112 LECTURES TO SCIENCE TEACHERS. 



sion to the history of the steam-engine, and you will see by 

 the models on the table that that is the conclusion to which 

 I have already come. Therefore I trust you will bear with 

 me while I occupy some portion of your time in going into 

 the historical part of our subject. 



I begin with Papin, who, according to his pamphlet, 

 published in 1707 (in consequence, as Belidor says, of a letter 

 written from London in 1705), states that in 1698, he, Papin, 

 made experiments with his steam-engine, the engine which, 

 no doubt, is so well known to most of you. In the collection 

 there is a cylinder (No. 2007) which is said to be a portion of 

 one of Papin's machines. How that can be, I am at some loss to 

 understand, inasmuch as the cylinder is open at both ends, and 

 at one end only is there a flange or any provision for making a 

 reclosure. The other end, it seems to me, must have always 

 remained entirely open, and therefore I do not know how it 

 could have been employed in any way in Papin's apparatus, of 

 which there is an elementary diagram upon the wall. From 

 this diagram you will see that Papin had invented that which 

 may be called a high-pressure water-raising engine ; but mere 

 water-raising was not the limit (in intention, at least) of 

 Papin's scheme, inasmuch as he proposed an alternative use 

 of the pressure in the air-vessel, viz.: the production of 

 a powerful jet of water from the outlet cock, which jet should 

 impinge on the vanes of a water-wheel, and thereby produce 

 rotary motion. Whether rotary motion was ever so obtained 

 does not appear to be recorded. Although, as I have said, 

 no doubt Papin's engine is well known to most of you, it will 

 be well briefly to describe it. It consisted of a boiler, from 

 which a steam-pipe proceeded to the upper part of a vertical 

 cylindrical pressure-vessel, which could be filled with water 

 from any source of supply above it ; then, the inlet of the 

 water being stopped by the turning of a cock, the steam from 

 the boiler could, by the turning of another cock, be admitted 

 to press upon the water in the vessel and to drive it out- 

 wards through a check- valve into an air-vessel, whence it was 

 to rise to the desired height. To diminish the condensation 

 of steam, a floating diaphragm (which some call and, to my 

 mind, improperly call a piston) was provided to prevent the 

 actual contact of the steam and the water. 



At about the same time Savery, (as we know) in England, 

 was not merely making experiments but was bringing into 



