Analysis of the latitudinal data of Eratosthenes and Hipparchus

TL;DR

This paper examines ancient latitudinal data attributed to Eratosthenes and Hipparchus, testing their consistency and providing new explanations for inconsistencies using adjustment theory, while deriving additional insights from the data.

Contribution

It applies adjustment theory to ancient geographic data to identify inconsistencies and offers new explanations and numerical estimates related to Eratosthenes' and Hipparchus' measurements.

Findings

Identified inconsistencies in ancient data and attributed some to Strabo.

Explained differences in Hipparchus' data by data type and precision.

Derived a numerical value for Eratosthenes' obliquity of the ecliptic.

Abstract

The handed down latitudinal data ascribed to Eratosthenes and Hipparchus are composed and each tested for consistency by means of adjustment theory. For detected inconsistencies new explanations are given concerning the origin of the data. Several inconsistent data can be ascribed to Strabo. Differences in Hipparchus' data can often be explained by the different types and precision of the data. Gross errors in Eratosthenes' data are explained by their origination from the lengths of sea routes. From Eratosthenes' data concerning Thule a numerical value for Eratosthenes' obliquity of the ecliptic is deduced.