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Catechism of Familiar Things; Their History, and the Events Which Led to Their Discovery, A

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<SPAN name="CHAPTER_XXI" id="CHAPTER_XXI"></SPAN>CHAPTER XXI.</h2> <h3><span class="smcap">Electricity, Electric Currents, Electric Battery, Electrotyping, Stereotyping, Telegraph, Ocean Cable, Lightning Rod, The Gulf Stream, The Mt. Cenis Tunnel, The Suez Canal, Suspension Bridges, Eminent Americans.</span></h3> <p><b>What is the nature of Electricity?</b></p> <p>A form of energy into which all other forms can readily be converted.</p> <p><b>What is an Electric current?</b></p> <p>Electricity manifests itself in a variety of ways, but all may be arranged under two heads, <i>viz.</i>, 1, as a charge; 2, as a current. By means of friction, many bodies become electrified&mdash;that is, have acquired an electrical charge. If this charge is in great quantity we call it high tension. When a body containing an electrical charge is brought in contact with other bodies through which electricity is capable of passing, there ensues a current of electricity. Such bodies are called conductors.</p> <p><b>What are the sources of currents?</b></p> <p>There are currents produced by chemical action called voltaic currents; by the action of heat, or thermo-electric currents; by the motion of magnets, or magneto-electric currents.</p> <p class="center"><ANTIMG src="images/image_19.jpg" alt="REMOVING THE EARTH FROM THE CANAL BY MEANS OF DROMEDARIES." width="481" height="418" /><br /> <span class="caption">REMOVING THE EARTH FROM THE CANAL BY MEANS OF DROMEDARIES.</span></p> <p class="center"><ANTIMG src="images/image_20.jpg" alt="OPENING THE SUEZ CANAL&mdash;PROCESSION OF SHIPS." width="480" height="322" /><br /> <span class="caption">OPENING THE SUEZ CANAL&mdash;PROCESSION OF SHIPS.</span></p> <p><span class="pagenum"><SPAN name="Page_211" id="Page_211"></SPAN>[211]</span></p> <p><b>What is positive and what negative electricity?</b></p> <p>No difference in electricity in itself. When a body has more than its natural amount of electricity, it is said to be charged positively; when it has less than its natural amount it is negatively charged.</p> <p><b>What is a Cell; what a Battery?</b></p> <p>If a piece of zinc and copper joined by a wire be dipped in a liquid&mdash;generally weak sulphuric acid&mdash;which will act chemically on the metals, a current is produced. Such an arrangement is called a couple, or cell. If many cells are connected, then it is called a battery.</p> <p><b>What is Thermo-electricity?</b></p> <p>If two bars of any unlike metal&mdash;for example, antimony and bismuth&mdash;be soldered together at one end, and the other ends be connected by a wire and then the soldered end heated, a current will flow.</p> <p><b>What effects are produced by currents?</b></p> <p>They produce heat, light, decomposition and combination in liquid chemical compounds; they melt all metals, excite magnetism, and in the animal body excite movements of the muscles.</p> <p><b>Can you specify these effects?</b></p> <p>A strong battery produces heat in such a degree that all metals can be melted. Light is produced in flashes, or if the end of the leading wires are connected with two pencils of hard carbon, and brought very near together, then a brilliant light, or arc, called the voltaic arc, is produced. This is the dazzling bright light which we call electric light. The chemical effect of a current in decomposing compound substances is called electrolysis. In this way water can be decomposed into its compounds, hydrogen and oxygen; copper sulphate into sulphur and metallic copper, etc. In this way we can deposit strong adherent films of metal on the surface of any conductor; for if the article to be coated be attached to the negative electrode of a battery, and dipped into a solution of <span class="pagenum"><SPAN name="Page_212" id="Page_212"></SPAN>[212]</span>the metal with which we desire to coat the article, say copper or silver, and the positive electrode be attached to a plate of copper and also dipped into a liquid, when the current passes, the metal will be decomposed and deposited in a uniform layer over the article at the negative electrode. This process is called <i>electro-plating</i>.</p> <p><b>What is Electrotyping?