Euclid's Elements, Book 8 - Proposition 7

Propositions: If S1, S2, S3 ... Sn is a series of numbers in continuous proportion " where S2 is greater than S1, and Sn is a multiple of S1, then S2 is measured by S1 PDFs: https://github.com/sandy-bultena/Euclid/tree/master/Propositions/PDFs