Because steel will remain magnetized, but iron soon loses the magnetic properties. What is a compass? A _compass_ is an instrument containing a magnetic needle, so balanced as to move easily on a pivot. In what direction does this needle always point? This needle always points toward the north. By whom is the compass used? It is used by travellers to guide them on their journey; by surveyors to mark out the boundary lines between different properties; and by seamen to point out their way across the sea from one place to another. Before the Mariner’s Compass was invented, seamen were afraid to venture out of the sight of land, for fear of being lost on the ocean; for they then had no means of telling where they were, or in what direction to guide their vessels, so as to reach the land again. Electro-Magnetism. Are magnetism and electricity much alike? Yes; they are so nearly alike that many persons think they are identical. What is an electro-magnet? An _electro-magnet_ is a magnet obtained by means of electricity. Of what is the magnet made? The magnet is made of soft iron, around which are wound a great many coils of wire, and these are covered with silk. How is the soft iron made into a magnet? The iron is magnetized by the passage of electricity through the wire. Of what use is this magnet? It is used in the electro-magnetic telegraph. When and where was the first line of telegraph built? The first line of telegraph was built in 1844, from Washington to Baltimore, by Professor Morse. What is the principle of the telegraph? At one end of the telegraph wire is an electrical battery, and at the other end is an electro-magnet. When a message is to be sent, the electricity is transmitted through the wire to the soft iron of the electro-magnet, which causes the iron to move, and this motion is conveyed to the machinery, which is needed to print the message in letters or signals, so as to be understood. Does electricity move rapidly? Yes; its velocity is such as to move around the earth in a quarter of a second. What is the electrical battery called? The electrical battery is called a _key_. What is the electro-magnet called? The electro-magnet is called a _receiver_. For what are the key and receiver used? The key is used for sending messages, and the receiver for receiving them. What must each station have? Each station must have both a key and a receiver, so as to send as well as receive messages. What is the Atlantic cable? The Atlantic cable is a telegraphic wire reaching across the Atlantic Ocean, from America to Europe. When was the first Atlantic cable laid? The first Atlantic cable was successfully laid in 1866, between Newfoundland and Ireland. It is eighteen hundred and sixty-four miles long, and its success is chiefly due to Cyrus W. Field. Of what use is the Atlantic cable?