486 



On the Construction of Kitchen 



plates of metal will allow it to be pressed inwards or 

 drawn outwards without injury, much more than will 

 be necessary in order to give room for the expansions 

 and contractions of the tubes. 



Hence it appears that, by this simple contrivance, 

 steam may be conveyed to any distance, however great, 

 in closed metallic tubes, without any danger of injury 

 to the tubes from the expansions and contractions of 

 the metal. 



A short Description of a Contrivance which serves in- 

 stead of Safety-valves for a Steam Apparatus, which 

 is used for heating the Great Lecture-Room at the 

 House of the Royal Institution. 



The following figure, which represents a vertical 

 section of this contrivance, will give a clear idea of it, 

 and of the manner in which it acts : 



Fig- 95- 



a and b are two cylinders of copper, 6 inches in diame- 

 ter and 6 inches in length, placed in an erect position. 

 The cylinder a is closed both above and below; the 

 cylinder b is closed below, but is open above. 



