How did ancient scientists measure the size of the Earth?

[quddusaliquddus]

There are things that scientists of past had worked out - but we don't know exactly how they did so. If you know any post here please.

E.G.
I don't remember exactly, but it goes sumfin along the lines of an ancient Greek scientist who measured angles of shadows (or is that the duration in time) simultaneously in two places very far apart in Egypt during an eclipse- somewhere in the north and far south I tink. He used this to work out some measurement about the sieze of the Earth or latitudes or something. I'd assume he had a companion...but that could be wrong (?)
NO-NONE KNOWS HOW HE DID IT.

 

[Robert Zaleski]

You might be referring to Thales method for calculating the circumference of the Earth. www.mlahanas.de/Greeks/Eratosthenes.htm - 14k - May 23, 2004

 

[quddusaliquddus]

Thanks for that, but after reading it i found its not him. I'm sure whoever it was, did it in Egypt. I think there was definitely a case of simultaneous masurement. I am too lazy to think about the physics of it, but i think maybe he got sum1 to measure the shadowcast on a vertical rod while there was a full ecplise where he was. Using the shadow cast over there, he somehow calculated the latitudes or sumfin...

sorry about how crappy my descript is ... jus can't remember ... >:|

 

[quddusaliquddus]

People definitely DO NOT know how he did it ... that's y our physics teacher mentioned him to us

 

[Artman]

The Egyptians did many things that we cannot duplicate yet with similar tools. We don't know:

How the Egyptians moved and placed an 80 ton block of granite in the middle of the pyramids. There are theories, but none have been demonstrated successfully yet.

How they cut inside coved corners and drilled two foot deep 2" diameter holes in solid granite blocks using copper and wood tools (both softer than granite).

 

[quddusaliquddus]

Thanks for that Artman ... didn't know about the drillin ...

 

[quddusaliquddus]

I don't remember - but did the Mesoamerican people have an advanced calendar - one that would need use of telescope - but they didnt have a telescope? ... not sure about that one.

 

[Robert Zaleski]

Thanks for that, but after reading it i found its not him. I'm sure whoever it was, did it in Egypt. I think there was definitely a case of simultaneous masurement. I am too lazy to think about the physics of it, but i think maybe he got sum1 to measure the shadowcast on a vertical rod while there was a full ecplise where he was. Using the shadow cast over there, he somehow calculated the latitudes or sumfin...

sorry about how crappy my descript is ... jus can't remember ... >:|

You might want to get yourself a world atlas. Alexandria and Syene are located in Egypt.

 

[quddusaliquddus]

You're right. Hmm...was it Eratosthenes? ... it could be. The unexplained bit is probably the length he calculated using caravan trails.

 

[motai]

The Egyptians did many things that we cannot duplicate yet with similar tools. We don't know:

How the Egyptians moved and placed an 80 ton block of granite in the middle of the pyramids. There are theories, but none have been demonstrated successfully yet.

How they cut inside coved corners and drilled two foot deep 2" diameter holes in solid granite blocks using copper and wood tools (both softer than granite).

I believe another mystery is how they were able to get these massive monumental obelisks in place. There is a cool theory that someone used in NOVA that used gravity and sand. The obelisk is brought into position (at a large angle) and is cushioned on a large amount of sand positioned in a dug-out chamber. The sand slowly filters through an opening near the bottom of the chamber and gravity eases the obelisk into place.

 

[quddusaliquddus]

I don't get the obelisk one...

 

[Artman]

Another cool one is this map found in Russia. It was believed to be about 120 million years old covered with a relief map of the Ural mountains. The real interesting thing is that the map consists of three layers: the base is dolomite, the second layer is a diopside glass that can't be duplicated today and the whole thing is covered with a ceramic coating. The map is created in the glass layer and is, according to researchers, obviously done by machine. Also, relief maps are usually created today by observations done from the air, so how did they do this 120 million years ago?

Here is a link to the map.

Ancient Map

 

[quddusaliquddus]

cool. will check it out