Page "Porism" Paragraph 11

Robert Simson was the first to throw real light upon the subject.

He first succeeded in explaining the only three propositions which Pappus indicates with any completeness.

This explanation was published in the Philosophical Transactions in 1723.

Later he investigated the subject of porisms generally in a work entitled De porismatibus traclatus ; quo doctrinam porisrnatum satis explicatam, et in posterum ab oblivion tutam fore sperat auctor, and published after his death in a volume, Roberti Simson opera quaedam reliqua ( Glasgow, 1776 ).