Fellow SML readers,
I recall reading somewhere that special
measuring individuals - probably slaves - had their stride length set by
a length of chain which would work very well if the surface was
reasonably flat...or did I dream it?
Tony Moss
On 28/07/2011 17:50, Roser Raluy wrote:
Dear all,
What I've heard about Eratostenes is that he paid someone to walk the
distance to Syene. He could make up easily the speed of a man walking
(about 6 Kms an hour) for a settled amount of days. He took mesures in
stadiums and there were different lengths of stadiums. If counted in
egiptian stadiums he only got 1% error which is fantastic speaking
about 3rd century BC. He had won the Olimpic Games and that's why he
was granted a "good job", the head of the Lybrary of Alexandria.
There's a you-tube film in spanish speaking about Eratostenes:
Fragmento del capítulo 1, "En la orilla del océano cósmico", de la
serie televisiva de divulgación científica Cosmos:
http://www.youtube.com/watch?v=QrDSfFvbYtI&feature=fvsr
Lots of sun
Roser Raluy
2011/7/28 Frank King<[email protected]>:
Dear John,
Yes, Eratosthenes was a great man who is
also noted for his sieve for extracting
prime numbers.
This may not be the right list for asking
about the performance of camels but I am
intrigued that it took a camel 50 days to
travel from Aswan to Alexandria.
The straight line distance is a little
over 500 miles and I can well imagine
that the route was far from straight.
Using "one day's travel" as a unit of
distance was pretty much the only way
of estimating differences in longitude
for many centuries after Eratosthenes.
A variant of this is used when training
people in the sport of orienteering...
You stand a trainee on open heathland
and ask him to stick his pencil in the
ground. Then using a compass you ask
him to pace out 100 steps north, 100
steps east, 100 steps south and then
100 steps west and pick up the pencil!
I have read that when Columbus was making
preparations for his well-known 1492 trip
he estimated the longitude of Japan relative
to Spain by noting how long it took to get
to Japan by the silk route using horses,
mules and so on.
Subtracting this from 360 he estimated how
many degrees of longitude Japan was west
of Spain and hence the distance. This
was about 3000 modern miles which is a
gross under-estimate caused by grossly
over-estimating how far east Japan was.
That said, he duly sailed about 3000 miles,
spotted land, and decided he had got to
Asia.
Some of this story seems plausible. It
would be good if it were also true!
All the best
Frank
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