How was the circumferance [sic]
of the earth first ascertained.
I have not succeeded in finding out to a certainty...
[The unnamed writer goes on to explain two possible methods: one, by calculating from the convexity as seen at a measured distance in the ocean and then using geometry to arrive at the answer; and two, “by ascertaining the time the sun is in passing over any measured space on the equator” and calculating from that.]