[Sherman Logan]

Yup. All educated people had known the earth was spherical for at least 2000 years.

Columbus underestimated the size of the earth, and overestimated the width of Asia.

The pundits at court were much closer to the actual distances involved and pointed out that Chris would run out of supplies long before he reached Japan.

They were quite right. If America hadn’t been in the way, CC and all his sailors would have died and the Crown’s investment would have been lost.

[Mycroft Holmes]

In 200 BC, travelers told the head of the Alexandria Library, Eratosthenes, about a well near present-day Aswan. The bottom of the well was lit by the sun at noon during the summer solstice. At that moment the sun was straight overhead. Eratosthenes realized he could measure the shadow cast by a tower in Alexandria while no shadow was being cast in Aswan. Then, knowing the distance to Aswan, it'd be simple to calculate Earth's radius.

Due to some erroneous assumptions he was off by about 15%. Not too shabby for the time.