The Wonder Book of Knowledge The Marvels of Modern Industry and Invention the Interesting Stories of Common Things the Mysterious Processes of Nature Simply Explained

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Title: The Wonder Book of Knowledge

       The Marvels of Modern Industry and Invention the Interesting

              Stories of Common Things the Mysterious Processes of Nature

              Simply Explained

Author: Various

Editor: Henry Chase Hill

Release Date: October 19, 2012 [EBook #41111]

Language: English

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HOW COLOR PRINTING IS DONE

A plate is made for each of the three printing colors, yellow, red and blue, as explained on page 382. First, yellow is printed, then red on the yellow, and last, blue on the yellow and red combination. Combinations of these three colors in various proportions produce all the other tints which appear in the original subject. Above are shown the separate plates and also the combined result of all three. Extreme care is necessary to make all the plates register exactly together.

THE WONDER BOOK

OF KNOWLEDGE

THE MARVELS OF MODERN INDUSTRY AND INVENTION

THE INTERESTING STORIES OF COMMON THINGS

THE MYSTERIOUS PROCESSES OF NATURE

SIMPLY EXPLAINED

COMPILED AND EDITED

BY

HENRY CHASE HILL

WITH THE CO-OPERATION OF EXPERTS

REPRESENTING EACH INDUSTRY

Illustrated with

780 Photographs and Drawings

PHILADELPHIA

THE JOHN C. WINSTON COMPANY

PUBLISHERS

Copyright

, 1921

By L. T. MYERS

Copyright

, 1917-19

Preface

This book is presented to those, both young and old, who wish to have a non-technical account of the history, evolution and production of some of the every-day wonders of the modern industrial age; coupled with occasional glimpses of the wonderful object-lessons afforded by nature in her constructive activities in the animal, vegetable and mineral kingdoms; and simple, understandable answers to the myriad puzzling questions arising daily in the minds of those for whom the fascination of the Why and How is always engrossing.

Although not intended primarily as a child’s book, the interest-compelling pictures and clear, illuminating answers to the constant avalanche of questions suggested by the growing mind, unite in making far happier children in the home and brighter children at school. Parents and teachers will also recognize the opportunity to watch for subjects by which the child’s interest appears to be more than ordinarily attracted, and, in so doing, will be enabled to guide the newly-formed tendencies into the proper channels. With the greatest thinkers of the age advocating vocational training, and leading educators everywhere pointing out that the foundation of a practical education for life must be laid in the home, thoughtful parents will not overlook the fact that a book which both entertains and instructs is of supreme importance in the equipment of their children.

In the preparation of this book its function has been considered as that of gathering up some of the multitudinous bits of information of interest, both to the inquiring child and the older reader, and putting them in shape to be digested by the ordinary searcher after knowledge. The book is intended, not for a few technical specialists, but for the larger number of men, women and children who are not interested in exhaustive treatises, but who are seeking to gain some fair idea about the numberless every-day subjects that arise in ordinary conversation, or that they meet with in reading and about which they desire some definite and satisfactory information.

Most of us realize that we live in a world of wonders and we recognize progress in industries with which we come in personal contact, but the daily routine of our lives is ordinarily so restricted by circumstances that many of us fail to follow works which do not come within our own experience or see beyond the horizon of our own specific paths.

The workman who tends the vulcanizer in the rubber factory has come to take his work as a matter of course; the man who assembles a watch, or a camera, is not apt to appreciate the fact that there have been marvelous developments in his line of manufacturing; the operator of a shoe machine, or of an elevator, does not see anything startling or absorbing in the work—and so we find it almost throughout the entire list of industries.

The tendency of the seemingly almost imperceptible movement marking onward development in the work that is familiar is to dull the mind toward opportunities for improvement in the accustomed task. With the exception of the man who is at times impressed with the remarkable advances made in some strikingly spectacular industry, because such knowledge comes to him suddenly, the average workman is often too much inclined to regard himself as a machine, and performs his duties more or less automatically, without attempting to exercise imagination or those powers of adaptation upon which all progress has been builded.

