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 > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