</b></p> <p>It is the process of copying medals, type, wood-cuts, engraved copper and steel plates, etc., by means of electrical deposition. It is chiefly used for making, from the ordinary movable types, plates of fixed metallic types, for printing books.</p> <p><b>Describe the process.</b></p> <p>The article to be copied is first covered with black-lead, and then a mould is made of it in wax or gutta-percha. This mould is placed in a solution of sulphate of copper, and attached to the negative pole of the battery, while a plate of copper is hung from the positive pole. The electric current decomposes the copper, which is deposited in a thin film upon the mould. This film is removed and stiffened by being backed with metal.</p> <p><b>What is the difference between Electrotyping and Stereotyping?</b></p> <p>In stereotyping, a plaster of Paris mould is taken from the types, and upon this mould melted type-metal is poured, which, when hardened, makes a solid plate.</p> <p><b>Is there any other method of stereotyping?</b></p> <p>Yes; that known as the paper process. A uniform sheet of soft matter is formed by pasting together sheets of thin, tough tissue paper. The types are oiled, and the soft, moist sheet is placed on them and beaten down with a stiff brush until it receives an impression of the type-form. Both are then run through a press, and on being taken out the paper is found to form a perfect mould. Into this mould the type-metal is poured and the plate formed.</p><p><span class="pagenum"><SPAN name="Page_213" id="Page_213"></SPAN>[213]</span></p> <p><b>Can you tell me some magnetic effects of the current?</b></p> <p>All conductors become magnetic during the passage of a current through them, and thereby acquire all the properties of a magnet. There are bodies which are natural magnets, and they are called permanent magnets. Those which become magnets only during the passage of a current are called electro-magnets.</p> <p><b>Do you know any application of those magnets?</b></p> <p>They are employed in a great variety of electrical apparatus, principally in telegraphy.</p> <p><b>When was the first telegraph established?</b></p> <p>It was made in 1836, being invented by Prof. Steinheil, of Munich, and adopted by the government of Bavaria. It was 12 miles long, and the signals were made by small bells.</p> <p><b>Who was the inventor of the telegraph in this country?</b></p> <p>Samuel F.B. Morse, who was born at Charlestown, Mass., April 27, 1791. He began life as a painter, but did not give his whole attention to art&mdash;chemistry and experiments in electricity and galvanism claiming much of his time. He first conceived the idea of the telegraph in 1832, and exhibited his invention to Congress in 1837. He struggled on with scanty means, and was about to give up in despair when Congress appropriated $30,000 for an experimental line, which was opened on May 12, 1844, between Washington and Baltimore. Prof. Morse died in 1872, but not before he had reaped honors and fortune from his invention.</p> <p><b>How rapidly does the electric current travel through the wires?</b></p> <p>From experiments made it appears to be about 15,400 miles in a second.</p> <p><b>Can more than one message be sent at the same time on the same wire?</b></p> <p>Yes; it is possible now to send several messages at the same time.</p><p><span class="pagenum"><SPAN name="Page_214" id="Page_214"></SPAN>[214]</span></p> <p><b>What is a Cable?</b></p> <p>It is a telegraph wire under water. Prof. Morse, in 1842, laid a wire insulated by a covering of hemp coated with pitch-tar and India-rubber between Governor's Island and the Battery, New York. Several attempts were made in other countries.</p> <p><b>What was the greatest telegraphic undertaking?</b></p> <p>That of connecting Europe with America by a submarine cable spanning the ocean, which was commenced in 1857 and completed August 5, 1858.</p> <p><b>To whom do we owe this grand undertaking?</b></p> <p>This honor is entirely due to Mr. Cyrus W. Field. Mr. Field was born at Stockbridge, Mass., on November 30th, 1819. In 1853 he became interested in ocean telegraphy, and after many reverses succeeded in laying the first cable in August, 1858. The message sent by Queen Victoria to the President of the United States, consisting of 99 words, occupied 67 minutes in transmitting. In September of the same year this cable ceased to work, but the energy of Field restored confidence, and another cable was made and laid down in July, 1865, but after 1200 miles were deposited it was lost. In 1866 another was made and successfully laid in July. In August the lost cable was found and spliced, and carried to the western shore.