IT is generally known that Newcomen was the first to produce a practical cylinder and piston steam engine, but there is a singular lack of evidence to show where he obtained his ideas. Various statements, some of them quite unsubstantiated, about the matter have been made, but little is known with certainty. No one has examined the subject with greater care than Mr. Rhys Jenkins, who at a meeting of the Newcomen Society on October 21 read a paper entitled “The Heat Engine Idea in the Seventeenth Century”. In this he impartially reviewed some of his own previous views and endeavoured to trace how the idea of applying heat for motive power might have been handed on from one projector to another in the course of the period 1612-1712. In turn, he referred to the writings and experiments of de Caus, David Ramsay, the Marquis of Worcester, Morland, Papin and Savery. To Papin certainly appears to belong the honour of producing a vacuum under a piston in a vertical open-top cylinder by the condensation of steam, and it may be Newcomen read a review of a book by Papin contained in the Philosophical Transactions of March 1697. Mr. Jenkins placed no credence on the story that Newcomen had been in correspondence with Hooke, as stated by Robison in the third edition of the “Encyclopaedia Britannica”, and this story must be omitted from the history of the steam engine, at any rate until documentary evidence is forthcoming.