GIFT OF Agriculture education GENERAL SCIENCE AND THE ECONOMICS OF DAILY LIFE BROWNELL A TEXTBOOK IN GENERAL SCIENCE AND THE ECONOMICS OF DAILY LIFE BY HERBERT BROWNELL, B. Sc. PROFESSOR OF SCIENCES IN SECONDARY EDUCATION, TEACHERS COLLEGE, UNIVERSITY OF NEBRASKA, LINCOLN; AUTHOR OF "LESSONS IN PHYSICS", "LESSONS IN CHEMISTRY", AND "LABORATORY LESSONS IN GENERAL SCIENCE" WITH 118 ILLUSTRATIONS PHILADELPHIA P. BLAKISTON'S SON & CO. 1012 WALNUT STREET COPYRIGHT, 1918, BY P. BLAKISTON'S SON & Co. / ( r ry; THK MAPI, K I K K s S YORK PA PREFACE A science, as the term is usually employed, implies a group- ing of the facts and phenomena of some one field of human knowledge according to certain general statements known as theories and laws. Botany, for instance, is a classification of man's knowledge of plants, and of the conditions for their growth. It makes possible the study of plants in groups rather than one by one. But in General Science as a high school subject selections of topics for study are made from any and all of the secondary school sciences. These topics are studied for the general purpose of giving scientific explanations to whatever affects daily life in so far as they lend themselves readily to elemen- tary scientific discussions. Some theory is given as needed in these explanations, but there is little or no regard to whether the facts and explanations have to do with any one science or another. Sufficient experimental phenomena are to be provided in laboratory exercises and classroom demon- strations. The topics are supposed to be more or less familiar through the common experiences of childhood and youth, and of such a nature as to foster a scientific spirit. This text seeks to relate for schoolroom uses the teachings of science and the common experiences of life. Its dis- cussions are designed to stimulate a desire on the part of pupils for information concerning everyday phenomena readily obtainable from high school science texts, and from reference books suited for use in elementary science teaching. Some of the discussions of the text though elementary in character will present difficulties for beginners. But the v 387901 vi PREFACE author believes it advantageous early in the course to make some use of the theories of high school science in order to give scientific unity to explanations of various common phenomena. Care has been exercised to distinguish sharply at all times between fact and theory, and to make clear the restrictions that must accompany the use of theories whether in school or elsewhere. Enough of a knowledge of the differentiated high school sciences should be gained in a general science course to serve as a real introduction to them. This will enable pupils later to make an intelligent choice of which of these sciences they care to pursue. However skillfully information for beginners in science may be selected and presented, it will fail very largely of its purposes as " knowledge-making material" if no need for it has arisen in the minds of pupils, and if no apparent use for it exists. Where a desire for knowledge is based on needs that have been experienced, it calls forth effort in the school- room even as it does in the larger field of life experiences. A purpose of the text is to arouse and in some large measure to guide the desires of pupils for a scientific understanding of life's problems, and to furnish some of the material and con- ditions necessary to secure these ends. Perhaps foremost of all the ends sought in the teachings of General Science is an habitual scientific attitude of the pupils the state of mind that demands the facts in all cases; that discriminates in the relative importance and pertinence of facts; that can so associate them as to get their chief significance whether in specific relationships or in gen- eral applications; that does not rest satisfied with "glittering generalities" but tests them out to ascertain if theory fits facts when applied to known conditions and existing situa- tions. In other words, the facts of the discussions in General Science, valuable as they may be in themselves, are to be PREFACE Vll used for the larger purpose of establishing a scientific pro- cedure in the affairs of life. The author desires to express his deep appreciation of the helpful suggestions and criticisms of those who have read the manuscript for this text, or portions of it. Special acknowledgments are due Dr. R. J. Pool of the Department of Botany; Professor H. C. Filley of the Department of Farm Management; Professor Alice M. Loomis of the Department of Home Economics; Professor George E. Love- land, Director of the U. S. Weather Bureau; Professor G. D. Swezey of the Department of Astronomy; and Dr. R. A. Lyman of the Department of Physiology, all of the Univer- sity of Nebraska, together with Professor B.C. Hendricks of the Department of Physics in the State Normal School at Peru, Nebraska. He is under special obligation to Professor A. E. Sheldon, Lecturer on Political History and Secretary of the State Historical Society, and to Mrs. Sheldon, for their very helpful criticisms in their readings of the manu- script. The author assumes, however, all responsibility for errors that may have crept into the text. Aside from acknowledgments made in connection with single illustrations, the author wishes to express his apprecia- tion for other illustrations from : U. S. Forest Service, Figs. 37 40, 76, 83, 84, 86, 88. U. S. Weather Bureau, Figs. 32, 48, 102. U. S. Public Health Service, Figs. 15, 21, 25. U. S. Public Roads and Engineering, Figs. 29, 69. U. S. Reclamation Service, Figs. 38, 39. U. S. Geological Survey, Figs. 92, 112. Division of Publications, U. S. Department of Agriculture, 18, 24, 26, 27 28, 36, 47, 67 68, 73, 75, 77, 79, 80, 81, 82, 85, 93, 95> 96, 97, 98, 103, 104, 105, 106, 107, 108, in. CONTENTS PAGE I. SOME LESSONS ON THE HUMAN BODY. The Hand 2 The Mouth 4 The Eye 10 II. HEAT IN RELATION TO THE HUMAN BODY. Combustion 16 Pure Air, and Breathing 19 The Human Body as an Engine, and the Regulation of Body Temperature 25 III. HEALTH AND WELL-BEING. Keeping Well 31 Infection 36 Sanitation 45 The Water Supply and Health 52 General Health Problems 57 Life, Growth, Rest, and Recreation 64 Stimulants and Narcotics 72 General Science and Right Living 80 IV. WATER AND ITS USES. Some Properties of Water 85 Vaporization and Condensation 90 Heat of Vaporization and of Fusion 94 Solution, Diffusion, Absorption, and Osmosis 97 Streams, Valley Formation, and Surface Erosion 102 V. THE ATMOSPHERE. Properties and Uses of Air no Pressure Exerted by the Atmosphere, and Effect of Pressure on Gases 114 Applications of Atmospheric Pressure 118 Currents in the Atmosphere, and Their Relation to Atmospheric Pressure 123 Areas of High and Low Pressure 128 ix X CONTENTS PAGE VI. WEATHER AND CLIMATE. Weather in the Affairs of Men 133 Weather as Affected by Highs and Lows 137 The Thermometer, and Heat Transmission 140 Solar Heating 147 -,yil. MATTER AND FORCE. Some Properties of Matter, and Changes in Matter Due to Force 151 VIII. WORK AND MACHINES. Meaning of the Terms Work and Energy 160 *Levers and Pulleys 163 Electromagnets 168 IX. SOME CHEMISTRY OF EVERYDAY LIFE. A Review of Some Chemical Changes 173 *The Chemistry of Cleaning . 177 *Acids, Bases, and Salts A . . 180 *Electricity and Chemical Changes 184 "Limestone and Other Carbonates 190 *The Chief Among Metals 196 X. AT OUR HOMES. Rooms of the House, Their Furnishings, and the Cost of Living 206 Fuel and Lights for Modern Homes 214 Some Foodstuffs 219 * The Carbohydrates . . 226 Fires, Burns, and Various Accidents 233 XI. SURROUNDINGS OF THE HOME. The Garden, and Its Care . . . . . 241 Soil Conditions for Plant Growth 247 Tree Planting *-'. . . . 254 Trees of the Neighborhood 259 Some Plant Studies 263 Usefulness of Plants to Man 268 Birds Around Our Homes 275 XII. SOME CONDITIONS AFFECTING INDUSTRIAL LIFE. Changes in Manner of Living 281 Social and Economic Conditions Affecting the Wage Earner . . 290 *See page 372. CONTENTS xi PAGE XIII. THE FARM. Poultry and Eggs 297 The Horse 304 Cows, and the Dairy Industry 307 Lessons on Corn 312 Apple Raising as an Industry 319 Wheat, and Wheat Growing . 