A single volume is of necessity too limited a space for anything approximating a complete record of the vast progress which has been made in American Industry. Consequently it has only been possible to select the more characteristic features of the twentieth century and point out the strides by which some of the prominent industries have advanced to their present proportions. If the hitherto undisputed maxim that the more the individual knows the more he is worth to himself and his associates still prevails, the chronicling of the developments in some fields should stimulate thought and experiment toward the adaptation of similar methods in others. It is to that end that authorities in each of the industries presented have co-operated in the compilation of this interesting and instructive volume.

The Editor.

Table of Contents

The Story of the Submarine

[1]

Origin of Submarine Navigation.

The history of invention has no chapter more interesting than that of sailing under the ocean’s waves. The navigation of the air approaches it in character, but does not present the vital problems of undersea travel. Both these new fields of navigation have been notably developed within recent years, largely as a result of the great European war. It is the story of sailing in the depths beneath the ocean’s surface with which we here propose to deal. The problem was settled easily enough for his purpose by Jules Verne, in his Twenty Thousand Leagues Under the Sea. But that was pure fiction without scientific value. It is with fact, not fiction, that we are here concerned.

A Submarine About to Submerge

The story takes us back three hundred years, to the reign of James I, of England, when a crude submarine boat was built, to be moved by oars, but one of no value other than as a curiosity. At a later date a man named Day built a similar boat, wagering that he would go down one hundred yards and remain there twenty-four hours. So far as is known, he still remains there, winning the wager which he has not come up to claim.

Other such boats were constructed at intervals, but the first undersea boat of any historical importance was the American Turtle, built by a Yankee named David Bushnell during the time that the British held New York in the Revolutionary War. He sought to blow up the British frigate Eagle with the aid of a torpedo and nearly succeeded in doing so, seriously scaring the British shippers by the explosion of his torpedo.

The next to become active in this line of discovery was Robert Fulton, the inventor of the first practical steamboat. He, like Bushnell, was an American, but his early experiments were in France, where Napoleon patronized him. With his boat, the Nautilus, he made numerous descents, going down twenty-five feet in the harbor of Brest and remaining there an hour. He said that he could build a submarine that could swim under the water and destroy any war vessel afloat. But the French Admiralty refused to sustain him, one old admiral saying, Thank God, France still fights her battles on the surface, not beneath it.

Fulton finally went to England and there built a boat with which he attached a torpedo to a condemned brig, set aside for that purpose. The brig was blown up in the presence of an immense throng, and Fulton finally sold his invention to the British government for $75,000. Nothing further came of it.

The submarine next came into practical view during the American Civil War, when the Confederate government built several such vessels, known usually as Davids from their inventor. Now, for the first time, did such a craft demonstrate its powers. On the night of February 17, 1864, one of the Davids, the Hunley, blew up the steamship Housatonic in Charleston harbor. The wave caused by the explosion swamped the submarine and it and its crew found a watery grave.

Other submarines were built and experimented with, not only in the United States but in European countries. One of the later inventors was an Irish-American named John P. Holland, who, in 1876, built a submarine called the Fenian Ram. The Ram collapsed with the collapse of the Fenian movement. Other boats were built and tried, but the successful period of the submarine was deferred until after 1893, when the United States Congress appropriated $200,000 to encourage such an enterprise and invited inventors to submit designs. This, and a similar movement in France, formed the first official recognition of the value of vessels of this class.

The prize offered by Congress brought out three designs, one by Mr. Holland, the Ram inventor, one by George C. Barker, and a third by Simon Lake. The names of Holland and Lake have since been closely associated with the history of the submarine. Mr. Holland’s device secured approval and in 1894 he received a contract to build a submarine vessel. This, named the Plunger, was begun in 1895, but was finally abandoned and a vessel of different type, the Holland, was built in its place. It was accepted by the government in 1900. A number of others similar to the Holland were subsequently built.

