WITH NOTES. 



541 



its cover, with a jet in the centre, secured; on releasing 

 the spring, we have here a piston acting from below 

 upwards, to produce a fountain. 



John Baptista Porta, in his &quot; Spiritalia,&quot; quarto, 

 1606, gives a rude wood engraving, as here exactly 

 represented, a metal flask-shaped boiler, fitting the top 

 of a small furnace, while its neck proceeds through 

 the bottom of a cistern of water, within which there 

 is a syphon on the right hand side, and an aperture at 



the top through which the 

 cistern can be refilled. 

 By this arrangement, the 

 steam presses on the sur 

 face of the water, when 

 all is closed, except the 

 syphon, from which the 

 water will rush with in 

 creased velocity. 



In the 16th century, 

 motive and other ^Eolipile 

 were well known, and are 

 described and illustrated 

 by Vitruvius, Hero, and 

 other early writers. In 

 1606, Porta made a slight 

 advance, and John Rovin- 

 son, patentee of improvements in the manufacture of 

 iron, in his &quot; Treatise of Metallica,&quot; 1613, among other 

 necessary parts of his invention, describes the fol 

 lowing : u A new-devised vetible, round and hollow, 

 with a long spout, to be made of some mettall or potter s 

 earth, wherein water being put, and the same placed 

 on a fire, as it heateth, and the water evaporateth by the 

 spout, it maketh a continuall blast to kindle, or increase 

 the fire in furnaces, or fire-workes, and may be converted 

 to man?/ other excellent uses ; and same may be made in 