325 Origin and Nature of Soils 332 XIV. PHENOMENA OF LIGHT. Shadows and Eclipses 336 *Images by Reflection in Plane Mirrors 338 *Color Phenomena , 342 XV. THE EARTH AS A PLANET. Day and Night, and the Earth's Rotation 349 Rotation Combined With Revolution, and Changes in Seasons 351 The Moon, and Its Phenomena 355 Time, and Time-keeping, and Standard Time . . . . . . .359 XVI. THE HEAVENS 364 APPENDIX. Suggestions to Teachers 370 Reference Books 372 * See page 372. GENERAL SCIENCE I. SOME LESSONS ON THE HUMAN BODY 1 INTRODUCTION We expect a surgeon to have an intimate knowledge of human anatomy, and a physician to be skilled in human physiology. But enough of the anatomy and physiology of the human body should be taught in schools so that in- struction in hygiene as a study of health conditions will be better understood by every one, and its teachings better observed. The importance of an understanding of health conditions, and of their control, is emphasized in the lessons that follow, as are the relations between good health and the happiness of mankind. The lessons on the Hand, Mouth, and Eye are given because of the peculiar usefulness to man of these important organs of his body. No one should be ignorant of their structure and uses and care. A large part of the knowledge of the world around us is gained through the eyes and hands, and life's activities are largely dependent upon their services. Then, too, the progress of man in civilization and much of his enjoyment is intimately associated with oral speech in which the structure of the 1 In Zoology as a study of all forms of animals, including human beings, anatomy deals largely with the structure of the body, while physiology has to do with the activities of the various organs. Botany as a study of plants likewise has its subdivisions of anatomy and physiology. Biology is the science of living bodies, and includes both Botany and Zoology. I 2 GENERAL SCIENCE . mouth plays a most important part. Some knowledge of Human Physiology as studied in schools is presupposed in these lessons. THE HAND The bones of the hand serve as a framework, giving to it both form and strength. The many joints of the hand and wrist make possible a great variety of movements, and a wide adaptability in uses. The bones are held together at the joints by ligaments, and the surfaces of bones that move upon each other are covered by cartilage. A study of both cartilage and ligaments can be made from a joint obtained at a meat shop. Motion in the parts of the hand and wrist is accomplished by means of muscles, the "lean meat" of animals. Sometimes the muscles are attached directly to the bones, seeming to grow out of the bone itself. In the wrist and hand the movement of cord-like tendons beneath the skin may be seen and felt. The muscles here are at some distance from the bones moved by them, and are connected to the bones by the tendons. To cause these muscles to act, moving the hand and fingers or holding them at rest as a person desires, the muscles are provided with nerves. In the skin of the inner part of the hand and fingers the terminal fibres of the nerves are so close that the hand through care and training may acquire a FIG. i. Bones of the right fore- arm, a, palm; b, back of hand; r,r', radius; u, u f , ulna. SOME LESSONS ON THE HUMAN BODY 3 marvelous delicacy of touch. The blind learn to read through their finger tips, and players of the violin and other musical instruments seem almost to think with their fingers, so intimate is the relation of muscle and mind through the nerves. The hair, finger nails, and outer layers of the skin are all destitute of blood vessels. Growth in them occurs only at their under surfaces and inner ends. The tendons and ligaments, too, get a scant supply of blood, and their repair is slow after accidents where a sprain has occurred, or when they have been torn from the bone. Either condition may be more serious than a broken bone, or the dislocation of bones at a joint. The finger nails serve to support and protect the ends of the fingers, and to enable a person to pick up small objects more readily. At all times they should be kept neatly trimmed, and scrupulously clean. The fold of skin at the base of the nail should be kept pushed back instead of being cut off. Food should never be handled with unwashed hands, nor the finger tips touched to the tongue. The hand is man's chief instrument for labor. He uses it for feeding and dressing himself. It is a weapon for self- defense, and is a means for fashioning tools, implements, clothing, and for preparing his food. It is in almost constant use during man's waking hours, ministering to his needs and executing his desires. SUMMARY In shapeliness, structure, and adaptability the hand is a wonderful tool fashioned for man's use. In its varied movements is illustrated the fact that the muscles are the organs of motion in the body. These muscles move in obedience to impulses sent outward to them from nerve centers, the chief of which is the brain. The ability of man to labor and to care for himself is seriously im- paired when he is deprived of his hands. His mind, too, is robbed of GENERAL SCIENCE t the stimulus of directing those activities in which the hands are em- ployed, and of those reactions which result from expression of thought through hand work. THE MOUTH The cavity known as the mouth is not only the beginning of the digestive canal, but it is one of the chief organs of speech. In Physics from the study ^of sound we learn something of the uses of the mouth and its adjacent parts in talk- ing and in singing. Complete control of the muscular parts of the mouth and its connected cavities is necessary to a singer in order to give utterance to sounds in their proper relationship in the musical scale. Just above the larynx, and embedded in the tissues, there may be felt on either side of the neck the small semi-elliptical hyoid bone. From it many of the mus- cular fibres of the tongue arise. It does not connect with other bones of the < ,1 i T skeleton the only case of the kind in ^ Q body. As a movable bdS6 it gives to the tongue an exceedingly wide range of movement. Back of the mouth cavity and the at- tached end of the 'tongue is another cavity with muscular walls known as the pharynx (far'-inks). This is the upper enlarged extremity of the muscular food tube, or oesophagus, which leads to the stomach. Food and drink, when forced by the tongue back into the pharynx, pass over the glottis, or entrance to the larynx, and are kept from getting into it by a cartilaginous cover known as the epiglottis. Cough- ing, strangling, and choking mark spasmodic efforts to dis- lodge food or drink that gets into the glottis. Once within FIG. 2. Hyoid bone, h\ trachea, t; bronchi, b, b'\ larynx, I; glottis, g. SOME LESSONS ON THE HUMAN BODY 5 the pharynx, food and drink are beyond a person's control. Their movement along through the remaining thirty or more feet of the food canal is due to the vigorous activity of the muscular coats of the oesophagus, stomach, and intestines. Taste and smell add much to the enjoyment of living. But the distribution of the nerves of these two senses in the nasal and mouth cavities indicates that their primary pur- pose is to give warning against the introduction into the body of food, drink, or air that is unwholesome or harmful. Not all harmful substances have a bad taste or odor, nor are all substances with disagreeable taste or odor harmful. How- ever, the products of decay in foods when not disguised by spices and flavorings are likely to give evidence of their presence by an unnatural odor or taste. The tonsils are peculiarly exposed to infection. Their location in the throat is such that they are in contact with the air breathed, and with food and drink on its way to the stomach. Their structure, too, is such as to make them sus- ceptible to attacks of germ diseases. Any " soreness" of the throat, and any "patches" upon the tonsils, may necessitate prompt medical treatment. Many of the fatal ailments of childhood manifest themselves in their earlier stages by an inflamed condition of the throat, and more or less of swelling and soreness there. All "colds" should be regarded with suspicion, and proper care and precautions taken from their first appearance. Although air is made to pass in and out of the mouth when talking and singing, and when playing upon some musical instruments, in all ordinary breathing the air should pass to and from the lungs through the nose. In this way cold air becomes somewhat warmed before reaching the lungs. Dust present in the air is largely stopped in the nose, collect- ing on the surface of the moist mucous lining of the nasal cavity and on the hairs just inside the nostrils. 