</p> <p><b>What is a Dynamo-electric machine?</b></p> <p>A machine by which very powerful currents can be obtained directly from mechanical power. In these, by means of a steam-engine or other power, a number of coils of wire called the armature are set into rapid revolution between the poles of powerful electro-magnets. All currents are caused to flow from the armature in one direction by means of a contrivance called the commutator. Very successful machines of this sort are the Gramme machine, the Siemens, and, principally, the so-called Brush machine. By these the electric light is now generally produced.</p><p><span class="pagenum"><SPAN name="Page_215" id="Page_215"></SPAN>[215]</span></p> <p><b>What is a Lightning Rod?</b></p> <p>It is a rod of iron placed against a building to protect it from lightning. Three or four feet of one end is in the moist ground or in water, while several feet of the other end extend above the highest part of the building. The upper end of the rod is pointed with copper or some other metal which will not easily corrode.</p> <p><b>By whom was it invented?</b></p> <p>By Benjamin Franklin, and first announced by him in his "Poor Richard's Almanac" for 1753. Franklin was born at Boston, Mass., in 1706. By his talents, prudence, and honesty he rose from humble beginnings to be one of the foremost men of his time. He was one of the committee of five chosen by Congress to prepare the "Declaration of Independence" which he with other patriots afterwards signed. Towards the close of the year 1776 he was sent as ambassador to the French Court, and remained in Europe some time. He returned home in 1785, and died at Philadelphia on the 17th of April, 1790.</p> <p><b>What is the Gulf Stream?</b></p> <p>It is a warm current in the Atlantic Ocean.</p> <p><b>What is its origin?</b></p> <p>It may be considered as beginning on the west coast of Africa, within the region of the trade winds. These cause a westward flow, known as the equatorial current. On reaching the coast of Brazil, the greater portion of this current bends northward, carrying with it the waters of the Amazon and Orinoco, and passes through the Caribbean Sea into the Gulf of Mexico. Here it is further heated, and rushes out through the only outlet, the Straits of Florida.</p> <p><b>Describe its course.</b></p> <p>Deep and narrow, it runs by Florida with a velocity varying from two to five miles an hour, and pressed by the cold current between it and the shore, flows parallel to the coast <span class="pagenum"><SPAN name="Page_216" id="Page_216"></SPAN>[216]</span>as far as Cape Hatteras. Meeting shoals near this point, the banks of sand extending as far as Newfoundland, it there turns abruptly to the east, and with diminished speed and increased width, rolls onward towards the coast of Europe. Before long it divides into two great branches&mdash;the northern and southern. The former extends as far as Spitzbergen; the latter, sweeping along by the Madeira and Canary Islands, returns to the equator, completing the circuit.</p> <p><b>What influence has the Gulf Stream on the climate of Europe?</b></p> <p>Various opinions have been expressed as to this. It has been estimated that the amount of heat arising from the stream on a winter's day, is sufficient to raise the atmosphere over the British Isles from the freezing point to a summer temperature.</p> <p><b>How may the Gulf Stream be distinguished?</b></p> <p>It can be distinctly traced in the ocean by its dark indigo color, its temperature, and the swiftness of its waters.</p> <p><b>Which is the largest tunnel in the world?</b></p> <p>The Mt. Cenis Tunnel, or the tunnel of Col de Frejus, by both of which names it is known. It is the longest subterranean route for commerce and travel yet constructed, being 7-1/4 miles in length. It is on the crest of the Cottian Alps, about 16 miles south-west of the summit of Mt. Cenis Pass. It was begun in 1857, and finished in 1871.</p> <div class="blockquot"><p><i>Col</i>, a defile.</p></div> <p><b>What other great engineering work can you mention?