1 6 THE WORLD'S LUMBER ROOM. 



which is always present everywhere, and is revealed to us in 

 part, but only in part, whenever a sunbeam shines into the 

 room. 



" For the sun," says Daniel Culver well, " discovers 



Fig. 7. VEGETABLE DEBRIS FOUND IN SNOW. (Magnified 500 times.) 



atomes, though they be invisible by candle-light, and makes 

 them dance naked in his beams." 



And the electric beam does even more, for it shows us 

 that instruments which have been washed, and even polished, 

 and look spotlessly clean in ordinary light, are simply dirty 

 when seen by its searching light, if they have been left but 

 an instant exposed to the air. 



