Science of home and community, a text-book in general science

Front matter

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Preface

Education for the present life of the child shotild be the chief purpose of otir schools. This book seeks to cany out this principle so far as science is concerned. We are living in the midst of a great scientific age. Applications of science more and more dominate our life, and they will continue to do so in ever-increasing degree. Any sane system of education must see to it that boys and girls living in the midst of these applications, which form such an important part of their everyday life, are educated in terms of this environment, in order that they may better appreciate it and adapt themselves to it. This book is an attempt to make clear to boys and girls answers to some of the questions naturally arising in their minds concerning the common applications of science.

The book is not written as an introduction to, or preparation for, any later science work. It is written to meet the present needs and interests of boys and girls just entering the adolescent period. We do not know the future of the child, but we do know his present. The satisfaction of these present needs is the best possible and the only sound foundation for any further work in science that he may do in later years.

If a course in General Science is to be worthy of an established place in the school ctirricultun, it mtist fulfill two requirements : first and foremost, it must appeal to the pupils ; and second, it must be well organized around centers of children's interests. *

460007

VI PREFACE

The author has tried to meet these two requirements by finding the basis for both the selection and the organization of material in the applications of science to the child's immediate life. It seems best to group these applications around two great centers, the home life and the commtmity life. There are certain phases of science that are more conspicuous in the home circle, while there are other phases that are more prominent as one goes out into community life. These phases are closely interrelated, and in some cases no sharp line can be drawn between them ; but the author believes that from the child's standpoint this division forms a natural basis for organizing the text.

The material has been organized from the human rather than from the scientific point of view. The child sees first the uses made of various things, then he is interested to tmderstand something of the construction and mode of operation of the machines involved, and finally he wishes to know what their history has been. Consequently the great inventions have been treated from the four standpoints of their uses, their history, their construction, and their working.

This is not a textbook in General Science in the sense that it attempts to cover a little of all the sciences, just for the sake of covering them all. The extent to which any particular science is included depends on the part that the science plays in the immediate life of the child. Whether any particular science or any particular topic in a science should form a part of the course depends on the number and value of the elements that it possesses in common with the child's life. As a matter of fact, the two sciences that are especially conspicuous in the child's daily life, and hence dominate the text, are physics and hygiene.

The author acknowledges his indebtedness to the following firms for their courtesy in allowing illustrations from their publications to be used as copy for illustrations made for this book: American Book Co., The Century Co., Doubleday,

PREFACE VU

Page and Co., E. P. Button and Co., Everybody's Magazine, Ford Motor Co., Ginn and Co., Harper and Brothers, The Norman W. Henley Publishing Co., George W. Jacobs and Co., J. B. Lippincott Co., A. C. McClurg and Co., Frederick A. Stokes Co., Whitcomb, and Banams. The illustration of the first telephone is taken, with Mr. Casson's permission, from his book, " History of the Telephone."

G. H. T.

Mankato, Minn.

4 ■

NOTE TO TEACHERS

The practical work outlined in this book has been divided into four kinds : laboratory exercises, demonstrations, field exercises, and projects. The demonstrations are to be done before the class either by the instructor or by some pupil. It is intended that the laboratory exercises shall be performed by each pupil. The extent to whicb each pupil can do the laboratory exercises will depend on the equipment and the facilities available for individual work. If equipment is lacking, the laboratory exercises may be performed as demonstrations. The field exercises are to be done by the instructor and class outside of the schoolroom. In the projects something is provided for each pupil to do individtially outside of the laboratory. These projects have been divided into three groups: for the home, for the school, and for the commimity. They provide a vital kind of work because they connect the school work with actual life and provide opportunity for the pupil to do something on his own responsibility. It is suggested that a certain n\miber of home projects be required of each pupil, who may be allowed to choose the ones he wishes to carry on. The pupils should be expected to present definite written reports of the projects and should be given school credit for the work done. A sufficient variety of projects has been given so that each pupil can find some suited to his circttmstances.

The author believes that the pupils should make some written records of all the practical exercises. These records, kept in a notebook, should be brief and simple in form. It is suggested that each record may contain, first, a statement

ix

X NOTE TO TEACHERS

of the ptirpose of the exercise ; second, a brief description of what was done; and third, a statement of the things learned or the conclusions drawn from the exercise.

Questions at the beginning of each chapter are given as problems to guide the pupils in their study. These, together with the questions at the end of the chapter, are suggested as a basis for the class discussions. It is believed that a few leading questions of this type will stimulate the pupils to independent thought and to organization of their knowledge.

