Re: World's first computer may be even older than thought

On Jul 31, 2:30 pm, Mark Borgerson <mborger...@xxxxxxxxxxx> wrote:
In article <bbcae0a5-09a3-4a3d-b993-
b0f9fdd3d...@xxxxxxxxxxxxxxxxxxxxxxxxxxx>, jacklinthi...@xxxxxxxxxxxxx
says...

On Jul 30, 12:17 pm, Mark Borgerson <mborger...@xxxxxxxxxxx> wrote:
In article <fc55b980-606a-48f0-8ce8-
a9e459c8f...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, jacklinthi...@xxxxxxxxxxxxx
says...

On Jul 30, 12:49 am, William Hamblen <william.hamb...@xxxxxxxxxxxxx>
wrote:
On Wed, 29 Jul 2009 15:34:40 -0700 (PDT), Jack Linthicum

<jacklinthi...@xxxxxxxxxxxxx> wrote:
That never sail out of sight of land is a total myth, especially by
the 2nd C BC when this thing is supposedly built. Making noon sun line
observations with a known ideal for comparison would be useful in
doing the long distance haul. Also, I'm not sure how it was supposed
to work but one of the rivals for finding longitude in the 18th C was
"lunars". Again with a known standard, which we put in print until the
satellite stuff came into play, provides a check.

Imagine a cargo ship sailing just in daylight, putting ashore every
night, which would require unloading, setting up camp, cooking a
meal,sleeping, getting up, cooking a meal, reloading the ship and
setting sail.

Mathematical astronomy and shipboard instruments did not get good
enough to use lunar distances until the 18th century.  To figure your
longitude to one degree you need to know the position of the Moon to
better than 2 minutes of arc.  Newton developed in 1702 a lunar theory
that was the first to give predicted lunar positions with the needed
accuracy.  Hadley demonstrated his sextant in 1732.  Those were the
ingredients you needed for lunar distances.  Prior to that you
determined longitude at sea by dead reckoning.  Ancient sailors did
the same.  Experienced seamen who knew their trade routes would know
and use all sorts of details of currents and so on for navigation..  I
expect that they wouldn't lay up unless the weather was unfavorable.

A Google search turned up a book, "Homeric Seafaring" by Samuel Mark,
that looks interesting, if expensive (sixty bucks).

Bud

Pretty expensive book, $60 minimum and reaching into the multiple
100s. 256 pages.

The neolithic sailors used the stars, pretty good source in the
usually clear Med. A lot of their sailing was delivering wine and
foodstuffs so even anchoring over night seems a time waster.

The modern night sailors usually have shore lights and lighthouses to
use as navigation and piloting points.

The unloading of the cargo and subsequent reloading makes getting off
the beach easier. The Bronze Age ships had a built-in ramp on the aft
end to facilitate this procedure. Anyone who has launched a boat will
remember that Fat Uncle Louie does not get in the boat until it is
afloat.

If you move the unloaded boat up to the beach to the point
where you can reload with a ramp, the boat is going to be
stuck when you reload it, unless you do so at low tide.
A lot of the Med has a tidal range of about 1 foot---which
isn't going to be a great help and places severe constraints
on the schedule.

Unloading your cargo onto the beach at night would seem to
be an invitation to bandits ashore.  What did they fear
about being anchored 50 yards offshore that would motivate
them to do all the extra work?

Mark Borgerson

Implied in one of the bits was the motion wasn't conducive to sleep
and no room to stretch out. I also think you would need an anchor
watch in a windy area. The obvious need for relieving the body of
feces and fluid is not really enjoyed by all on a boat.

Those are good arguments for having the crew sleep ashore.  They don't
address any need to move the cargo ashore for the night.

Mark Borgerson

I get the theme of "drying out" ships when they are pulled ashore.
There are advisories to remove the drain plug and I would assume
anything on board would be also subject to drying out and would, in
turn, reduce that effect if left on board. Apparently Greek ships were
"loose" in the sense of not being fully watertight. One description of
a ship with a crew of 20 has 18 rowing and 2 bailing.

they may have been equipped with bilge drain plugs to facilitate and
drying out the boats after beaching. Hesiod mentions this.

http://www.artsales.com/ARTistory/Ancient_Ships/09_epic_poems.html
.

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