250 RIVERBY 



I amused myself by wading down into it as into 

 a fountain. The air above was muggy and hot, the 

 thermometer standing at about eighty-six degrees, 

 and this cooler air of the cave, which was at a 

 temperature of about fifty-two degrees, was sep- 

 arated in the little pool or lakelet which is formed 

 from the hotter air above it by a perfectly horizon- 

 tal line. As I stepped down into it I could feel it 

 close over my feet, then it was at my knees, then I 

 was immersed to my hips, then to my waist, then 

 I stood neck deep in it, my body almost chilled, 

 while my face and head were bathed by a sultry, 

 oppressive air. Where the two bodies of air came 

 into contact, a slight film of vapor was formed by 

 condensation; I waded in till I could look under 

 this as under a ceiling. It was as level and as well 

 defined as a sheet of ice on a pond. A few mo- 

 ments' immersion into this aerial fountain made one 

 turn to the warmer air again. At the depression in 

 the rim of the basin one had but to put his hand 

 down to feel the cold air flowing over like water. 

 Fifty yards below you could still wade into it as 

 into a creek, and at a hundred yards it was still 

 quickly perceptible, but broader and higher; it had 

 begun to lose some of its coldness, and to mingle 

 with the general air; all the plants growing on the 

 margin of the watercourse were in motion, as well 

 as the leaves on the low branches of the trees near 

 by. Gradually this cool current was dissipated and 

 lost in the warmth of the day. 