In order to adapt the work to the individual interests and capabilities of the pupils, it seems desirable that students mal^e reports to the class on some subjects of which they have made special study. As an aid in this line of work a few references are given at the close of each chapter. . The stress to be laid on the various chapters depends on the environment of the pupils, whether it is urban or rural. In accordance with this environment some chapters may be passed over lightly, while others should receive special attention.

Part I. Science Op The Home

SECTION A. HYGIENE OP THE HOME

PAGE

I. Heating the Home 3

II. Ventilating the Home 17

III. Lighting the Home . . , 33

IV. The Home Water Supply 45

V. The Hygiene of the Dining Room ... 58

VI. Science of the Kitchen 98

SECTION B. PLEASURE IN THE HOME

VII. Musical Instruments 118

VIII. Taking Pictures . . . . . . .1^6

IX. House Plants 138

SECTION C. ELECTRICITY IN THE HOME

X. Applications of Electricity 148

SECTION D. ySE OP THE HOME GROUNDS

XI. The Ornamentation of the Home Grounds . 161

XII. The Vegetable Garden 180

XIII. The Pruit Garden 203

XIV. Poultry Keeping and Bee Keeping . . .214

XV. Attracting Birds around the Home . . . 226

xi

Xii TABLE OF CONTENTS

Part II. Science Of The Community

SECTION A. MEANS OF TRAVEL

Group A. Travel on Land

XVI. The Locomotive .... . . . 245

XVII. The Electric Trolley 257

XVIII. The Automobile 266

Group B. Travel by Water XIX. The Steamboat and Submarine .... 284

Group C, Travel by Air XX. Airships and Airplanes 300

SECTION B. MEANS OF COMMUNICATION

XXI. The Telegraph 318

XXII. The Telephone 333

SECTION C. THE HEALTH OP THE COMMUNITY

XXIII. The Public Water, Milk, and Food Supply . 347

XXIV. Contagious Diseases 365

XXV. Insects and Disease 394

XXVI. Health Officers 417

XXVTI. School Hygiene 426

SECTION D. COMMUNITY ENTERTAINMENT XXVIII. The Moving Pictures . . . . . . 444

SECTION E. CONSERVATION OF COMMUNITY RESOURCES

XXIX. Protection of Birds 459

XXX. Conservation of Forests 478

• • •

TABLE OF CONTENTS XUl

SECTION F. PROTECTION FROM WEATHER XXXI. The United States Weather Bureau . . . 503

SECTION G. RELATION OF EARTH TO THE OTHER

HEAVENLY BODIES

XXXII. The Earth as a Part of the Solar System . 515

SECTION H. AN ENEMY OF HOME AND COMMUNITY

XXXIII. Alcoholic Drinks 536

Appendix

Table of Relative Humidity 555

List of Apparatus 556

Table of Inventions 557

PART I

SCIENCE OF THE H©ME

• a -ft 4 V '

SCIENCE OF HOME AND

COMMUNITY

SECTION A Hygiene of the Home

Chapter I Heating The Home

1. In what ways are our present modes of heating better than those used in early times ?

2. What advantages has each of the following methods of heating the home : hot air, hot water, and steam ?

Early methods of heating. People have become so accustomed to the methods now used to heat their homes that they do not often stop to think that these same methods have not always been used and that a hundred years ago people did not have the same conveniences for heating that we now enjoy. Our present methods of heating, as well as nimierous other conveniences, have come to us only gradually after many changes and improvements i\mning back htmdreds of years. Let us consider briefly the changes in methods of heating that have taken place from the very earliest times up to the present day.

The first method of heating used by primitive man many centuries ago was to build a fire on the earth floor of his crude hut and allow the smoke to escape through a hole in

'4 ' \:2CSS^Ct OF HOME AND COMMUNITY

• * •

.y. : '-tlvB^top'-oK ih<i htjt. ^- As there was no chimney, the smoke was often blown down the opening and filled all parts of the hut. This method was probably used for thousands of years.

The primitive fireplace. When the first chimney was built the fire was moved to one side of the room, a hole was cut in the wall just over It, and a hood was made that projected out over the fire to collect the smoke. A little later this was improved by making a recess in the wall for the fireplace and building a separate chimney to carry off the smoke. By the end of the fifteenth century these fireplaces were in common use throughout the civilized world. For two hundred years after the settlement of this country by white people, they depended entirely upon the open fireplace to warm their homes during the cold winters. In the early days the churches were not heated at all.

