And now we will go with Lula to the North River pier, where her great steamer lies, and see what she intends to carry to Liverpool.  Bales of cotton, barrels of flour, of beef, and of petroleum.  All very good, so good-by to her.  In a few weeks we will see what she brings back.

Come, Mary, what has Philadelphia for San Francisco?  Oh, what a load the “Sea-Gull” must take of machinery, steam-engines, tobacco, and oil; and such a quantity of other things, that the “Sea-Gull” will need to make many voyages before she can take them all.  We load her at this busy wharf, where the coal-vessels are passing in and out for New York and Boston, and the steamers are loading for Europe, and the little coasters crowding in one after another; and away we go for the voyage round the “Horn,” where the “Sea-Gull” will meet her namesakes, and perhaps some stormy winds besides.

Meantime Nina’s “Racer” has been stored full of cotton cloths and hardware, and has raced out of Boston Harbor so swiftly that fair winds will take her to Gibraltar in three weeks.

And so you have all engaged in the carrying trade; but as yet you have carried only one way.  To complete the game, we must wait for Lottie to bring the “Rosette” safely home with salt-petre and indigo and hides and ginger and seersuckers and gunny-cloth.  And the “North Star” must steam her quick way across the Atlantic, and return with salt and hardware, anchors, steel, woolens, and linens.  Mary must beat her way round Cape Horn, and home again with wool and gold and silver.  And the swift “Racer” must quickly bring the figs and prunes and raisins, and the oranges and lemons, that will spoil if they are too long on the way.

So children may play at the carrying trade, and so their fathers and uncles may work at it in earnest:  and so also hundreds of little workers are busy all the world over in another carrying trade, which keeps you and me alive from day to day; and yet we scarcely think; at all how it is going on, or stop to thank the hands that feed us.

England and Italy are kingdoms, and the United States a republic, and they all engage in this business, and are constantly sending goods one to another; but there are other kingdoms, not put down on any map, that are just as busy as they, and in the same sort of work too.

The earth is one kingdom, the water another, and there is the great republic of the gases surrounding us on every side; only we can’t see it, because its inhabitants have the fairy gift of being invisible to us.  Each of these kingdoms has products to export, and is all ready to trade with the others, if only some one will supply the means; just as the Frenchmen might stand on their shores, and hold out to us wines and prunes and silks and muslins, and we might stand on our shores, and hold out gold and silver to them, and yet could make no exchange, because there were no ships to carry the goods across.  “Ah,” you may say, “that is not at all the case here; for the earth, the air, and the water are all close to each other, and close to us, and there is no need of ships; we can exchange hand to hand.”