The American Types.

The type of these vessels was what became known as the diving. They were controlled by a rudder placed at the stern of the vessel and acting in both a horizontal and a vertical direction, the force of the screw propeller driving the boat forward in the direction desired. In 1904 the navy of the United States possessed eight Holland boats and there were also a number of them in the British navy.

Mr. Lake’s design, offered in 1893 but not accepted, had as its novel feature a plan by which a door could be opened in the bottom of the ship and the crew leave and enter it in diving suits, the water being kept out by the force of compressed air. To maintain the vessel on an even keel he introduced four vanes, called hydroplanes, for regulating the depth of descent. By aid of these and the horizontal rudder it was found that the vessel would run for hours at a constant depth and on a level keel. There were other devices for diving or rising to the surface.

In 1901 Mr. Lake built a large vessel of this type which was sold to the Russian government and was in commission at Vladivostock during the Russian-Japanese War. He afterwards received orders from this and other governments for a number of vessels of the even-keel type, and his principles of control have since been generally adopted as the safest and most reliable controlling agency for under-water craft.

We have not in the above brief statement described all the efforts to invent a satisfactory under-water boat. In several of the nations of Europe experiments, more or less available, had been tried, but the most practical results were achieved by the American inventors, Bushnell, Fulton, Davy, Holland and Lake. It will suffice here to say that the most successful of submarines were those constructed by Holland and Lake. An important addition was made in 1901 in a French boat, the Morse, built at Cherbourg. The difficulty of navigators telling where they were when under water, and of changing their course safely without coming to the surface to reconnoitre, was in a large measure overcome by the addition of a periscope. This, rising above the water, and provided with reflecting lenses, enabled the steersman to discover the surface conditions and see any near vessel or other object. The Morse was able to sink in seventy seconds and her crew could remain under water for sixteen hours without strain.

A Mine-planting Submarine Designed in Berlin by Simon Lake in 1895 for the Russian Government

Twentieth Century Submarines.

We have given an epitome of the development of the submarine vessel up to the opening of the twentieth century. It had now reached a successful status of achievement and during the early years of that century was to display a remarkable progress. Holland and Lake may be looked upon as the parents of the modern development of the submersible boat, their designs being at the base of the great European progress.

France took up the work actively, its most successful early vessel being the Narval, built in 1899. This was 118 feet long by 8 feet 3 inches beam, 106 tons surface and 168 submerged displacement. She was a double-deck vessel controlled by Lake hydroplanes, and had installed steam power for surface travel and electric power for undersea work. The French at this time kept their methods secret, and no useful type had been developed in England, the result being that a plant was provided for the building of Holland boats in that country. Germany used the Lake devices, which had not been patented in that country and were made use of by the Krupps. Thus it appears that the modern submarines, as now built and used in the navies of the world, owe their success to principles of construction and devices for control originated and developed by American inventors.

Engine Power.

The internal-combustion engine is the heart of the submarine. Steam, with its heavy engine, has been long set aside, and electricity, derived from the storage battery, yet awaits sufficient development. Gasoline succeeded them. The internal-combustion engine became essential from its light weight and the fact that it could be started and shut down instantly. This is of prime importance, as permitting quick submergence or emergence, either to escape from a high-speed destroyer or to capture a merchantman. It weighs less per horse power, takes up less room and requires less fuel per hour than any other reliable motor. It was early used in both the Holland and Lake boats and is still the chief prime motor.

A Protector Fitted for Experimental Work Under Ice

The difficulty with the early boats was that they were slow in speed, making only from eight to nine knots per hour. Increased speed was demanded by governments and more powerful engines, within a fixed limit of weight, were demanded. In doing this engines were built of such flimsy construction that they soon went to pieces. The gasoline used also gave off a gas of highly explosive character and one very likely to escape from leaky tanks or joints. Several explosions took place in consequence, in one of which twenty-three men were killed. As a result all the nations demanded that a non-explosive fuel should be used, and builders turned to the Diesel engine as offering a solution to the difficulty.

