Men in normal health should be able to stand a pressure of seventy-six pounds to the square inch and this would call for a depth of 178 feet under water surface, which far exceeds any depth worked under compressed air. For a long time one hundred feet were regarded as a maximum depth and at that depth men were not permitted to work more than an hour in one shift. The ordinary subaqueous tunnel pressure is about forty-five pounds and this corresponds to a head of 104 feet. In working in the Hudson Tunnels the pressure was scarcely ever above thirty-three pounds, yet many suffered from the "bends."

What is called a freezing method is now proposed to overcome the water in soft earth tunneling. Its chief feature is the excavating first of a small central tunnel to be used as a refrigerating chamber or ice box in freezing the surrounding material solid so that it can be dug out or blasted out in chunks the same as rock. It is very doubtful however, if such a plan is feasible.

The greatest partly subaqueous tunnels in the world are now to be found in the vicinity of New York. The first to be opened to the public is known as the Subway and extends from the northern limits of the City in Westchester County to Brooklyn. The oldest, however, of the New York tunnels counting from its origin is the "McAdoo" tunnel from Christopher Street, in Manhattan Borough, under the Hudson to Hoboken.

This was begun in 1880 and continued at intervals as funds could be obtained until 1890, when the work was abandoned after about two thousand feet had been constructed. For a number of years the tunnel remained full of water until it was finally acquired by the Hudson Companies who completed and opened it to the public in 1908. Another tunnel to the foot of Cortlandt Street was constructed by the same concern and opened in 1909. Both tunnels consist of parallel but separate tubes. The railway tunnels to carry the Pennsylvania R. R.

under the Hudson into New York and thence under the East River to Long Island have been finished and are great triumphs of engineering skill besides making New York the most perfectly equipped city in the world as far as transit is concerned.

The greatest proposed subaqueous tunnel is that intended to connect England with France under the English Channel a distance of twenty-one miles. Time and again the British Parliament has rejected proposals through fear that such a tunnel would afford a ready means of invasion from a foreign enemy. However, it is almost sure to be built. Another projected British tunnel is one which will link Ireland and Scotland under the Irish Sea. If this is carried out then indeed the Emerald Isle will be one with Britain in spite of her unwillingness for such a close a.s.sociation.

England already possesses a famous subaqueous tunnel in that known as the Severn tunnel under the river of that name. It is four and a half miles long, although it was built largely through rock. Water gave much trouble in its construction which occupied thirteen years from 1873 to 1886. Pumps were employed to raise the water through a side heading connecting with a shaft twenty-nine feet in diameter. The greatest amount of water raised concurrently was twenty-seven million gallons in twenty-four hours but the pumps had a capacity of sixty-six million gallons for the same time.

The greatest tunnel in Europe is the Simplon which connects Switzerland with Italy under the Simplon Pa.s.s in the Alps. It has two bores twelve and one-fourth miles each and at places it is one and one-half miles below the surface. The St. Gothard also connecting Switzerland and Italy under the lofty peak of the Col de St. Gothard is nine and one-fourth miles in length. The third great Alpine tunnel, the Arlberg, which is six and one-half miles long, forms a part of the Austrian railway between Innsbruck and Bluedenz in the Tyrol and connects westward with the Swiss railroads and southward with those of Italy.

Two great tunnels at the present time are being constructed in the United States, one of these which is piercing the backbone of the Rockies is on the Atlantic and Pacific railway. It begins near Georgetown, will pa.s.s under Gray's peak and come out near Decatur, Colorado, in all a length of twelve miles. The other American undertaking is a tunnel under the famous Pike's Peak in Colorado which when completed will be twenty miles long.

It can clearly be seen that in the way of tunnel engineering Uncle Sam is not a whit behind his European compet.i.tors.

CHAPTER X

ELECTRICITY IN THE HOUSEHOLD

Electrically Equipped Houses--Cooking by Electricity--Comforts and Conveniences.

Science has now pressed the invisible wizard of electricity into doing almost every household duty from cleaning the windows to cooking the dinner. There are many houses now so thoroughly equipped with electricity from top to bottom that one servant is able to do what formerly required the service of several, and in some houses servants seem to be needed hardly at all, the mistresses doing their own cooking, ironing, and washing by means of electricity.

