lao GREAT MEN OF SCIENCE 



in London again, which now gave him the title of 'temporary 

 curator of experiments.' His duties were to attend to the 

 experimental demonstrations at meetings of the Society. 



In the year 1685 Papin was to learn that he had lost his 

 native country, since all protestants were banished from 

 France (Revocation of the Edict of Nantes). Many went 

 to Germany, and were welcomed there; thus the Landgrave 

 Carl of Hessen-Cassel invited a relative of Papin, and finally 

 Papin himself, to the University of Marburg, and Hessen 

 thus became a second home to him from that time forth for 

 almost twenty years. He also founded a family there. He 

 lectured on mathematics and parts of physics; but his main 

 efforts were directed towards realising several inventions 

 with which he was continually busy, above all a variation 

 of Huygens' powder motor, whereby hot steam was to be 

 used instead of the powder gases, which offered, as he 

 correctly realised, the advantage that a much completer 

 vacuum would be produced after cooling the contents of 

 the cylinder, and hence the air pressure would be made 

 better use of; also no residue would be left behind. This 

 was the fundamental idea of the present-day low pressure 

 steam engine. The Landgrave also, when first he received 

 Papin, showed great enthusiasm for such a machine, taking 

 as he did a lively interest in all inventions of Papin, no doubt 

 particularly because they were applicable to fountains, mills, 

 and mines. Unfortunately, Hessen, like the rest of Germany, 

 was kept in a state of perpetual warfare by Louis XIV, and 

 this continually diverted both the Landgrave's interest and 

 also the necessary financial means from Papin's undertakings, 

 with the result that they were often greatly hindered; this 

 was a repeated disappointment to Papin, the more so as 

 he was without means of his own of which he could make use. 

 Orders were also sent from time to time which meant 

 breaking off the work, or giving it an entirely altered direc- 

 tion. In these circumstances Papin published his plan for 