This heavy oil engine, weighing about five hundred pounds per horse-power, was not adapted to the submarine, and efforts have been made to decrease the weight. These have not as yet had a satisfactory result and experiments are still going on.

The Periscope.

As the engine is the heart of the submarine, the periscope is its eye. This is, in its simpler forms, a stiff, detachable tube from fifteen to twenty feet long and about four inches in diameter. On its top is an object glass which takes in all objects within its range and transmits an image of them through a right-angled prism and down the tube. By means of other lenses and prisms an image of the external object is thus made visible to those within the submarine. In this process of transmission there is a certain loss of light, and to allow for that the image is magnified to about one-quarter above natural size.

A Submarine Under Ice

To obtain in this manner a correct idea of the distance of the object seen proved difficult, but by continued experiment this difficulty has been overcome. Mr. Lake developed an instrument suited to this purpose and one which gave a simultaneous view of the entire horizon. There is one fault in the periscope not easy to obviate. It is an instrument for day use only. When dark comes on it becomes useless, and this does away with the possibility of a successful submarine attack by night.

The periscope is the one part of the submarine scout equipment that is open to vision from the surface. But while the outlook of the undersea captain, aided by his telescopic sights, has a radius of several miles, the periscope tube, of only four or five-inch diameter and painted of a neutral tint, is not easily seen. If the sea is a little choppy it is difficult to discover it with the naked eye at about 300 or 400 yards away, or in a smooth sea at over 500 yards.

The idea that a submarine may be located by an aeroplane is looked upon by Mr. Lake as a fallacy, except in water of crystal-like clearness, like that of the Mediterranean or the Caribbean, and periscopes are now being made to scour the heavens as well as the horizon, so that the presence of an enemy aeroplane can easily be seen. An attack by an aeroplane bomb, therefore, can readily be avoided, in view of the difficulty of hitting such an object from the upper air.

The submarine is the guerrilla of the sea. Its tactics are like those of the Indian who fights under cover or lies in ambush for his enemy. It is the weaker party and can hope for success only through strategy. The old adage that all is fair in love and war applies to this new weapon of destruction as to every warlike instrument. It is its invisibility that makes the submarine the terror of the seas. This has been well proved during the European war. The North Sea and the English Channel have been invaded by German submarines which have made great havoc among merchant ships. And it is well to draw attention to the fact that submarines are safe from each other. In no case has a battle taken place between two of these armed sharks except in the one instance reported of an Austrian sinking an Italian submarine. But in this case the Italian boat was on the surface and was at the time practically a surface ship.

During the war the Germans were especially active in the use of the submarine, and did much in making them an effective terror of the seas. With no mercantile marine of their own to guard, they had a free field for attack in the abundant shipping of their foes. The loss of ships was so numerous and became such a common occurrence that little attention was finally paid to them except when great loss of life took place, as in the signal instance of the Lusitania.

Type of High Speed Ocean-going Submarine

The Voyage of the Deutschland.

The great mission of the submarine during the European war was as a commerce destroyer. Many ships were sunk and many lives, with cargoes of great value, were lost, and it was not until the summer of 1916 that the submarine appeared in a new rôle, that of a commerce carrier. On July 9th of that year the people of Baltimore were astounded by the appearance in their port of a submarine vessel of unusual size and novel errand. Instead of being a destroyer of merchandise, this new craft was an unarmed carrier of merchandise. It had crossed the Atlantic on a voyage of 4,000 miles in extent, laden with dyestuffs to supply the needs of American weavers.