6 GENERAL SCIENCE A child who habitually breathes through the mouth may be afflicted with adenoids, and their removal may become necessary. Catarrh is a persistent congested condition of the mucous lining of the nasal cavity, and may cause deafness. The thorough mastication and insalivation of food is an essential stage in the process of dissolving it. This process is known as digestion. Water or other drinks used to wash down the food do not take the place of the saliva. Man, unlike birds and domestic fowls, has no gizzard to do what the teeth should have done. The saliva contains small portions of a so-called digestive ferment which brings about chemical changes in starchy foods, converting the starch into a form of sugar which dissolves easily. The other digestive fluids also cause chemical changes in foods through the action of the ferments which they contain. A nervous or excited state, or extreme weariness in body or mind, interferes with and may stop the secretion of these digestive fluids 1 , thus impairing digestion. One should not eat at such times, but wait until rested and quieted. A happy frame of mind favors digestive processes. Mealtime should be a time of mirth and social enjoyment, and never a time for controversy and settlement of disputes, or for administering family discipline. The sight, smell, and taste of appetizing food, and a state of unsatisfied hunger, maintains the flow of the digestive fluids. The flow lessens when these conditions cease to exist. Many people attempting to speak in public experience difficulty from dry lips and mouth. Their nervousness causes a less- ened flow of saliva. A dry fevered appearance of the tongue and mouth, and a heavy white or yellowish coating of the tongue, indicate 1 The amount of gastric juice secreted per day may be five pints or more. SOME LESSONS ON THE HUMAN BODY 7 a condition of the mucous lining of the stomach and intestines unfavorable to the secretion of digestive fluids. In such cases one should eat sparingly till normal conditions are restored. Only those foods should be eaten which have been found from experience to be easily digested. Perhaps no one condition connected with the digestion of food is followed by such a train of bodily ills as constipation, especially where it persists during infancy, childhood, and youth. The whole system becomes disordered by reason of any retention and reabsorption of bodily wastes. Igno- rance of what it signifies, and of the course to be pursued permanently to relieve it, spares no one of its evil conse- quences. Dullness of mind, headache, dizziness, a coated tongue, and a foul breath, with more or less of a tired feeling all the time, are some of the common results of constipation. A full easy movement of the bowels daily as an established habit from childhood contributes largely toward health and efficiency for life. Insufficient activity of the muscles of the intestines, a lack in vigor of their wavelike or peristaltic movements, is the immediate cause of constipation. To maintain the conditions favorable for a healthy activity of the bowels may require constant care. Sufficient exer- cise for the muscles of the trunk and abdomen, deep breath- ing, use of plenty of water as a drink between meals 1 , and enough sleep, all contribute to the general health and to a satisfactory elimination of the bodily wastes. Food which repeatedly causes indigestion is to be avoided. Regularity in action of the bowels should, under all ordinary circum- stances, be maintained without recourse to medicines. Meats, eggs, milk, beans, and wheat bread are some of the 1 In addition to the water taken with food at meal times, the habitual prac- tice of drinking between meals a half dozen glasses (three pints) of water daily aids in keeping the body in a healthy condition. 8 GENERAL SCIENCE foods which have a tendency to cause constipation be- cause of lack in bulk. Fruits and vegetables generally, together with graham flour, corn bread, bran foods, and oatmeal, are likely to stimulate the bowels to a normal activity. The enamel of the teeth is the hardest substance in the body. It contains no blood vessels, and when once cracked or broken is not restored by nature. The dense bony mate- rial beneath it, forming the body of the tooth and known as dentine, decays when exposed to the action of bacteria. Protection of the teeth from decay, and their preservation throughout life, necessitates continuous care. Frequent examination by a competent dentist is usually advisable, especially during childhood and youth. It is better to pre- vent decay than to be forced to repair its ravages. There is no satisfactory substitute for a frequent use of the tooth- brush. As the first of the thirty-two teeth in the permanent set may grow into place when children are but six or seven years of age, the habitual use of the brush should begin in early childhood. It is often possible to tell much of a person's state of mind from the expression of the lips and the mouth. The passing emotions of mirth, scorn, or disgust are reflected in one's face. Discontent, brutality, and vulgarity on the one hand, or contentment and sweetness of disposition on the other, stamp themselves indelibly upon the face. Repeated im- pulses in the nerves distributed to the muscles of the face leave their evidences of firmness or fickleness of purpose, strength of character or weakness, in permanent lines formed about the mouth. The kind of feelings cherished, and the manner of thoughts indulged, sooner or later make or mar one's expression. By means of the nerves the varied movements of the numerous muscles of the body are directed and controlled. SOME LESSONS ON THE HUMAN BODY 9 In some cases this is by direct act of the will (mind) 1 , and in other cases such as movements of the muscles of the heart, diaphragm, and intestines, the action is largely or wholly involuntary. It is over the nerves, too, that impulses travel to the brain and other nerve centres giving rise to sensa- tions. Education as "mind development" involves for one thing an increasing readiness in interpreting correctly the significance of sensations. SUMMARY Any study of the mouth cavity must take into account that it is a part of the digestive tract, and a chief organ of speech. It is likewise the chief gateway whereby germ diseases enter the body. The senses of taste and smell may be considered as primarily for the purpose of preventing entrance of injurious and poisonous substances into the body with the food and drink, or with the air breathed. While the tongue as an organ of speech at times may be "an unruly member," its muscles are nevertheless wholly subject to one's control. Its utterances are what we make them. In learning to speak a foreign language there is much the same difficulty experienced in getting the muscles of the tongue to give correct utterance to sounds as there is in bringing under control those of the hand when learning to play musical instruments in correct time and with suitable expression. Sustained and close attention, and much practice, may be necessary to properly co-ordinate mind, nerve, and muscular action. 1 No one is likely to mistake an electric light bulb for the electricity by means of which the mechanism of the bulb produces the illumination. Nor is there any confusion in distinguishing between a dynamo as a machine, and the electrical energy sent out from it. In a similar manner a sharp distinction is to be made between the brain as the organ of the mind on the one hand, and on the other its powers (activities) in interpreting sensations, in noting rela- tionships among these sensations, and in deciding upon a course of action in accordance with the knowledge possessed. Whatever the nature of the brain activity in the processes of thought, and however dependent mental vigor may be upon a well-nourished brain, it simplifies our discussions here to con- sider the mind, and the development and use of its powers, more or less apart from brain phenomena. io GENERAL SCIENCE Great as the value of a good set of teeth may be in the appearance of a person, their primary purpose is their use for the digestion of food. To go through life with teeth made more or less worthless by neglect in childhood is a serious handicap upon health and length of life. THE EYE The human eyes when one stands erect command a wide range of vision without turning the head. The eye is seldom perfect as an optical instrument. Its defects, even when serious, may often easily be remedied by glasses fitted after an examination of the eye by a competent oculist. The eyes of people whose general health is good give a lifetime of excellent service when they have not been subjected to abuse. It is the utmost folly not to give the eyes intelligent care especially during school days. When once the sight is destroyed a person is shut away from much that is in the world about him. His knowledge then be- comes limited largely to what he can hear and touch. To understand how it is that we can know of objects far distant from us, and beyond our reach, requires the study of light as given in Physics. Through the transparent interior of the eyeball light reaches the optic nerve. Its terminal fibres are spread out over the interior of the rear wall of the eyeball and form the retina. Any transparent medium with a curved surface is a lens. Those used in telescopes and microscopes, and in spectacles, are