A CITY LIGHTED WITH NATURAL GAS. 133 



vegetation," says Sir H. Davy, "here find a rich 

 repast, and grow in the utmost luxuriance, 

 forming a number of floating islands on its 

 surface." In certain districts of Asia Minor, the 

 springs are so charged with calcareous matter 

 as to deposit it in extraordinary quantities. 

 It is said by a traveller into those regions, that, 

 in order to make stone fences round the gardens 

 and vineyards of Hierapolis, it was only neces- 

 sary to conduct the water of such springs into 

 narrow channels, and they soon became filled up 

 with stone ! Even high roads are thus easily 

 laid down by other than human skill. When 

 such springs run over an eminence, they present 

 the curious appearance of a frozen cascade. 



An equally singular exhalation, also indicative 

 of decompositions deep in the earth, is that 

 of light carburetted hydrogen, or " coal-gas," 

 called by miners the " fire-damp." Being in- 

 visible, like carbonic acid, it is only to be 

 detected by its peculiar odour, and its inflam- 

 mability. When once a light is applied to these 

 streams of gas, they instantly inflame, and often 

 continue burning for years, until the supply 

 ceases. In the village of Fredonia, in the State 

 of New York, gas thus naturally produced is 

 collected and used to light the streets with ! 

 and also for heating and culinary purposes. At 

 the edge of the river above the rapids, at the 