This new type of vessel, the Deutschland, was an undersea craft of 315 feet length and a gross tonnage of 701 tons, its cargo capacity being more than 1,000 tons. It had crossed the ocean in defiance of the wide cordon of enemy warships which swarmed over part of its route, and reached port in safety after a memorable voyage, to the surprise and interest of the world. Leaving the port of Bremenhaven on June 18th, and halting at Heligoland for four days to train its crew, it made its way across the Atlantic in sixteen days. During this voyage it lay for two hours on the ocean bottom in the English Channel and was submerged in all not over ninety hours, the remainder of the voyage being made on the surface.

Its crew, composed of twenty-six men and three officers, found their novel voyage rather agreeable than otherwise. Supplied with plenty of good food, a well-selected library, a graphophone with an abundance of music records, and other means of convenience and enjoyment, their voyage was more of a holiday then a hardship, and they reached their transatlantic port none the worse for their hazardous trip. It was not the longest that had been made. Other submarines had voyaged from German ports to the eastern limit of the Mediterranean, but it was the most notable and attracted the widest attention.

The German Merchant Submarine Deutschland which Crossed the Atlantic in 1916, after Eluding the British Blockade

Courtesy of Baltimore American and C. & P. Telephone Co.

The return voyage promised to be more perilous then the outgoing one. A fleet of British and French ships gathered around the outlet of Chesapeake Bay, alert to capture the daring mariners and their ship, if possible. Ready to leave Baltimore on July 20th, with a return cargo of gold, nickel and rubber, the captain of the Deutschland shrewdly awaited a favorable opportunity and on August 1st began his voyage, plunging under sea as he left the American coast-line and easily evading the line of floating foemen. The return to its home port a success, a second round-trip voyage was made and completed on December 11th, in the course of which a convoying tug-boat was rammed and sunk with the loss of several lives, shortly after leaving New London, Conn. The Deutschland was sent out by private parties, for purely commercial purposes, not as a military enterprise.

Such is the story of a pioneer enterprise, that of the use of submarine vessels as commerce carriers. It is one not likely to be supplemented in times of peace, since surface boats would be cheaper and more available. But in future wars—if such there are to be—it may point to a future of advantageous trade.

Submarine Dredging.

Commerce is not the only peaceful mission of the submarine. In 1895 was organized an association known as the Lake Submarine Company, its purpose being to use the Lake type of submarine boat for the recovery of lost treasures from the sea bottom and for other possibilities of undersea work. This company is still in existence, its various purposes being to recover sunken ships and their cargoes, to build breakwaters and other submerged constructions, to aid in submarine tunnel building, to dredge for gold, to fish for pearls and sponges, and for similar operations.

The first vessel adapted to these purposes was the Argonaut, built by Simon Lake in 1894. The important feature of this boat was a diver’s compartment, enabling divers to leave the vessel when submerged, for the purpose of operating on wrecks or performing other undersea duties. This vessel and its successors have bottom doors for the use of divers, as previously stated. They are now used for numerous purposes for which they are much better adapted then the old system of surface diving, the sea bottom being under direct observation and within immediate reach.

This sea bottom, in localities near land, is abundantly sown with wrecks, old and new, and in many cases bearing permanently valuable cargoes, such as gold and coal. The Lake system greatly simplifies the work of search for sunken ships, the vessels being able in a few hours’ time to search over regions which would have taken months in the old method. Many wrecks have been found by these bottom-prowling scouts and valuable material recovered. Thus vessels laden with coal have been traced that had been many years under the water and deeply covered with sand and silt, and their cargoes brought to the surface.

A Semi-submersible Wrecking Apparatus

The gold-dredging spoken of refers to the working of gold-bearing sands found at the mouth of certain rivers in Alaska and South America. Places on the Alaskan coast, laid bare at high tide, are said to have yielded as much as $12,000 per cubic yard. With the Lake system it is possible to gather material from such localities to a depth of 150 or more feet, the material being drawn up by suction pumps into the vessel and its gold recovered.