of glass. In the eye the soft, elastic crystalline lens serves to form images on the retina just as the lens of the photographer's camera forms an image on the chemically prepared plate. The cornea (kor'-ne-ah) , the vitreous humor, and the aqueous humor of the eyeball also refract light, i.e., bend it from a straight line course as it passes into and then out of them. An ample supply of blood is furnished to the eyeball, but the humors, lens, and cornea are nourished without dimming SOME LESSONS ON THE HUMAN BODY 1 1 their transparency. Circular musular fibres in the iris by their contraction allow less light to enter the eyeball, and as they relax the pupil of the eye is enlarged. Dust and any foreign particles lodged underneath the eyelids, or an irritation due to lack of tear-water, may cause congestion of the blood vessels in the eyeball and in its surroundings. This gives the eye a temporary blood-shot appearance. Pain in the eyes as elsewhere in the body is nature's warn- ing that something is wrong with the mechanism. Weariness is a signal for rest, or a demand that an abuse of the eyes be stopped. Rest for the eyes when reading, sewing, A ' FIG. 3. Formation of images on the retina of the eyeball. (So far as the physics of the phenomenon is concerned the images thus formed are inverted.) % or using the microscope, does not necessitate complete dis- use of the eyes. Any occupation that requires sustained effort to see the same object, especially if dimly lit up, soon wearies the eyes. Looking at other objects at different distances rests the eyes. The little muscles that hold the lens of the eye in a particular form in order to see any ob- ject distinctly are often kept under a strain which not only wearies but weakens them. The effect is somewhat the same as when one forces himself to hold his arm out horizontally from the body for a long time. Any serious ailment of the eyes calls for their examination and possible treatment. Glasses fitted by oculists, while commonly for the purpose of 12 GENERAL SCIENCE enabling persons to see more distinctly, are quite as often prescribed to relieve eyestrain. Changes in the eyeball it- self naturally occur as a person grows older, making necessary the wearing and the refitting of glasses from time to time. That objects at different distances may be seen distinctly, changes in the form of the crystalline lens are continuously FIG. 4. The workers here are not likely to have impaired eyesight. taking place. This adjustment in form is known as the power of " accommodation, " and it is more or less completely lost in old age. A whole train of bodily ailments often attend upon or are caused by eyestrain. Headaches, nervous exhaustion, and impaired digestion are often directly traceable to it. Im- patience and ill-temper may arise from it. No one should be ignorant of what constitutes right conditions for continu- ous use of the eyes, especially any close application of them. SOME LESSONS ON THE HUMAN BODY Reading when weary, or when on trains, or when lying down, severely taxes the eyes and should be avoided. Large re- sponsibilities rest upon architects and builders whose business it is to arrange both for the artificial and for the natural lighting of the rooms and buildings in which people are to live and work. It is not especially important that objects in front of pupils in schoolrooms, and of workers in offices and shops and homes, shall be illuminated by light that "comes over the left shoulder." But the illumination must be neither too bright nor too dim, and the light must be so uni- formly diffused that sharply outlined shad- ows do not exist in the room. Any con- scious effort in excluding light from the eyes because it is too glaring, or in making out details of objects viewed because the light is too dim, is evidence of something wrong with the illumination of the room. No direct rays of light should be allowed to come into the eyes either from the sun or from electric bulbs. The contraction of the pupil to shut out the excess of light from an unscreened lamp shining directly into one's eyes may result in eyestrain, since too little light can then enter them from the objects upon which one is at work. The glare of the lights of an automobile blinds one to other objects near at hand that are not brightly lit up, because the size of the pupil of the eye adjusts itself to the more intense light. FIG. 5. Hard on the eyes. 14 GENERAL SCIENCE School requirements for use of the eyes are at times ex- acting but these requirements are never sufficient excuse for permanent impairment of vision, nor for long-continued eyestrain. Since schools do demand so much in a sustained use of the eyes, it is the more necessary that all contributing causes to weakened eyesight such as late hours, motion pic- tures, etc., be largely avoided. Special care should be given to maintain good health, and when necessary to be correctly fitted with glasses. Under no circumstances should use of the eyes upon difficult work, or under unfavorable con- ditions, be continued after the eyes have become inflamed, or have begun to ache from use, or when headache occurs from eyestrain. SUMMARY While the eye as an optical instrument may be conside ed perfect in its design, it is probable that relatively few people are free of defects in eyesight. Most such defects are of minor character, and may oftentimes be ignored. However, when the general health is impaired, or when excessive and exacting use is made of the eyes, these defects may become serious. Impaired eyesight is a handicap in life's activi- ties and in its enjoyments. Intelligent care of the eyes requires a knowledge of their structure, their defects, and their proper use. Eyestrain may be caused by dim lighting, by too glaring lights, and by unequal diffusion of light. Fatigue and exhaustion of the whole nervous system may follow, upsetting the equilibrium of the body organism and resulting in a disordered state of the nerves and a loss of mental poise. The small muscles whose office is to hold the crystalline lens in that particular form where vision is most distinct become exhausted by long-sustained close application, such as in reading fine print, in continuous use of the microscope, and in doing fine sewing. This strain is relieved if from time to time the eyes are used in looking at other and more distant objects. Many headaches from which people suffer are directly or indirectly caused by eyestrain. SOME LESSONS ON THE HUMAN BODY Pupils not infrequently acquire at school the bad habit of stooping or bending over their books. This strains the eyes by bringing them too close to the print. Twelve inches is about the proper distance. Exercises 1. By what means is a wide variety in movement of hand and fingers secured? 2. Tell the location, form, manner of growth, and uses of the finger nails. 3. Name several of the structures within the hand of which something can be learned by inspection though they are hidden from view. 4. Define (a) tonsillitis; (b) adenoids. 6. What information concerning the state of one's health can be learned from the appearance of the tongue? In what sense is the tongue an organ of digestion? 6. Describe (a) the hyoid bone as to its position and use; (b) the pharynx as to position and structure. 7. Why do the teeth ache? How is nourish- ment conveyed into a tooth? 8. How does a singer become able to produce any note desired in singing PIG. 6. Tests for astigma- and a speaker to utter any desired tism. Hold the cut at a suitable sound in speech? distance from the eyes and in A a good light. Note if the 9. About what is the diameter of the eye- parallel lines in all directions ball (a) side wise; (b) up and down? appear equally distinct. By a drawing indicate the relative size and form of the upper and lower eyelids as seen when the eye is "open." 10. What usually becomes of the tear-water that drains off into the nose through the tear-duct? How are the frequent movements of the eye- lids caused? What is meant by saying that these movements are commonly "involuntary?" 11. What are common defects in the eyeballas an optical instrument? 