AND COLD ON WATER. 115
suppose the mist which we noticed was produced in the same manner as steam is; only that it is the sun's heat which turns the particles of water into vapour. But, papa, what becomes of it all then ? for if this watery vapour is lighter than the air, it would continue to rise till it had quite disappeared."
" When the string of your kite broke, Lewis, and it soared far away, for a short time, higher than it had ever been before, what do you suppose occasioned it to fall again ?"
Lewis thought for a moment, and then said, " Partly because I had no string to guide it, and partly, I suppose, papa, because the air above might be lighter, and not able to support its weight."