will propose rather implausible
scenarios for learning celestial navigation as a backup, e.g. "for the day when
the enemy takes out the GPS". I was intrigued by a parallel story from 1898
of an excuse for learning the old art of longitude by lunars.
From "The Observatory", May 1898, noting that vessels are being captured as
prizes in the Spanish-American War, then underway, the author of a letter to
the journal wrote:
" I am credibly informed that the following device is, or has been, in
existence for encouraging the study of lunar distances by the youthful naval
officer who finds the study distasteful owing to the complexity of the
calculations and the apparent uselessness of the method (now that we have good
chronometers). The instructor points out that, although in times of peace, when
chronometers are plenty, lunar distances are at a heavy discount, yet in times of
war 'when you take a prize' (perhaps a delicate emphasis may be laid on the
'you') 'the captain of the magnificent vessel which surrenders will probably
throw his chronometers overboard, and then you will be puzzled how to safely
navigate the vessel into port. Of course there will probably be three
chronometers on your own ship, and if it is the first occasion of her taking a
prize, it may be that one of these can be spared for the officer put in charge.
But what is to happen in the case of the second and third etc. prizes? They
will have to be navigated home by lunar distances; and hence we will continue
the study of this most important matter.' "
And the author of the letter comments:
" There is considerable wiliness in this argument..."
That's for sure!
He's willing to wait for reports from actual prize captures to learn whether
this strange set of events might occur, but he adds:
"after all to throw overboard the chronometers of a ship you are to travel
in, though a prisoner, is rather like cutting off your nose to save your face."
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
