Here is a diagram: I will assume that the sun was directly overhead in Syene (so no measurement) and he just needed to measure the angle at Alexandria and the distance between these two.

Each individual measure would have to be taken 10 units low in order to be exact (= N-1 more than in the incremental case), but then the total of N measures would read 10N low when re-measured.

If measurement errors and a linear trend of erosion were the only factors determining shoreline position, making predictions of future shoreline positions and their associated confidence intervals ...

ABSTRACT Statistical uncertainty in soil temperature and volumetric water content and related moisture and heat fluxes predicted by a state-of-the-art soil module [embedded in a numerical weather ...

Here is a diagram: I will assume that the sun was directly overhead in Syene (so no measurement) and he just needed to measure the angle at Alexandria and the distance between these two.