Another important application is that of fishing for pearl shells, sponges and coral. This is blind work when done by divers from the surface, the returns being largely matters of chance. By aid of submerged boats, with their powerful electric lights, the work becomes one of certainty rather than of chance. The recovery of the oyster, clam and other edible shell-fish is also a feature of the work which the Lake Company has in view. The present method of dredging is of the hit or miss character, while the submarine method is capable of thorough work. Vessels have been designed for this purpose with a capacity of gathering oysters from good ground at the rate of 5,000 bushels per hour. In regard to submarine engineering, of its many varieties, the Lake system is likely to be a highly useful aid and assistance.

These particulars are given to show that the submarine vessel is not wholly an instrument of frightfulness, as indicated by its use in war, but is capable of being made useful for many purposes in peace. Some of these have here been very briefly stated. With continued practice its utility will grow, and by its aid the sea bottom up to a certain depth may become as open to varied operations as is the land surface.

The Story of the Panama Canal

America has captured the forces of Nature, harnessed the floods and made the desert bloom, builded gigantic bridges and arrogant skyscrapers and bored roadways through solid rock and beneath water, but the most spectacular of all spectacular accomplishments is the Panama Canal.

Some four centuries ago, Balboa, the intrepid, the persevering, led his little band of adventurers across the Isthmus of Darien, as it was then called, and, leaving their protection, gave rein to his impatience by going on ahead and climbing alone, slowly and painfully, the continental divide, from which vantage point he discovered the world’s largest ocean.

We are told that, later, gathering his followers, he walked out into the surf and with his sword in his right hand and the banner of Castile in his left gave the vast expanse of water its present name and claimed all the land washed by its waves the lawful property of the proud country to which he owed allegiance.

The narrowness of the Isthmus naturally suggested the cutting of a waterway through it. It interposed between Atlantic and Pacific a barrier in places less than fifty miles wide. To sail from Colon to Panama—forty-five miles as the bird flies—required a voyage around Cape Horn—some ten thousand miles. Yet it was nearly four centuries before any actual effort was made to construct such a canal.

In 1876 an organization was perfected in France for making surveys and collecting data on which to base the construction of a canal across the Isthmus of Panama, and in 1878, a concession for prosecuting the work was secured from the Colombian Government. In May, 1879, an international congress was convened, under the auspices of Ferdinand de Lesseps, to consider the question of the best location and plan of the canal.

The Panama Canal Company was organized, with Ferdinand de Lesseps as its president, and the stock of this company was successfully floated in December, 1880. The two years following were devoted largely to surveys, examinations and preliminary work. In 1889 the company went into bankruptcy and operations were suspended until the new Panama Canal Company was organized in 1894.

The United States to the Rescue.

The United States, not unmindful of the advantages of an Isthmian Canal, had from time to time, made surveys of the various routes. With a view to government ownership and control, Congress directed an investigation, with the result that the Commission reported, on November 16, 1901, in favor of Panama and recommended the lock type of canal, appraising the value of the rights, franchises, concessions, lands, unfinished work, plans and other property, including the railroad of the new Panama Canal Company, at $40,000,000. An act of Congress, approved June 28, 1902, authorized the President of the United States to acquire this property at this figure, and also to secure from the Republic of Colombia perpetual control of a strip of land not less than six miles wide across the Isthmus and the right to excavate, construct and operate and protect thereon a canal of such depth and capacity as would afford convenient passage to the largest ships now in use or which might be reasonably anticipated.

Later on a treaty was made with the Republic of Panama whereby the United States was granted control of a ten-mile strip constituting the Canal Zone. This was ratified by the Republic of Panama on December 2, 1903, and by the United States on February 23, 1904. On May 4, 1904, work was begun under United States control.

Uncle Sam’s Big Work at Panama

A bird’s-eye view of the great canal, showing how the Atlantic and Pacific Oceans are here joined.

[19]

Courtesy of The Ingersoll Rand Company.

Drilling Rock, Panama Canal

These powerful steam drills are capable of sinking holes in the solid rock at the rate of seven feet per hour.