12. What is generally true of the eyesight when it is once harmed by reckless or ignorant use of the eyes? Explain the purpose of the ciliary (sil'- e-ar-e) muscles. State how they become weakened, and how this may be avoided without disuse of the eyes. II. HEAT IN RELATION TO THE HUMAN BODY COMBUSTION For a complete understanding of the changes known as combustion one must study Chemistry. Combustion com- monly means oxidation, i.e., union with oxygen (O), accom- panied by noticeable heat and light as result of the chemical change. Coal is largely carbon (C), and when it burns (oxidizes) one of the products is a gas known as a carbon dioxide whose chemical formula is CO 2 . When the gas hydrogen (H) is burned, the product is water (H 2 O). Paraffine, tallow, wood, kerosene, and many other substances used for fuel and lights, contain carbon and hydrogen in their chemical com- position. When burned they yield both water and carbon dioxide as the principal products of their combustion. Oxy- gen exists free in the air mixed with about four times its volume of nitrogen. Oxygen as an element in water is so much heavier than hydrogen that eight-ninths by weight of all water is oxygen. It is calculated that oxygen constitutes about one-half the weight of the chemical compounds forming the rocks of the earth's crust. One of the most important teachings of chemistry is that the same substance is always made up of the same chemical elements, and that these are always united in the same propor- tions by weight. The compound known as water has the 16 HEAT IN RELATION TO THE HUMAN BODY 17 formula H 2 O whether it is a liquid, or a solid such as ice and snow and frost, or the invisible vapor present at all times in the air about us. The relative weights of oxygen and hydrogen in it remain unchanged. When coal burns with a limited supply of oxygen a poi- sonous gas called carbon monoxide (CO) forms. In the pres- ence of more oxygen this gas burns with a bluish flame form- ing carbon dioxide. This flame is often seen above a coal fire. The illuminating gas furnished in towns and cities for fuel and lights contains more or less carbon monoxide, and any leakage of gas from burners or from stoves is dangerous because of its poisonous effects as well as its explosive na- ture when mixed with air. Oxidation may go on very slowly wherever uncombined oxy- gen comes in contact with substances with which oxygen unites readily. This slow combustion occurs within water, and it goes on in the cells of the body. The heat liberated in the various tissues ordinarily maintains a temperature of the human body above that of the surrounding atmos- phere. In some animals like the turtle and the snake this oxidation is so slow that they always feel cold when handled because their body temperature is less than that of human beings. In the rusting of such metals as iron, oxidation takes place very slowly; in the explosive mixture of gasoline vapor or of illuminating gas with air, it may be instant and violent. Many of the high explosives used in blasting have in their composition sufficient oxygen to make it possible for combus- tion to occur away from the air. The temperature to which bodies like kerosene, wood, and coal must be brought in order that combustion may occur is called the kindling temperature, or point of ignition. A flame is a burning gas or vapor. A candle flame ceases to exist at its outer surface where combustion is complete. 1 8 GENERAL SCIENCE On the inside the flame begins where the kindling tempera- ture of the supply of gas or vapor has been reached, and where oxygen is available for combustion. The candle flame has the form of a hollow cone, enclosing a cone of vapor that is not burning. The blowpipe flame is hot because the same amount of combustion occurs within a smaller space. The color of different lights is largely due to the kind of material that is incandescent (light giving), and to the tem- peratures to which this material is heated. In the common electric bulb there is no combustion, the bulb having no oxygen inside of it. The temperature of the filaments caused by the electric current is sufficiently high to produce incandescence. SUMMARY The term combustion in opular usage means a case of oxidation where the heat liberated causes burning material to become so hot as to give off light. The products of oxidation are known as oxides. They may be gases as carbon dioxide, or liquids as water, or solids as iron rust. A flame is a gas or vapor that is burning. The combustion may be slow and under control, or it may be instant and explosive in violence. The size of a flame is determined by the distance outward to which the mixture of the gaseous material with air extends. In a candle flame the inner dark cone consist of vapor not burning because of lack of oxygen, and because its temperature is below the point for ignition. The hollow luminous cone is burning vapor, the outermost limits of which are almost colorless by reason of an almost completed combustion. Carbon dioxide gas from the air is used by plants in the manufacture of such materials as sugar, starch, and wood fibre. But it must not be overlooked that plants, like animals, must have a supply of oxygen to maintain their life, and to provide the energy necessary for their growth. The amount of carbon dioxide given off as a product of this plant breathing is, however, insignificant in comparison with the amount converted by the plant into wood, starch, and sugar. HEAT IN RELATION TO THE HUMAN BODY 19 PURE AIR AND BREATHING 1 In order to keep warm and dry men require shelter from the weather. The occupations of many people keep them within doors the year around. As a matter of economy and of comfort during the winter season, dwellings and places of business are guarded against the entrance of the cold outer air. This shuts away the supply of oxygen essential to health. A single gas light exhausts the oxygen of a room and produces FIG. 7. Sleeping porch, and sun parlor. carbon dioxide as fast as the breathing of several persons. So far as need of air is concerned man is an out-of-door ani- mal. The conditions of civilized life have shut him in so closely that health is often impaired, and life itself sometimes sacrificed. About one-third of a person's life should be spent in sleep. For sleep to be most refreshing and invigorating it should be in rooms or porches wide open to the out-of-doors air. Only 1 Respiration as the term is used in biology involves the process of oxidation as it occurs in the cells. It is a function of living cells wherever located. On the other hand the term breathing is restricted to the exchange of gases within and without plants and animals, and is a purely physical process. 20 GENERAL SCIENCE extreme cold or dampness is excuse for sleeping temporarily shut away from an abundance of outside air. An open but well-screened sleeping porch, with a warm room to dress in when the weather is cold, makes quite an ideal condition. During the day the ordinary activities of life render un- necessary any special attention to ventilation save where large numbers of people are together as in public halls, schools, and factories. In these places there is likelihood of oxygen starvation. The air, too, soon becomes laden with moisture from perspiration, and from water in the respired air. Dis- ease germs may be given off into the air from any infected person present. All this makes necessary the continuous renewal of the indoors air. In cold weather air' from out of doors should be warmed before it is allowed to spread through the rooms. There should never be appreciable currents (drafts) in any part of a room. The air should always be free from dust, too, and should contain considerable mois- ture, especially if it is furnace heated. A humidity of from 40 per cent to 50 per cent does not dry the mucous mem- branes of the air passages, nor does it interfere with evapora- tion of the perspiration. To maintain the circulation necessary to bring a continu- ous supply of air into rooms, advantage is usually taken of the fact that air when heated becomes less dense (lighter). The air of a building may be kept in circulation by having one portion warmer than other parts of it. The colder and more dense air presses the warmer air onward and outward. The chapters on heat and pneumatics (nu-mat'-iks) in Physics usually include a study of air currents, and of sys- tems of heating and of ventilating. The satisfactory ven- tilation of the many rooms in large buildings used for offices, stores, factories, or for schoolroom purposes, requires that air be forced into them or withdrawn from them by some me- chanical means, such as fans driven by electricity. This HEAT IN RELATION TO THE HUMAN BODY 21 air in some cases is made to pass through a room where in some one of various ways it is " washed" free of dust and other impurities, and given the desired amount of moisture. In winter it may then be warmed by passing it over steam coils before distribution in the building, and in summer it may be cooled by use of ice. Continuous stirring of air that is not changed in any other way has been found to afford marked relief in ill-ventilated rooms. The movement of the FIG. 8. Framework of the chest walls. In B the chest cavity has been enlarged by the contraction of the rrmscular walls; and in A decreased by the relaxation of these same muscles. air lessens the discomfort and sense of depression