h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Hi EYG!!!

As you say, it was Eritosthenes who calculated the size of the Earth.

He worked in the Great Library in Alexandria where he read a scroll pointing out the phenomena of the sunlit well, and the fact that vertical sticks cast no shadows. Where this happened was in the town of Syene, far to the south of Alexandria.

Through experimentation on the Summer Solstice (the only time this happened) he discovered that the angular distance between the two towns was 7 degrees. Eritosthenes figured this to be one fiftieth of a section of a circle.

As you correctly say, he got someone to walk to Syene and back to discover the distance between there and Alexandria, and the answer came back (converted into modern measurement) as 500 miles, or 800 kilometres.

Multiply each by 50 and you get 25,000 miles, or 40,000 kilometres.

Very, very close!!! Today we say 24,800 miles, or about 39,200 kilometres!!

Sorry I cannot give QI points retrosectively!!!!!




GT

Hi GT,

that is a useful and informative reply but, unfortunately, it has ended up in my 'Personal Space' page, where few others are ever going to see it.

I would very much appreciate it if you could cut and paste a copy of your post into the QI thread of the same name.

regards, (looking forward to next round of questions, actually)


EYG

EYG

I deliberately posted to you as full explanation had already gone onto QI.

It was purely a respectful reply to you as you had posted to a 'dead' thread.



GT

You can tell I'm new around here, can't you? I admit the thread is dead as far as the points are concerned but I see no reason why the conversation should come to an end, at least not while we are waiting for fresh questions, which means old threads are still on view. Also, if someone searches for Eritosthenes now, will my personal space show up in their search results? If so, I'd rather that didn't happen. Basically, this is just my clumsy way of saying that, if I post a reply to an existing conversation, I would prefer to see replies to my post *in that conversation*. This makes navigating up and down the thread in question that much easier for me. Speaking of which .... http://www.bbc.co.uk/dna/h2g2/brunel/F7180006?thread=6774986 . EYG