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Archiver > Dutch-Colonies > 2002-08 > 1029117462


From: "roland elliott" <>
Subject: Re: [D-Col] Blaeu atlas & other historic maps
Date: Sun, 11 Aug 2002 18:57:54 -0700
References: <v04210102b97cc73fbda5@[171.66.164.6]>


Ptolemy was so far ahead.He had levels,measure sticks.and with them he had
holes dug every 6 miles[our measurement] North and a man with a hour glass
to clock and send a runner when the sun hit the bottom of the hole,he came
up with 60 degree latitude and the circumference of the earth.Longitude
needed Harrison's clock except above the 20th Lat. where by the Vikings made
a rudimentary Sextant to determine Longitude which was extended southerly
with some closeness until Harrison's Gimbaled clock.
----- Original Message -----
From: "Priscilla Hexter" <>
To: <>
Sent: Sunday, August 11, 2002 19:04
Subject: [D-Col] Blaeu atlas & other historic maps


> Hello List,
> Perhaps the following might shed light on Howard's questions about
> historic maps:
> The convention of locating north at the top, south at bottom, east
> to the right and west to the left on European/American maps is a
> relatively recent one. During the middle ages and up through the
> 16th century European maps were drawn "every which way" often having
> to do with the size and shape of the area to be mapped relative to
> size and shape of available paper or vellum, and whether the map was
> to be bound in a volume or issued as a single sheet.
> The cartographer and astronomer, Ptolemy, plotted the zero-degree
> of latitude at the Equator in the 2nd century A.D., on the authority
> of predecessors. He felt free, however, to plot his prime meridian,
> the zero-degree longitude line, where he wished. He chose to run it
> through the "Fortunate Islands," known to us as the Canary & Madeira
> Islands, off the NW coast of Africa. Later European mapmakers rather
> frequently moved the prime meridian - to the Azores, Cape Verde
> Islands, Rome, Copenhagen, Jerusalem, St. Petersburg, Pisa, Paris and
> Philadelphia! Finally, in the 18th c. it settled down at London, or
> more precisely, at Greenwich where it remains. Hence the differences
> in the 0 degree point for longitude you noted on some of the 16th and
> 17th c. maps. Additionally, too, in the 18th century, John Harrison,
> an English clockmaker and mechanical genius, finally determined a
> workable method of calculating longitude while at sea. (A nice book
> about Harrison's life and work, Longitude, by Dava Sobel, was publ.
> in 1995.)
> Best regards,
> Priscilla Romans Hexter
>
>
>
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