In respect to taking advantage of electricity to perform the duties of the household our friends in Europe were ahead of us, though America is pre-eminently the land of electricity--the natal home of the science.

We are waking up, however, to the domestic utility of this agent and throughout the country at present there are numbers of homes in which electricity is employed to perform almost every task automatically from feeding the baby to the crimping of my lady's hair in her scented boudoir.

There is now no longer any use for chimneys on electrically equipped houses, for the fires have been eliminated and all heat and light drawn from the electric street mains. A description of one of these houses is most interesting as showing what really can be accomplished by this wonderful source of power.

Before the visitor to such a house reaches the gate or front door his approach is made known by an annunciator in the hall, which is connected with a hidden plate in the entrance path, which when pressed by the feet of the visitor charges the wire of the annunciator. A voice comes through the horn of a phonograph asking him what he wishes and telling him to reply through the telephone which hangs at the side of the door.

When he has made his wants known, if he is welcome or desired, there is a click and the door opens. As he enters an electrically operated door mat cleans his shoes and if he is aware of the equipments of the house, he can have his clothes brushed by an automatic brush attached to the hat-rack in the hall. An escalator or endless stairway brings him to the first floor where he is met by the host who conducts him to the den sacred to himself. If he wishes a preprandial cigar, the host touches a segment of the wall, apparently no different in appearance from the surrounding surface, and a complete cigar outfit shoots out to within reach of the guest. When the gong announces dinner he is conducted to the dining hall where probably the uses to which electricity can be put are better exemplified than in any other part of the house. Between this room and the kitchen there is a perfect electric understanding. The apartments are so arranged that electric dumbwaiter service is operated between the centre of the dining table itself and the serving table in the kitchen. The latter is equipped with an electric range provided with electrically heated ovens, broilers, vegetable cookers, saucepans, dishes, etc., sufficient for the preparation of the most elaborate house banquet. The chef or cook in charge of the kitchen prepares each dish in its proper oven and has it ready waiting on the electric elevator at the appointed time when the host and his guest or guests, or family, as the case may be, are seated at the dining table. The host or whoever presides at the head of the table merely touches a b.u.t.ton concealed on the side of the mahogany and the elevator instantly appears through a trap-door in the table, which is ordinarily closed by two silver covers which look like a tray. In this way the dish seemingly miraculously appears right on top of the table. When each guest is served it returns to the kitchen by the way it came and a second course is brought on the table in a similar manner and so on until the dinner is fully served. Fruits and flowers tastefully arranged adorn the centre of the dining table and minute electric incandescent lamps of various colors are concealed in the roses and petals and these give a very pretty effect, especially at night.

Beneath the table nothing is to be seen but two nickel-plated bars which serve to guide the elevators.

Down in the kitchen the cooking is carried on almost mechanically by means of an electric clock controlling the heating circuits to the various utensils. The cook, knowing just how long each dish will require to be cooked, turns on the current at the proper time and then sets the clock to automatically disconnect that utensil when sufficient time, so many minutes to the pound, has elapsed. When this occurs a little electric bell rings, calling attention to the fact, that the heat has been shut off.

Another kitchen accessory is a rotating table on which are mounted various household machines such as meat choppers, cream whippers, egg beaters and other apparatus all electrically operated.

There is also an electric dishwasher and dryer and plate rack manipulator which places the dishes in position when clean and dried.

The advantages of cooking by electricity are apparent to all who have tested them. Food cooked in an electric baking oven is much superior than when cooked by any other method because of the better heat regulation and the utter cleanliness, there being absolutely no dust whatever as in the case when coal is used. The electric oven does not increase the temperature nor does it exhaust the pure air in the room by burning up the oxygen. The time required for cooking is about the same as with coal.

The perfect cleanliness of an electric plate warmer is sufficient to warrant its use. It keeps dishes at a uniform temperature and the food does not get scorched and become tough.