occasioned by having warm moisture-laden air remain stagnant around a person. Serving as a partition between the chest and abdominal cavities the diaphragm (di'-a-fram) is attached at its circum- ference to the side walls of the chest. The framework of the chest is made up of the ribs, the spine, and the breast-bone. The muscular fibres of the diaphragm are so arranged that it is flattened downward when they contract, thus crowding the stomach, liver, and intestines outward and enlarging the chest cavity. Not least among the beneficial effects of deep 22 GENERAL SCIENCE breathing, involving as it does the full use of the diaphragm, is the rhythmic pressure exerted downward upon the stomach and liver. This promotes digestion, and tends to prevent constipation. Over the motions of this muscle which is so largely concerned in breathing a person has but slight and indirect control, making the action in large part involuntary. The muscles of the side walls of the chest are, however, largely under control. By throwing back the shoulders, and by causing the muscles be- tween the ribs to contract and pull the ends of the lower ribs apart, the chest cavity can be considerably enlarged at will. An easy erect position, whether sitting or walking, gives larger space for the lungs than where one goes about stooped and with drooping shoulders. Per- sistent efforts to fully inflate the lungs in breathing is one of the ways of maintaining health. It is the unused por- tions of the lungs that are most likely to become diseased. The lung capacity in use is about 200 cubic inches (3200 cc.). Only about one-eighth of this amount passes in and out at each breath 1 . The reserve supply of air not exhaled at every breath serves to prevent sudden changes of tempera- 1 The following tabulation exhibits approximately the air volumes con- cerned in breathing: Air passing in and out at each breath (Tidal Air) 20-30 cu. in. Additional air that can be but seldom is taken in (Comple- mental Air) 120 cu. in. Air that can be forced out after a full inspiration 150-250 cu. in. Air that cannot be driven out (Residual Air) 100 cu. in. FIG. 9. Wrong sitting position. The lungs cannot be fully inflated in breathing. HEAT IN RELATION TO THE HUMAN BODY 23 ture in the lungs as cold air is inhaled, and to prevent death by suffocation when temporary stoppage of the air passages occurs. Air may be rebreathed repeatedly and continue to furnish oxygen to maintain life. But it is to be remembered that exhaled air containing available oxygen may be unfit for use because of the carbon dioxide, water vapor, and waste organic matter in it. The air as inhaled commonly consists of about 21 per cent oxygen, 78 per cent nitrogen, i per cent argon, and 3/100 per cent carbon dioxide gas, along with a varialbe quantity of water vapor and dust particles. The exhaeld air is saturated with moisture, and has approximately 16 per cent oxygen and 5 per cent carbon dioxide, the argon and nitrogen gases remaining unchanged in amount. About one pint of water passes from the body daily as vapor in the breath. The need of ventilation is often apparent to a person enter- ing a schoolroom or public hall when those in the room are unaware of the bad condition of the air. Dullness, rest- lessness in body, headaches, inability to give continuous at- tention, and much of the feeling of irritation experienced by those shut up in schoolrooms oftentimes disappear after a few minutes of exercise indoors with windows wide open. It is to be remarked that cold air is not necessarily pure air, rior do rooms need ventilating because they are comfortably warm. Pure air, however, is no cure for late hours and in- sufficient sleep, or for lack of wholesome food and absence of other conditions essential to sound bodies and bright minds. Artificial breathing in cases of drowning may, if necessary, be successfully maintained for a long period by laying the patient face down, the face turned to one side, and the mouth open to admit free passage of air to and from the lungs. Sitting astride the hips of the patient let some strong person 24 GENERAL SCIENCE alternately apply and then remove pressure upon the lungs through the walls of the chest. This* may be accomplished by holding'the hands against the lower ribs and throwing the FIG. 10. Resuscitation of the drowned expiration in artificial breathing. PIG. ii. Resuscitation of the drowned inspiration in artificial breathing. weight of the body first forward and then backward with about the same rhythm as in natural breathing. SUMMARY Ventilation seeks to secure an ample supply of oxygen for respiration, and at the same time to prevent the air about a person from becoming HEAT IN RELATION TO THE HUMAN BODY 25 unduly laden with moisture, with carbon dioxide, and with organic matter thrown off from the body in the breath. A continuous renewal of the air in closed living rooms, offices, and assembly halls is necessary. The problem of ventilation becomes a serious one only during weather when rooms are kept tightly closed on account of the cold. All unnecessary outlays for heating buildings must be avoided, and all drafts of cold air. Particular attention should be given to securing an abundance of pure air during the hours of sleep. It is a relatively easy matter to provide sufficient bedding to protect against any danger of being chilled while asleep in a room open to out-of-doors air even in the coldest weather. More serious than the dullness of mind and the weariness of body due to oxygen starvation when sleeping in poorly ventilated rooms is the lack of bodily vigor, and the lessened powers of resistance to germ diseases. This menace to health is the greater because the relation- ship is not always apparent, and because the ill consequences are often long delayed. The development of tuberculosis in a person could often have been prevented by the same care that is exercised later in an effort to effect a cure through being much out-of-doors, and by having suitable em- ployment, sufficient exercise, and nourishing food. In the rhythmic rise and fall of the diaphragm nature has provided an important means of continuously stimulating muscular action in the digestive tract, and of preventing constipation. Lung capacity varies much in different persons, and as a rule is con- siderably more in a man than in a woman. It is disuse of the lung capacity, however, that is the really serious consideration. Laziness in breathing should be overcome, but forced and intermittent efforts to do this accomplish but little. There should be enough of active daily exercise to cause a demand by the body for an increased supply of oxygen, thus necessitating deeper breathing. The chances for life at times of choking or of drowning may depend upon the reserve air in the lungs. Everyone should know just how to proceed to resuscitate a drowned person. THE HUMAN BODY AS AN ENGINE, AND THE REGU- LATION OF BODY TEMPERATURE The fact that a person can do work and can move about presupposes the existence of energy by use of which these 26 GENERAL SCIENCE activities and labors are performed. Energy is often denned as that by use of which work is done. Any machine such as an engine, is only a means employed for using energy to do work. The human body comes under this definition, and this conception of the body includes brain activities as well as muscular effort. The human body as a living organism possesses, however, the power of repairing itself under right conditions of liv- ing. If properly cared for, it should neither break down nor wear out till long past the allotted "three score years and ten." As with any other engine the character and quantity of work it can do depends in large measure upon the care it has, and the good judgment exercised in its use. Folly, ignorance, and inex- perience all combine to impair its use- fulness or to wreck it altogether. It is one of the purposes of schools to give in- struction and training in the right uses as a machine may of both body and mind. Success in living break down rather ... than wear out. even as success in business requires the best use of all the means and machinery of life. It is necessary for the well-being of an individual that the bodily processes be under as intelligent control and as constant care as that exercised by an engineer with a locomo- tive, or by a chemist in laboratory experiments. The body like the steam engine depends upon energy lib- erated within it by chemical changes. A considerable por- tion of this energy is used in keeping up the bodily processes. The activities of the heart, digestive organs, brain," and other organs require an expenditure of energy. Deficiency in its amount means imperfect performance or complete ces- sation in their activities. It is chiefly the starchy foods, FIG. 