I have uploaded another two chapters from Unit 1 of my second book. You are welcome to view them at https://www.academia.edu/11648843/How_to_Measure_the_Earths_Circumference
and at https://www.academia.edu/12064184/What_is_the_Size_of_the_Inhabited_World
“How to Measure the Earth’s Circumference” offers a simple way of comparing different attempts to estimate the circumference. It turns out that Columbus was not alone in his underestimation.
“What is the Size of the Inhabited World” examines various models to estimate the size of the habitable world. These estimations matched the traditional three-continent concept popular with medieval geographers.
The final chapter of this unit is going to come.