541 



PHYSICAL GEOGUAPHY. 



with the road for about fifty yards, when it vanished, probably from the failure of the 

 gas. The manner in which it disappeared was similar to that of a candle being blown 

 out." The ignis fatuus has not become so strange in various continental districts as with 

 us. We have the best account of it from Mr. Blesson, who examined it abroad with 

 great care and diligence. 



" The first time," he states, "I saw the ignis fatuus, was in a valley, in the forest of 

 Gorbitz, in the New Mark. This valley cuts deeply in compact loam, and is marshy on 



Ignis Futuus. 



its lower part. The water of the marsh is ferruginous, and covered with an iridescent 

 crust. During the day, bubbles of air were seea rising from it, and in the night blue 

 flames were observed shooting from and playing over its surface. As I suspected that 

 there was some connection between these flames and the bubbles of air, I marked durin^ 



7 O 



the day-time the place where the latter rose up most abundantly, and repaired thither 

 during the night ; to my great joy I actually observed bluish-purple flames, and did not 

 hesitate to approach them. On reaching the spot they retired, and I pursued them in 

 vain ; all attempts to examine them closely were ineffectual. Some days of very rainy 

 weather prevented farther investigation, but afforded leisure for reflecting on their nature. 

 I conjectured that the motion of the air, on my approaching the spot, forced forward the 

 burning gas, and remarked that the flame burned darker when it was blown aside ; hence 

 I concluded that a continuous thin stream of inflammable air was formed by these bubbles, 

 which, once inflamed, continued to burn, but which, owing to the paleness of the light of 

 the flame, could not be observed during the day. On another day, in the twilight, I went 

 again to the place, where I awaited the approach of night : the flames became gradually 

 visible, but redder than formerly, thus showing that they burnt also during the day : I 

 approached nearer, and they retired. Convinced that they would return again to the place 

 of their origin when the agitation of the air ceased, I remained stationary and motionless, 

 and observed them again gradually approach. As I could easily reach them, it occurred 

 to me to attempt to light paper by means of them ; but for some time I did not succeed in 