Steaks prepared on electric gridirons and broilers are really delicious as they are evenly done throughout and retain all the natural juices of the meat; there is no odor of gas or of the fire and portions done to a crisp while others are raw on the inside. In toasting there is no danger of the bread burning on one side more than on the other, or of its burning on either side and a couple of dozen slices can be done together on an ordinary instrument at the same time. The electric diskstove, flat on the top, like a ball cut in two, can be also utilized as a toaster or for heating any kettles or pots or vessels with flat bottoms.

Very appetizing waffles are made with electric waffle irons, because the bottom and top irons are uniformly heated, so that the irons cook the waffles from both sides at the same time.

Electric potato peeling machines consist of a stationary cylinder opened at the top for the reception of the potatoes and having a revolving disk at the bottom. The cylinder has a rough surface or is coated with diamond flint, so that when the disk revolves the potatoes are thrown against the sides of the cylinder and the skin is sc.r.a.ped off. There is no deep cutting as when peeled by a knife, therefore, much waste is avoided. While the potatoes are being sc.r.a.ped, a stream of water plays upon them taking away the skins and thoroughly cleansing the tubers.

Among other electric labor savers connected with the culinary department may be mentioned floor-scrubbers, dish-washers, coffee-grinders, meat choppers, dough-mixers and cutlery-polishers, all of which give complete satisfaction at a paltry cost and save much time and labor.

A small motor can drive any of these instruments or several can be attached and run by the same motor. The operation of an ordinary snap switch will supply energy to electric water-heaters attached to the kitchen boiler or to the faucet. The instantaneous water heater also purifies the water by killing the bacteria contained in it.

The electric tea kettle makes a brew to charm the heart of a connossieur. In fact all cooking done by electricity whether it is the frying of an egg or the roasting of a steak is superior in every way to the old methods and what accentuates its use is the cleanliness with which it can be performed. And it should be taken into consideration that in electric cooking there is no bending over hot stoves and ranges or a stuffy evil smelling smoky atmosphere, but on the contrary, fresh air, cleanliness and coolness which make cooking not the drudgery it has ever been, but a real pleasure.

Let us take a glance at the laundry in the electrically equipped house.

There is a large tub with a wringer attached to it and a simple mechanism by which a small motor can either be connected with the tub or the wringer as required. The washing is performed entirely by the motor and in a way prevents the wear and tear a.s.sociated with the old method of scrubbing and rubbing done at the expense of much "elbow grease." The motor turns the tub back and forth and in this way the soapy water penetrates the clothes, thus removing the dirt without injuring or tearing the fabric. In the old way, the clothes were moved up and down in the water and torn and worn in the process. By the new way it is the water which moves while the clothes remain stationary.

When the clothes are thoroughly washed, the motor is attached to the wringer and they are pa.s.sed through it; they are completely dried by a specially constructed electric fan. Whatever garments are to be ironed are separated and fed to a steel roll mangle operated by a motor which gives them a beautiful finish. The electric flat iron plays also an important part in the laundry as it is clean and never gets too hot nor too cold and there is no rushing back to replenish the heaters.

One is not obliged to remain in the room with a hot stove, and suffer the inconveniences. No heat is felt at all from the iron as it is all concentrated on the bottom surface. It is a regular blessing to the laundress especially in hot weather. There is a growing demand in all parts of the country for these electric flat-irons.

Electricity plays an important role in the parlor and drawing-room.

The electric fireplace throws out a ruddy glow, a perfect imitation of the wide-open old-fashioned fireplaces of the days of our grandmothers. There are small grooves at certain sections in the flooring over which chairs and couches can be brought to a desired position. When the master drops into his favorite chair by the fireplace if he wishes a tune to soothe his jangled nerves, there is an electric attachment to the piano and he can adjust it to get the air of his choice without having to ask any one to play for him. In the drawing-room an electric fountain may be playing, its jets reflecting the prismatic colors of the rainbow as the waters fall in iridescent sparkle among the lights. Such a fountain is composed of a small electric motor and a centrifugal pump, the latter being placed in the interior of a basin and connected directly to the motor shaft. The pump receives the water from the basin and conveys it through pipes and a number of small nozzles thus producing cascades. The water falling upon an art gla.s.s dome, beneath which are small incandescent lamps, returns to the basin and thence again to the pump. There is no necessity of filling the fountain until the water gets low through evaporation.