Primitive stoves and furnaces. The next improvement in heating was the invention of the stove. At first it consisted of an iron box provided with openings at the top for the escape of the smoke, which passed out into the room. Charcoal was often burned in it, as that did not give off much smoke. The next step was to connect a pipe with this box to carry the smoke outdoors. The first stove of this type was made about two hundred years ago.

Stoves were first used in this country about fifty years before the Revolutionary War. About thirty-five years before this war (in 1742) Benjamin Franklin invented the stove that was named after him. The Franklin stove was a box with metal sides and entirely open in front. It was set in the fireplace and connected with the flue of the chimney. This was a great improvement over the fireplace. Other improvements were continually made until the modem stove that we use to-day was developed.

The next great advance made in heating was the plan of placing a single large stove, called a furnace, in the

HEATING THE HOME S

cellar and heating the entire house by means of this. The first furnaces were used only about one hundred yea^ ago.

Modem heating. The modern fireplace. Fireplaces are stiU frequently built into houses, both because they are ornamental and because the open fire is attractive. Dtu*- ing the late spring and early fall, when it is not cold enough to start the furnace, these fireplaces serve a useful purpose in taking oflE the chill during the evening ; but as a means of heating, the fireplace is ineffective and expensive. It is ineffective because it raises the air near it to an extremely high temperature, while the air in distant parts of the room is heated only slightly; it is expensive because so much heat is wasted in the heated air that passes up the chimney, and a large amount of fuel is required to keep the fire going. It is not adapted to cold climates.

The modern stove. The stove is a great improvement on the fireplace in that it warms the room more satisfactorily and requires less fuel. The stove heats the room by a process called convection. The heated air over the stove rises and circulates to other parts of the room, while the colder air rushes in over the stove and is heated. By this means a larger part of the air of a room is heated than would be possible by a fireplace. While in the fireplace the fuel is burned in the open, frequently filling the room with smoke, in the stove the fuel is burned in a closed firebox with a special pipe for carrying off the smoke. The stove has the further advantage that it is provided with dampers by* means of which the fire may be controlled. When coal is first put into the stove, the back damper should be opened to allow the escape of poisonous gases that form, as otherwise these may be forced back into the room. Cook stoves are so built that th^ heated gases may be forced to pass around the oven, thus heating it before passing up through the pipe and chimney.

The hot-air furnace. One disadvantage of heating by stoves lies in the fact that several stoves are needed to warm the whole house. Hence, systems are now very widely used in which the whole house is heated from one furnace located in the cellar, the heat being carried to the various

rooms by means of either hot air, or hot water, or steam. The hot-air furnace is a large stove surrounded with a metal jacket, with' space between to allow air to circulate. Air is brought into this inclosed space by a duct leading from outdoors, from the cellar, or from the rooms above ; and as it passes over and arotmd the furnace it becomes heated. The furnaces are constructed so as to give a large heating surface. From the top of the air jacket, pipes lead to the several rooms to conduct the hot air through registers placed either in the floor or on the walls near the floor. Frequently these pipes are covered with asbestos to reduce the loss of heat. Each pipe usually has a damper near the furnace and a register in the room that may be opened or closed, by means of which the hot air supply may be shut off from one part of the house and sent to other rooms.

Fig. I. — Hot-air system.

HEATING THE HOME ^

The drctdation of dir through these pipes is maintained through the effect of heat on gases. When air is heated it expands and so becomes Ughter, while the air coming in from outdoors is colder and heavier. When two gases of unequal weight are brought into contact, the tendency is for the heavier body to sink to the bottom and push the lighter gas up. So here the cold air rushes in tmder the warm air, which is thus forced upwards.

Demonstration i

Purpose. To study the principles applied in the hot-air furnace.

Apparatus. Flask, rubber stopper with a single hole to fit, glass tubing about a foot long, alcohol lamp or Bunsen btimer, tumbler, chimney, touch paper or piece of cloth, candle.

Directions, i. Push the glass tubing through the hole in the stopper and insert the stopper in the flask. Fill the tumbler with water and place the end of the tube in it. Heat the flask gently and notice what happens at the end of the tube. What is the explanation ? Remove the lamp but allow the end of the tube to remain in the water. Explain what happens.

2. Light a candle. On the table on each side of the candle put a match ; on the matches place a lamp chimney. Light a joss stick or piece of cloth and hold at the lower end of the chimney near the matches. What do you notice inside of the chimney ? What does this show ?

3. How are the principles illustrated by these two experiments applied in the hot-air furnace ?

The hot-water system. In the hot-water system the water is heated in the basement by the furnace and is then conducted through pipes to radiators situated in the various rooms. (See figure 2.) In the attic is placed a tank connected with this set of pipes. The hot water passes to this tank and to the radiators, and then back to the fiunace, where it is reheated.

