How To Make a Hot Air Balloon

McGuffey's Fifth Eclectic Reader Revised Edition Lesson 73: The Examination.

"Oh! I see now as plain as day; the cold air settles down all round, like the iron box, and drives up the hot air as fast as the fire heats it, in the middle, like the water; and so the hot air carries the smoke along up with it, just as feathers and things in a whirlwind."

This lesson in the McGuffey's Fifth Eclectic Reader Revised Edition, discusses about how the heated air rises, and why so.  It is because the hot air has molecules move at a quicker rate, which makes it lighter then cold air, which is denser making it heavier.

This image is from the book "Moonlight above the clouds".   It shows the balloon  almost crashing into the train*