16.  “Why,—­I guess,” replied the boy, hesitating, “I guess,—­I guess I don’t know.”

“Did you ever get up in a chair to look on some high shelf, so that your head was brought near the ceiling of a heated room, in winter? and did you notice any difference between the air up there and the air near the floor?”

17.  “Yes, I remember I have, and found the air up there as warm as mustard; and when I got down, and bent my head near the floor to pick up something, I found it as cold as could be.”

“That is ever the case; but I wish you to tell me how the cold air always happens to settle down to the lower part of the room, while the warm air, somehow, at the same time, gets above.”

18.  “Why, why, heavy things settle down, and the cold air—­yes, yes, that’s it, I am sure—­the cold air is heavier, and so settles down, and crowds up the warm air.”

“Very good.  You then understand that cold air is heavier than the heated air, as that iron is heavier than the water; so now we will go back to the main question—­what makes the smoke go upwards?”

19.  “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.  Well!  I have found out what makes smoke go up—­is n’t it curious?”

20.  “Done like a philosopher!” cried Bunker.  “The thing is settled.  I will grant that you are a teacher among a thousand.  You can not only think yourself, but can teach others to think; so you may call the position yours as quick as you please.”

Definitions.—­2.  In-tel-lec’tu-al, treating of the mind. 3.  Tem’-pered, brought to a proper degree of hardness. 4.  Com-pact’, closely and firmly united, solid, dense. 4.  Por’ous, full of pores or minute openings. 6.  E-vap’o-rat-ed, passed off in vapor. 7.  In-gen’ious (pro. in-jen’yus), well formed, skillful. 7.  Phe-nom’e-non, whatever is presented to the eye. 8.  In’ter-vals, spaces of time. 12.  Ap-pa-ra’tus, utensils for performing experiments.

Note.—­Locke Amsden is represented as a bright young student in search of a position as teacher of a district school in Vermont.  Mr. Buuker, the “Examining Committee,” is a queer, shrewd old farmer, who can neither read nor write, but by careful observation has picked up a large amount of valuable information.  The story opens in the midst of the examination.

LXXIV.  THE ISLE OF LONG AGO.

Benjamin Franklin Taylor (b. 1819, d. 1887) was born at Lowville, N.Y.  He graduated at Madison University, of which his father was president.  In 1845 he published “Attractions of Language.”  For many years he was literary editor of the “Chicago Journal.”  Mr. Taylor wrote considerably for the magazines, was the author of many well-known favorite pieces both in prose and verse, and achieved success as a lecturer.