“It’s ugly stuff to pitch,” said Moke, twisting the root in the tines of his fork to assist his brother. “It’s strange that it always lands against the wind!” said Poke. “I don’t see that it’s strange at all,” replied Perce. “The only things that the wind from the sea blows ashore are things afloat on the surface, like driftwood. It blows the surface water too, but that is all the time running back; and it carries with it things below the surface.” “Of course! I know all about that!” said Poke. “The under-tow,” suggested Moke. “Well! it’s the under-tow that lands the kelp,” returned Perce. “It works both ways. When the wind blows off shore it blows the surface water back; and that brings up the under-current with the seaweed. That’s the way it is on our beaches.” Moke and Poke knew the facts well enough; but Perce, who prided himself on being a rather intelligent boy, liked to explain things. He went on: “There’s another thing you’ve noticed: how much warmer the water is sometimes when there’s a sea-breeze, than when it blows off the land; just the contrary of what you would expect.” “I guess every fellow who goes in swimming much——” Moke began. “Has noticed that,” Poke ended. “It’s because the sea-breeze is cooler than the land-breeze,” said Moke. “And that makes the water seem warm to you,” said Poke. “There’s something besides that,” Perce replied. “It’s the surface water that is warmest; and the sea-breeze keeps that rolling on the beach. I’m speaking of sunny days; in cloudy weather there isn’t much difference. The sun warms the sand, and the sand warms the water. But a land-breeze blows it off, and brings up the cold under-current. Think of that the next time you go in swimming, and see if it isn’t so.” The twins thought it strange he should know so much, as he had no Uncle Moses; he didn’t tell them he had got his lore from his father, who was one of the most intelligent farmers on the coast. “I shouldn’t like to go in swimming here now!” said Poke, turning to look at the waves, still dark with rolling seaweed and sand. “It’s wonderful,” said Perce, “how pure the ocean keeps, with all the dirt and things forever washing into it,—though it isn’t always so pure as it looks. Don’t you know that fishermen have to take up their gill-nets and dry ’em about every four days?” “That’s to keep ’em from rotting,” said the twins. “But what makes them rot?” returned Perce. “It isn’t the water; it’s what’s _in_ the water.” “The slime,” said Moke. “They come up all covered with slime,” said Poke. “That slime,” Perce replied, “is all a kind of life. Drying kills it. But if the nets are left long in the water, it grows, and takes the life out of ’em; that’s what you call rotting. In a few days you can see fine green grass growing all over the twine. Then, how quick the bottom of a boat, or a rope left in the water, or a sunken anchor, gets coated with barnacles! The clearest sea water is swarming alive with things you can’t see!”