</b></p> <p>The Suez Canal, a ship canal running across the Isthmus of Suez, and connecting the Mediterranean with the Red Sea. The canal is 100 miles in length, and through it an uninterrupted communication is established whereby large sailing vessels and steamers may pass from sea to sea, and thus <span class="pagenum"><SPAN name="Page_217" id="Page_217"></SPAN>[217]</span>avoid the long and dangerous voyage around the Cape of Good Hope.</p> <p><b>To whom is the world indebted for this canal?</b></p> <p>This great work owes its inception and completion to the enterprise and indomitable energy of Ferdinand de Lesseps, who was born at Versailles, France, on the 19th November, 1805. In January, 1856, he obtained a charter from the Egyptian Government for a company to construct the canal, and began work in 1859. Though beset by many difficulties, the persistent energy of De Lesseps fought its way to success, and in 1869 he had the satisfaction of seeing the waters of the Mediterranean and the Red Sea mingle in the Bitter Lakes. He has since been engaged in many engineering projects, the latest being a canal across the Isthmus of Panama to connect the Atlantic and Pacific oceans.</p> <div class="blockquot"><p><i>Inception</i>, beginning.</p> <p><i>Indomitable</i>, not to be subdued.</p> <p><i>Persistent</i>, inclined to hold firm.</p></div> <p><b>What is a Suspension Bridge?</b></p> <p>A bridge supported by wires, ropes, or chains, which usually pass over high piers or columns at each end, and are secured in the ground below.</p> <p><b>Name some of the largest bridges of this kind.</b></p> <p>That at Niagara, those over the Allegheny at Pittsburg and the Ohio at Cincinnati, and the great East River bridge, which connects New York and Brooklyn.</p> <p><b>Who planned these bridges?</b></p> <p>John A. Roebling, who was born at Mulhausen, Prussia, June 12, 1806. In 1831 he emigrated to this country, and to his genius we are indebted for the bridges above named. The reports, plans, and specifications of the East River bridge were completed, and the work begun, when Roebling was severely injured in the foot while directing his work. Lockjaw succeeding amputation, he died in Brooklyn, July 22, 1869.</p><p><span class="pagenum"><SPAN name="Page_218" id="Page_218"></SPAN>[218]</span></p> <p><b>To what great Civil Engineer has the West given birth?</b></p> <p>James B. Eads. Born at Lawrenceburg, Indiana, May 28, 1820, he began life as a clerk on a Mississippi river steam-boat. In 1842 he entered a firm engaged in recovering sunken property, and with such success that he retired with a fortune in 1857. During the civil war he devised a plan for the defence of the Western waters, and constructed several iron gun-boats with many novel features of his own invention. He has since acquired reputation as projecting and constructing engineer of the Illinois and St. Louis bridge, and by building jetties at the South Pass of the Mississippi, by which the depth of the river is increased, and it is made more navigable. These jetties are projecting dikes of brush, fascines, and stone.</p> <div class="blockquot"><p><i>Fascines</i>, bundles of rods or of small sticks of wood, bound at both ends and at intermediate points, used in filling ditches, etc.</p></div> <p><b>Give the names of some distinguished American inventors.</b></p> <p>Eli Whitney, the inventor of the Cotton Gin, born in Westborough, Mass., 1765; died 1825. Jethro Wood, the inventor of the modern cast-iron plow, born at White Creek, N.Y., 1774; died 1834. Cyrus H. McCormick, inventor of the mowing machine, born at Walnut Grove, Virginia, in 1809.</p> <p><b>Who was the inventor of the Sewing Machine?</b></p> <p>Elias Howe. He was born at Spencer, Mass., July 9, 1819. When a boy he worked in a cotton mill at Lowell, but afterwards entered a machine shop in Boston. Here he conceived the idea of the sewing machine, and after long days of labor, part of which time he and his family lived on the kindness of a friend, he completed his invention. After many struggles, his talent, industry, and perseverance were rewarded, and long before his death, which occurred in October, 1867, he had acquired a large fortune.</p><p><span class="pagenum"><SPAN name="Page_219" id="Page_219"></SPAN>[219]</span></p> <hr style="width: 65%;" /><h2>
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