I. BATHING, NARRAGANSETT PIER, R. I. Many people spend their summers at the seashore. Many large cities are on and near fine beaches. On hot days and evenings, crowds of city people with children go to the beach to get cool. Do you know of any beach? If you do, tell about it. Do you know of any people who go to the seashore for the summer? TIDES.-Another movement of the water of the ocean is called the TIDE. For a little more than six hours the water slowly rises on the beach, when it reaches HIGH TIDE. Then for another six hours it slowly falls to LOW TIDE. How many times does the of the tide? What effect has the high tide on the beach in the picture below? What effect has the low tide on the beach in the picture on the next page? Note the seaweed that has been washed in by the tide. Sea food, such as oysters, clams, escallops, and crabs, are more easily procured during low tide. HARBORS. The ocean has become the great thoroughfare for trade and travel. On its waters vessels, laden with merchandise and people from every country, pass to and fro. Under its waters the telegraphic cable extends which connects the great cities of the world. All vessels must anchor in some arm of the ocean, where they are protected from fierce winds and storms. In such havens they can easily discharge and take on passengers, supplies, and freight. Such an arm is a harbor. The best harbors have deep water and moderately HIGH TIDE, ENGLISH COAST. tide flow and ebb in twenty-four hours, high shores. The wide, deep mouths or a day? of rivers form fine harbors. Wooden How many of you have seen the flow and ebb and stone piers are constructed to enable the cargoes to be directly discharged upon the shore. In places where the water is shoal these piers ex tend out for a long distance into the water. On dangerous reefs to warn mariners at sea. Buoys are also used to point out the position of something dangerous beneath the water and to di Trace the warm currents in the illustration. rect the course of vessels in the channel. Lighthouses and light-ships are in charge Tell which shores of the continents are affected of special by them. COLD CURRENTS flow from the cold regions of the earth to the warm regions. LAND'S END, ENGLISH COAST. RIVERS OR CURRENTS IN THE OCEAN. more plants and animals to live in the water and on the land of the cold countries than otherwise could live there. The cold currents cool the heated land surface and warmer waters, making a more even temperature. Trace the cold currents. Tell what continental shores are affected by them. In this interchange of the hot and cold currents the life of the world has been strengthened. More animals, plants, and people can live in both the hot and cold sections. Bring in pic lines are constantly changing. All shore The changes in shore-lines are caused by the flow and ebb of the tide, by the waves, by the currents, and by the fact that all the rivers are carrying great quantities of mountain waste to the sea. Some sections of the coast are slowly rising, thus pushing the sea back from the land. Other sections of the coast are slowly sinking, thus allowing the water to flow in farther on the land. THE AIR. Through this interchange of gases the Air surrounds us on all sides, although air is kept pure for man and animals. we cannot see it. Mankind, animals, and plants depend upon it for the "breath of life." If there were no air, or atmosphere, surrounding every part of the earth, there could be no living thing upon it. Air is made up of several gases and vapor of water. We There is always a greater or less amount of VAPOR OF WATER in the air which is also needed by all living things. How does the moisture get into the air? The streets and all sur faces are said to "dry off" after a rain, but the moisture has not all soaked into the ground. It has simply disappeared. It has been absorbed into the air. It has been changed from water, which is easily seen, to vapor, which is unseen, by the process of evaporation. The mud-puddles will dry faster on a warm day than on a cool day. This is because warm air will hold more moisture than cold air. The puddles will dry faster on a windy day than on a still day. On which day will more air come in contact with the surface of the water? pend more upon these. The principal life-giving gas is OXYGEN. It is given to the air from all plant life. People and animals would suffocate if it were not for the oxygen which they breathe in, and which keeps their blood pure. Oxygen causes the burning of all substances. It also causes the rusting of iron and the decay of many substances. CARBONIC-ACID GAS 28 given to the air by all burning and decaying substances, and in the breath of all animals. It would poison all animal life and mankind if allowed to remain in the air. A wise means was provided by our Creator for taking this poison from the air. Carbonic-acid gas is needed by all plant life. All vegetation breathes it in. The plants could not live without it. up Water is evaporating all over the earth, giving to the air the needed moisture to support life. Water evaporates faster in the warm regions than in the cold regions, although snow is always evaporating. How does the water form to make rain? Breathe on a cold mirror or glass. It is misty, in a room of ordinary warmth. Can you think whence the tiny drops |