Also Perry, on the way to the North Pole used a hand wound drum with a lead on a long wire to measure the depth of the Arctic Sea. Since this information was not known before him and was not measured again until fifty years later when we had submarines traveling under the ice, the accuracy of his data when compared with the new data also confirmed that he reached the pole.
gl
--- On Mon, 3/5/12, Lu Abel <luabel@ymail.com> wrote:
From: Lu Abel <luabel@ymail.com>
Subject: [NavList] Re: About time - Antarctica
To: "NavList@fer3.com" <NavList@fer3.com>
Date: Monday, March 5, 2012, 9:43 AM
With absolutely no expertise in the matter, I would speculate that knowing the water depth to several fathoms of accuracy would be enough, so that springiness of the line or a somewhat angular drop to the bottom would not be of utmost concern. I suspect these folks were trying to just get a general idea of the shape of the seabed, how far out the continental shelf extended, slope of the seabed (gentle dropoff or abrupt), etc on the shores of a basically unexplored continent.
Lu
From: Gary LaPook
<garylapook@pacbell.net>
To: NavList@fer3.com
Sent: Monday, March 5, 2012 9:27 AM
Subject: [NavList] Re: About time - Antarctica
Very much like using a hand lead line except it was a much heavier weight on a long wire which was on a motorized reel. This device was called a "deep sea lead."
gl
--- On Mon, 3/5/12, Bruce Pennino <bpennino.ce@charter.net> wrote:
From: Bruce Pennino <bpennino.ce@charter.net>
Subject: [NavList] About time - Antarctica
To: NavList@fer3.com
Date: Monday, March 5, 2012, 7:50 AM
Just finished reading The Storied Ice by Joan
Boothe. A very good overview book about all major explorations
of Antarctica; many references.
Anyway, Antarctica explorers had a longitude
problem. In 1926-27 the Discovery "was the first vessel in these waters capable
of receiving Greenwich time signals directly, and her men used the signals to
check longitudinal positions on the maps." Only Deception Island was
properly located.
Also,as the early explorers headed south ,they
measured water depth for various reasons. How did they measure depths of several
thousand feet with a drifting ship, angle of cable,
flexibility(springiness)?
Boothe gives a brief overview of Cook's
explorations....she says he was an extraordinary man.
Bruce Pennino
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