The Canal and the Navy.

The opening of the canal has greatly increased the effectiveness of the Navy of the United States. It has reduced the distance between the central points of the Atlantic and Pacific coasts from 13,000 to 5,000 miles and greatly reduced the problem of coaling on a cruise from coast to coast. It has made possible the concentration of a fleet at either entrance of the canal which, with a cruising speed of fifteen knots, could reach the center of the Pacific coast in nine days and the center of the Atlantic coast in five days.

Where, formerly, the fleets stationed opposite the middle of each coast were, from a cruising point of view, as far apart as opposite sides of the world, they are now as near as if one were off New York and the other off Buenos Aires.

With regard to the monetary saving to the United States resulting from the availability of the canal for naval use, it is apparent that the distance and time between the coasts have been reduced to less than two-fifths of the former figures. The cost of coast-to-coast movements is reduced accordingly, for though vessels of the Navy pay tolls, such payment is in effect a transfer of money from one branch of the government to another.

The strategic importance of the canal is inestimable from a monetary standpoint.

The Great Canal.

The Isthmus of Panama runs east and west and the canal traverses it from Colon on the north to Panama on the south in a general direction from northwest to southeast, the Pacific terminus being twenty-two miles east of the Atlantic entrance. The principal features of the canal are a sea-level entrance channel from the east through Limon Bay to Gatun, about seven miles long, five-hundred-foot bottom width and forty-one-foot depth at mean tide. At Gatun the eighty-five-foot lake level is obtained by a dam across the valley. The lake is confined on the Pacific side by a dam between the hills at Pedro Miguel, thirty-two miles away. The lake thus formed has an area of 164 square miles and a channel depth of not less than forty-five feet at normal stage.

At Gatun ships pass from the sea to the lake level, and vice versa, by three locks in flight. On the Pacific side there is one lowering of thirty feet at Pedro Miguel to a small lake fifty-five feet above sea level, held by dam at Miraflores, where two lowerings overcome the difference of level to the sea. The channel between the locks on the Pacific side is five hundred feet wide at the bottom and forty-five feet deep, and below the Miraflores locks the sea-level section, about eight miles in length, is five hundred feet wide at the bottom and forty-five feet deep at mean tide. Through the lake the bottom widths are not less than one thousand feet for about sixteen miles, eight hundred feet for about four miles, five hundred feet for about three miles and through the continental divide from Bas Obispo to Pedro Miguel, a distance of about nine miles, the bottom width is three hundred feet. The total length of the canal from deep water in the Caribbean, forty-one-foot depth at mean tide to deep water in the Pacific, forty-five-foot depth at mean tide, is practically fifty miles, fifteen miles of which are at sea level.

The Hydroelectric Station.

The hydroelectric station uses water from Gatun Lake for driving three turbo-generators of 2,000-kilowatt capacity each, which supply electricity for the operation of the lock and spillway machinery, the terminal shops and adjacent facilities, and for the lighting of the locks and the canal villages and fortifications. Transmission over the Zone is effected through four substations and a connecting high voltage transmission line which follows the main line of the Panama Railroad.

[21]

Submarines Used in Defending the Panama Canal

The vessels here shown are used in defense of the Pacific side of the canal. They appear as anchored in the new concrete docks at Colon, preparatory to their passage through the canal, after having made the longest sea voyage then on record for submarines.

Copyright by Underwood & Underwood, N. Y.

[22]

Copyright by the International News Service.

Through the Panama Canal

The U. S. battleship Ohio in the east chamber of the Pedro Miguel Locks. On the left is seen the electric locomotive used in drawing vessels through.

[23]

Ladder Dredge, Panama Canal

Suction Dredge, Panama Canal

The upper view shows a ladder dredge, which operates by means of buckets on a continuous chain, dipping the contents of the buckets into the scow which lies alongside. The lower view shows a suction dredge, which operates on soft