12. The body HEAT IN RELATION TO THE HUMAN BODY 27 sugars, and fats that are body fuels. On the other hand, one- seventh or more of the food needed by the body is required for rebuilding the various tissues. Foods that serve this spe- cial purpose are known as proteins. Starch, sugars, and fats are classed as carbohydrates. The energy from oxidation in the body maintains a temperature necessary for the various organs to perform their several functions (duties) . The chem- ical products of this oxidation in the body, even as in the combustion of coal or oil, are largely carbon dioxide and water. Most of the processes within the body are normally carried on without conscious effort. If it were necessary to give attention to every act in respiration, or to attend to what is now the involuntary action of the heart muscles, little else could be done. One might forget to breathe, or to keep the heart beating regularly. Freed from the necessity of directing the bodily mechanism, the mind can be employed in directing the expenditure of the excess energy of the body in those physical and mental efforts involved in earning a livelihood or in promoting culture, health, and happiness. The living matter contained in the cells of the different body tissues cannot endure any considerable change in tem- perature without harm to it and possible destruction of its life. One of the functions of the skin through secretion of perspiration is to regulate the body temperature so that in health it varies but little summer or winter, regardless of whether one is indoors or out. As the perspiration evaporates from the surface of the body heat is required to vaporize the water. This heat is provided in part from the body, and the more profuse the perspiration and the more complete its vaporization, the larger is the amount of heat taken from the body. The higher the body temperature as result of jnuscular exercise the more active is the secretion of perspi- ration by the glands in the skin. It is nature's provision that 28 GENERAL SCIENCE the more heat there is in the body the more there is disposed of in this way; the lower the body temperature, the less ac- tive is the secretion of perspiration and the less the loss of heat with it. Since the temperature of the body is commonly higher than that of the surrounding atmosphere, there is also a loss of heat direct to the air from the warm body just as in the cool- ing of any other heated object. By use of suitable clothing protection may be had from the dangers incident to chilling the body surface, and depriving the skin of its blood supply. If one gets chilled the internal organs become congested (overfilled) with blood that should have been distributed to the surface and extremities of the body. The regulation of body temperature by the skin is interfered with, and the disordered condition of the body known as a "cold" may result. Oftentimes this develops into dangerous ailments such as pneumonia, or into an inflamed state of organs other than the lungs. Exposure at the throat and upper part of chest is especially dangerous when the lungs are themselves filled with cold air. There should be especial attention given to the cir- culation of blood in the extremities of the body. The feet and hands should be warm at all times. Wet or damp cloth- ing not only wastes body heat by vaporization of the mois- ture, but clothing when damp conducts heat from the body much faster than when dry. After a bath the body should be vigorously rubbed with a dry towel till its surface is com- pletely dry. This avoids any chill due to abstraction of heat from the body as water on the skin vaporizes. The rubbing should result in a redness of the skin. A feeling of warmth, together with a "glow" of the skin, follows an in- crease in the amount of blood sent to the body surface as result of the irritation produced by the rubbing. The chill experienced when leaving over-heated rooms, or crowded HEAT IN RELATION TO THE HUMAN BODY 29 assembly halls with their moisture-laden air, may be due in part to the evaporation of perspiration from the clothing. SUMMARY The human body as an instrument for doing work may very properly be considered a machine. Its care in order to secure the largest service from it requires a degree of intelligence surpassing that needed generally in the management of machinery. Conditions must be maintained favorable to its repair through growth. Undue destruction of its parts by excessive or improper use must be avoided. Proper balance must be maintained between its waste and repair. Any impairment of the powers of the body is a serious handicap throughout life. The harm due to ignorance is just as serious as though done by deliberate choice. Much of the ill-health of later life, and many of the limitations of the body in its usefulness as a machine, are often directly traceable to an unwise manner of living during childhood and youth. All motion occurring in the body in the performance of work involves an expenditure of energy. All the activities of digestion, respiration, and circulation, together with those of the brain and nervous system as a whole, require a supply of energy without which the bodily proc- esses would cease. The temperature of the body is maintained by chemical changes within the body known as oxidation. Any considerable departure from a normal temperature of 98 F. makes impossible, too, a continu- ance of the bodily processes, and death results. One of the chief functions of the skin is the regulation of body temperature by disposing of any excess of bodily heat in the vaporiza- tion of perspiration. When by reason of old age, wasting disease, impaired digestion or assimilation, the temperature of the body runs much below normal, extra clothing must be worn and warmth from without the body must be provided. Colds may result from a bodily state of depression due to fatigue. At such times germs lodged in the lungs and nasal passages are given opportunity for rapid development because of the lessened powers of resistance of the body. Colds may be the result of a congested and inflamed condition of the nasal passages, stomach, intestines, or kid- neys, due to an excessive blood supply sent to them at a time when the surface of the body is thoroughly chilled. Whatever promotes an 30 GENERAL SCIENCE active circulation of the blood in all parts of the body, and whatever contributes to the general good health, aids in the prevention of colds. Exercises 1. To what is the color of candle and lamp flames largely due? What is the nature of the " smoke" from chimneys? 2. What significance has the presence of carbon dioxide gas in the breath? 3. In ventilating rooms and buildings, what special attention must be given (a) to economic considerations; (b) to danger to health? 4. What is meant by a flame? Why is there greater danger of accident in the use of gasoline than of kerosene? 5. State some ways of showing that the interior of a candle flame is not afire. 6. In which parts of plants is carbon dioxide gas changed chemically into material for plant structure and nourishment? What relation to this change has sunlight? 7. Why is there need to give less attention ordinarily to the ventilation of living rooms by day than by night? Why is there need of more attention in winter than in summer? 8. In tuberculosis of the lungs what at present is the only hopeful course of treatment? When only is this successful? What conditions in living are conducive to this ailment? 9. About what on an average is (a) the rate of respiration; (>) the capacity of the lungs; (c) the per cent of the lung capacity employed at a breath? 10. What advantages (a) in the gradual change of the air in the lungs; (b) in the retention in them at all times of considerable air? 11. What good purpose is served by habitual deep breathing? What are the ill effects from habitually failing to inflate the lungs fully at every breath? 12. Describe the steps to be taken for the resuscitation of a drowned person. Give the reason for each step. 13. What is the apparent relation between vigorous exercise whether as work or play, rapidity of breathing and of heart action, and the temperature of the body? 14. In what sense does perspiration "regulate" the temperature of the body? 15. What is the meaning of the terms {a) congestion; (b) inflammation? 16. Why is there risk to one's health from damp feet or clothing when not exercising? 