When the lights are not in colored gla.s.s, the water may be colored and this gives the same effect. To produce the play of the fountain and its effects, it is only necessary to connect it to any circuit and turn on the switch. The dome revolves by means of a jet of water driven against f.l.a.n.g.es on the under side of the rim of the dome and in this way beautiful and prismatic effects are produced. The motor is noiseless in operation. In addition to the pretty effect the fountain serves to cool and moisten the air of the room.

The sleeping chambers are thoroughly equipped. Not only the rooms may be heated by electricity but the beds themselves. An electric pad consisting of a flexible resistance covered with soft felt is connected by a conductor cord to a plug and is used for heating beds or if the occupant is suffering from rheumatism or indigestion or any intestinal pain this pad can be used in the place of the hot water bottle and gives greater satisfaction. There is a heat controlling device and the circuit can be turned on or off at will.

There are many more curious devices in the electrically equipped house which could they have been exhibited a generation or so ago, would have condemned the owner as a sorcerer and necromancer of the dark ages, but which now only place him in the category of the smart ones who are up to date and take advantage of the science and progress of the time.

CHAPTER XI

HARNESSING THE WATER-FALL

Electric Energy--High Pressure--Transformers--Development of Water-power.

The electrical transmission of power is exemplified in everything which is based on the generation of electricity. The ordinary electric light is power coming from a generator in the building or a public street-dynamo.

However, when we talk in general terms of electric transmission we mean the transmission of energy on a large scale by means of overhead or underground conductors to a considerable distance and the transformation of this energy into light and heat and chemical or mechanical power to carry on the processes of work and industry. When the power or energy is conveyed a long distance from the generator, say over 30 miles or more, we usually speak of the system of supply as long distance transmission of electric energy. In many cases power is conveyed over distances of 200 miles and more. When water power is available as at Niagara, the distance to which electric energy can be transmitted is considerably increased.

The distance to a great extent depends on the cost of coal required for generation at the distributing point and on the amount of energy demanded at the receiving point. Of course the farther the distance the higher must be the voltage pressure.

Electrical engineers say that under proper conditions electric energy may be transmitted in large quant.i.ty to a distance of 500 miles and more at a pressure of about 170,000 volts. If such right conditions be established then New York, Chicago and several other of our large cities can get their power from Niagara.

In our cities and towns where the current has only to go a short distance from the power house, the conductors are generally placed in cables underground and the maximum electro-motive force scarcely ever exceeds 11,000 volts. This pressure is generated by a steam-driven alternating-current generator and is transmitted over the conductors to sub-stations, where by means of step-down transformers, the pressure is dropped to, say, 600 volts alternating current which by rotary converters is turned into direct current for the street mains, for feeders of railways and for charging storage batteries which in turn give out direct current at times of heavy demand.

That electric transmission of energy to long distances may be successfully carried out transformers are necessary for raising the pressure on the transmission line and for reducing it at the points of distribution. The transformer consists of a magnetic circuit of laminated iron or mild steel interlinked with two electric circuits, one, the primary, receiving electrical energy and the other the secondary, delivering it to the consumer. The effect of the iron is to make as many as possible of the lines of force set up by the primary current, cut the secondary winding and there set up an electromotive force of the same frequency but different voltage.

The transformer has made long distance the actual achievement that it is. It is this apparatus that brought the mountain to Mohammed. Without it high pressure would be impossible and it is on high pressure that success of long distance transmission depends.

To convey electricity to distant centres at a low pressure would require thousands of dollars in copper cables alone as conductors. To ill.u.s.trate the service of the transformer in electricity it is only necessary to consider water power at a low pressure. In such a case the water can only be transmitted at slow speed and through great openings, like dams or large ca.n.a.ls, and withal the force is weak and of little practical efficiency, whereas under high pressure a small quant.i.ty can be forced through a small pipe and create an energy beyond comparison to that developed when under low pressure.