The explanation of the circulation of the water is similar

to that of the drctilation of the air in the hot-air system.

When water is heated, it expands and becomes lighter and

is pushed up by the cold water, which descends to the furnace

where it is reheated, thiis keeping a constant circulation of

water through the pipes.

This is called the direct

method of heating.

In another method of heating, the coils containing the hot water are placed in the basement, and fresh air from outside is drawn ia and heated and then distributed to the various rooms by means of pipes and registers, as in the hot-air system. This is called the iWiVerf method of heating. (See figure 5.) This system has an advantage over the direct Fig. ,. - Hot-^tec system. method in that it provides

better ventilation.

In still another system the radiators are placed in each room as in the direct method, and an opening from outside near the radiators brings in fresh air, which is heated by passing over the radiators. This is called the direct-indirect method. (See figure 6.)

Deuonstsation 2

Purpose. To study the principles applied in hot-water heating.

Apparatus. Flask, stopper and tube used in previous experiment, two flasks with two-hole rubber stoppers, two pieces of glass tubing about ten inches long.

HEATING THE HOME

Directions, i. Fill the flask with water and insert the stopper so that water stands in the tube about an inch from the stopper. Tie a colored string around the tube at the surface of the water. Heat the flask and watch the liquid in the tube. Remove the lamp and allow the water to cool. What happens to the water in the tube in each case ? What does this show ?

2. Secure two flasks, one a little smaller than the other. Break a hole in the bottom of the smaller one. Fill the larger flask with water and insert a rubber stopper with two holes. Through these holes push two pieces of glass tubing about ten inches long. Push in one tube until it just passes through the stopper. Push in the other tube about halfway to the bottom of the flask. Invert the other flask, insert a rubber stopper with two holes and push in the ends of the glass tubings. Add water until the upper ends of the tubing are covered. Add a few drops of red ink. Heat the lower flask and notice the circtdation of the water.

3. How are the principles illustrated in these two experiments applied in the hot-water heating ?

Steam heating. The method of heating by steam is similar to the hot-water method except that steam instead of hot water circulates. There is a similar system of radiators connected by pipes with the furnace. At the furnace the boilers are so arranged that the water is ^ ^ ^ ,

, ^ . ^ ^ ^ . , Fig. 3. — A steam-heating system.

changed mto steam, which

then circulates through the pipes. The same indirect

method, as explained imder the hot-water systan, and likelO SCIENCE OF HOME AND COMMUNITY

wise the direct-indirect method explained above may be used.

The source of the heat in the steam is due not merely to the fact that the steam is hot, but largely to the fact that when steam condenses it gives off a large amount of heat. When water is boiled, it takes a large amount of heat to change it into steam. When we wish to measure the amoimt of heat, we use a standard called the calorie, as we use the poimd to measure weight. A calorie represents the amoimt of heat necessary to raise the temperature of one gram of water one degree Centigrade. It requires over five htmdred calories to change one gram of water into steam, that is, over five times the amount of heat needed to heat water from the freezing point to the boiling point. This heat is stored up in the steam,, and when the steam condenses, the heat is given out to surroimding objects. It is the condensing of steam that furnishes most of the heat. Provision is made for pipes to take the water thus formed back to the furnace.

Purpose. To learn the source of heat in the steam-heating system.

Apparatus. Flask, rubber stopper with one hole, piece of glass tubing about eighteen inches long, beaker, ringstand, thermometer.

Directions. Bend the tubing twice at right angles so that the two arms are parallel and point in the same direction. One of these arms should be about three inches long, and the other arm about eight inches long. Fill the flask a third full of water and insert a rubber stopper with one hole. Push the short arm of the tubing through the hole in the stopper. Support the flask on a ringstand. Fill a beaker with cold water and place it so that the long arm of the tubing dips below the surface of the wQter in the beaker. Take the temperature of the water. Heat viie water in the flask. After it has boiled five minutes, take

HEATING THE HOME II

the temperature again of the water in the beaker. How much has the temperature changed? What was the source of this heat?

The hot-water sj^tem has one great advantage over the steam system in that the water can be heated to any desired temperature and thus can be easily regulated in the mild weather; while in the steam system the water must be heated to the boiling point before any results are obtained, and in mild weather it is difficult to keep the temperature sufficiently low.

Home Project i

Purpose. To make a study of the heating system used in your home.

