90 PHOSPHORESCENCE IN 
bottom and on the walls of dark damp mines or 
moist caverns, on old decayed humid towers, etc.» 
evolve a tranquil phosphoric light, which some - 
times attracts attention by its intensity. 
Fig. 10. 
The phosphorescence of f. subterranea is fre- 
quent in coal mines, and has been many times 
observed near Dresden. Counsellor Ehrman has 
spoken with enthusiasm of its pleasing effect in 
these lone and desolate places. Having once de- 
scended into one of the Swedish mines, he saw 
these “vegetable glowworms”’ gleaming along its 
walls or shining in some obscure recess. 
Caverns in the granitic rocks of Bohemia are 
often beautifully decked with this luminous cryp- 
togam, and I am told that our Enghsh coal-mines 
occasionally exhibit, by its aid, a light sufficiently 
clear to admit of reading ordinary print. 
