396 DOMAIN XII. VOLCANIC. 



various eminences they met in their course; 

 these streams united to form but two branches, 

 after having flowed over a space of four miles in 

 a very short period of time, in the night of 

 the 18th. 



" Nearly the whole surface of this lava was 

 covered with smoke, which issued from crevices 

 in the mass, and which increased in quantity in 

 proportion to its proximity to the crater ; much 

 smoke likewise arose from the crater itself. At 

 two in the morning, the thermometer of Reau- 

 mur stood at 19\ (6fii4 of Fahrenheit*). 



" On reaching the extremity of one of the 

 branches of lava recently ejected, I found it still 

 continued hot, and the heat was more sensible 

 as I advanced upon it. The thickness of this 

 stream did not exceed sixteen feet. Placing the 

 thermometer upon the drosses on the surface, 

 the mercury rose to 28 (82\ of Fahrenheit), 

 and had the guide allowed us to advance farther, 

 the heat would have been still greaterf. I 

 brought away some of the light drosses and 



* " Before I reached the lava, I made an experiment with the 

 new atmospherical electrometer of M. de Saussure; the air, not- 

 withstanding I raised my arm with the instrument as high as pos- 

 sible, exhibited no indications of electricity." 



f " The divergency of the balls of the electrometer, with which 

 I here made some experiments, did not exceed the fraction of a line ^ 