Directions, i. If your house is heated by hot air, steam, or hot water, make a careful study of the different parts of the system. Begin with the furnace and notice where the various pipes lead, and trace the circulation of air, water, or steam through the house and back to the furnace. Make a drawing of a section of the house from the garret to the cellar, showing the different parts of the system in their proper position.

2. Make a study of a cook stove when there is no fire in it, so that it can be taken apart. Make a drawing of a cross section of the stove. Label in the drawing the following parts; ash pan, grate, draft damper, oven damper, oven clean out. By means of black arrows show the path of the smoke and products of combustion around the oven and up the flue when the oven damper is up. By means of red arrows show the path when the damper is down. Notice how the stove may be cleaned out.

Heating by electricity. The latest improvement in heating is the use of electricity. This method is very convenient and does away with the smoke and dirt of stoves and furnaces. At present it is just in its beginnings and is now too expensive for common use. In the future, improvements will doubtless be made and electricity will be' sold at a lower price, hence it is qtiite possible that a hundred years from now, electricity naay be the common method of heating. As %he stoves and furnaces of to-day have taken the place of the fireplaces formerly in common use, so in the future, electric radiators may take the place of stoves and furnaces.

The chemistry of burning. The source of heat in any of these systems, excepting electricity, is the burning of the fuel. In coal the chief element is carbon. In wood, too, this is found, together with other elements including a gas called hydrogen,which also bums. The burning of coal consists in the union of the oxygen of the air with the carbon, forming an invisible gas called carbon dioxid, and consists to a lesser extent in a union with hydrogen, forming water. In breathing we give oflE the same gas, which is formed in our bodies in a similar way, but not so rapidly, by the union of oxygen and carbon. This process of uniting with oxygen takes place in all ordinary types of burning, as in the candle and the kerosene lamp.

Fuels are of three kinds : solid, such as coal and wood ; liquid, such as kerosene ; and gaseous, such as illuminating gas. Coal and wood are the fuels most commonly used for heating purposes.

Coals are divided into two classes, the hard and the soft. The hard coal contains a larger per cent of carbon, and the soft coal a larger per cent of volatile substances that are driven off when the coal is heated. These substances are not completely burned, and as a result a large amotmt of smoke is formed. In order that the fire may continue to bum, the various products formed must be carried off through the chimney ; and a new supply of oxygen must be furnished. The fire is controlled by means of dampers which regulate the amount of air that enters. The important part of the air for the purpose of burning is oxygen. This constitutes about one fifth of the air. Experiments with pure oxygen

HEATING THE HOME 13

show that substances bum much more vigorously in it than in air.

Before a substance will bum, it must be heated to a certain temperature called the kindling temperature. In kindling fires, substances are first used with a low kindling temperature, such as paper, then this sets fire to a substance with a higher kindling temperature, like wood, and finally the wood in burning heats up a substance like hard coal with a still higher kindling temperature, till it, too, bums.

Purpose. To prepare oxygen and study its properties.

Apparatus. Test tube, glass tubing about eighteen inches long, pneumatic trough, four wide-mouthed gla^s bottles, potassium chlorate, manganese dioxid, oxone, sulfur, iron picture wire, deflagrating spoon.

Directions. A, Preparation of oxygen, i. Fill the test tube half full of a mixture of equal parts of potassium chlorate and manganese dioxid. Insert a stopper with a hole. Bend the glass tube about three inches from one end to make an acute angle, and at the same distance from the other end bend it to make an obtuse angle. Insert the end with the acute angle in the hole of the stopper, and put this in the test tube. Support the tube on the ring of a ringstand. Place the other end of the tube under the shelf of the pneumatic trough. Fill the trough with water to cover the shelf. Fill four wide-mouthed bottles with water and invert on the shelf. '

2. Heat the test tube gently, allowing the first bubbles to escape. Then place one bottle with the mouth over the opening in the shelf so as to collect the gas. When the water has all been forced out, remove the bottle and put another in its place. In this way fill four bottles.

3. In place of potassium chlorate and manganese dioxid oxone may be used. The advantage of using this is that it is not necessary to heat the substance. It may be placed in a bottle and when water is added, oxygen is given off at once.

B. Properties of oxygen, i. Invert one of the bottles and put in it a burning splint. How does the action compare with that in the air? Potir in a little limewater, shake the bottle. The white precipitate shows the presence of carbon dioxid.

2. Fasten a wire to a candle, light the candle and plunge it into a second bottle. Note results.

3. Put some powdered sulfur in a deflagrating spoon. Ignite it in a flame and then lower it in a third bottle. Note the difference between burning in air and in oxygen.