17. What relation apparently exists between temperature maintained in the body and the continuance of life activities? Explain this. 18. What is the purpose (a) of the digestion of food; (b) of the oxidation of portions of it? III. HEALTH AND WELL-BEING KEEPING WELL Our control over our health is much like that exercised by gardeners and florists over the growth of their plants. Neglect or improper care is ruinous in either case. Health and disease are essentially conditions of the cells of the body, and of the fluids about the cells. Our mastery of health lies in maintaining the right conditions. A knowledge of " nature's laws" is of little purpose unless our manner of life is made to accord with them. Our un- willingness to do what must be done in order to promote and to maintain health will not protect us from the consequences of not working in harmony with nature's ways. That people who have reached manhood and womanhood in a vigorous state of health do not maintain their health and efficiency to eighty years and upward is due generally to wrong ways in living. Many of the diseases proving fatal to men and women in the prime of life could have been prevented if these persons had been examined periodically by a competent physician, and had followed his advice as to diet, sleep, and exercise. Through the nervous system all activities of the body are directed and harmonized. Good health is impossible when the cells of the nervous system are exhausted. It is to be remembered, too, that the bodily energy is limited in quantity, and that what is expended in physical exercise is not avail- able for mental effort. Undue expenditures for either or both of these may rob the organs of the body of the energy necessary for their activities. On an average two hours a 31 32 GENERAL SCIENCE day or more of suitable exercise is a minimum requisite for attaining and maintaining a high state of bodily health and vigor. Continued neglect of exercise is likely to result in an unhealthful state of the body, and a diminished effi- ciency. Physical exercise should be as congenial to persons living a normal life as play is to children. Persons suf- fering from inability to sleep often find in manual labor, in long walks before going to bed, and in active sports, a degree of physical exhaustion that is conducive to sleep. To one who is at all thoughtful it is a marvel how lightly many people regard health, and the freedom and happiness that depend upon it. To be well born, and to have the con- ditions favorable for making the most of one's life, may be considered an inalienable right. To forfeit good health and well-being through lack of enlightenment, or of self control, does not lessen the irreparable loss sustained when strength and vigor have been thrown away, and life's opportunities that wait upon these have been wasted. Sickness usually causes more or less of pain, and life it- self is often put in jeopardy. A sick person in seeking to regain health must forego the usual activities of life, and be subject to losses through inability to earn and as expenditures incident to sickness. Sickness imposes more or less of a bur- den upon those who are called upon to care for the patient during his illness. Many times ailments supposed to have been " inherited" are but the results of the same manner of home life that caused impaired health in the parents. At any rate it is a great mistake ever to cease making intelli- gent efforts so to regulate one's manner of life as to overcome by hygienic living all defects and weaknesses whether in- herited or not. Disease and serious illness ought to be the exception rather than a common condition. In adults it is often an evidence of a failure to apply ordinary intelligence to the care of the HEALTH AND WELL-BEING 33. health. To strive to maintain the highest state ol health and efficiency in life is not only a wise course, but it is due recognition of an obligation to the interests of those in one's own family and in the community. Any excessive irritation of a nerve, whether by causes within the body or outside of it, results in pain. The mind locates the cause of the trouble in that part of the body where the particular nerve affected is distributed. Pain in any part of the body may be considered as nature's warning of something wrong there, and a call of distress from that part. Without the nerve to give this warning, the mind would have no knowledge of the danger. But so interlaced are the various nerve terminals, and so slowly is the power of interpreting sensations acquired, that oftentimes the one who is suffering may be entirely wrong as to the place and cause of the ailment. Even the trained and experienced physician is at times baffled in his attempts to diagnose a case correctly. Any intelligent treatment of one who is ill is out of question until the cause of the ailment is known. The skilled physician seeks to restore con- ditions in the body of the patient favorable for those bodily processes necessary to health. A watch, however perfect it may be in its workmanship, is of little value as a time-piece when any one of its train of wheels is improperly adjusted and does not move harmoni- ously with the others. No one part of the body can fail in performing its function (its particular work) without harm to the body as a whole. These failures may result from causes external to the body. A cinder "in the eye," a bit of food lodged in the larynx, an infected sliver under the finger nail, may cause derangements in the workings of the body as a machine even as a bit of dust when in the wheel-work of a watch. Medicines are given as an aid in restoring natural conditions in the body. In cases where 34 GENERAL SCIENCE the suffering is extreme remedies may be administered solely to ease pain and conserve the strength of the patient. In all muscular tissues the arteries, veins, and capillaries blende in a perfect network of blood vessels. Through them the blood must be kept moving in its round of circula- tion so that the tissues may be properly nourished. The blood is being continuously purified as it passes through the lungs and kidneys and other excretory organs. In the veins there is especial need to urge the blood on in order to lighten the -effort put forth by the heart in forcing along a sluggish cir- culation. The " blood pressure" which the heart must maintain to keep the flow of blood sufficiently rapid may overwork and weaken it. There is a constant menace of rupturing the walls of the arteries or other blood vessels under any abnormal pressure. In the veins the lining in places is so arranged in folds as to form pockets. These allow the venous blood to pass on toward the heart freely enough, but any backward flow is prevented as the veins are compressed by muscular con- tractions. Thus it is that muscular activities result in a better circulation. This brings more nourishment to the muscles themselves, and maintains a better state of the whole body. In a rush of blood to an affected part of the body to protect it from harm, and to repair any damage already done, there is occasionally a congested state of the blood vessels of that particular part. This is seen in the blood-shot appearance of the eyeball, and the feverish condition of FIG. 13. Pocket- like folds in the lining of veins serve as valves to prevent in part any backward flow of blood. (Bundy.) HEALTH AND WELL-BEING 35 the tissues about it, when a bit of dirt gets under the eyelid. One of the means commonly employed to determine whether the body as a whole is in a disturbed and unnatural state is by " taking the temperature" of the body. Any con- siderable departure of the body temperature from normal is cause for concern. Usually, if the temperature is approxi- mately normal, any illness experienced is likely to prove a temporary rather than a serious disturbance of the bodily functions. The small tube of the clinical (klin'-I-kal) thermometer used by physicians is very much narrowed and almost closed just above the bulb. The mercury in the bulb when warmed is crowded up through this narrow opening, and can be made to return only by jarring the tube. Since the mercury reading is always the highest point (temperature) reached, the instrument is one form of a maximum thermometer. SUMMARY Sickness and health are conditions of the body. To regain health after having been sick necessitates the restoration of the bodily condi- tions upon which health depends. Medicines are only an aid in bring- ing this about. The bodily processes alone can restore impaired health. Pain is nature's warning that something is wrong in the affected part of the body, and it may be considered a call not only of distress but for relief. In the body as in the care of machinery inattention to parts Out of adjustment may ruin the mechanism. The removal of the cause of an ailment constitutes the only hope of keeping the body well and fit to do its work. No intelligent treatment of one who is ill is possible without knowledge of the cause of the illness. Good health should be the rule, and sickness the exception, in well regulated living. Intelligent efforts to avoid whatever harms the body, and wisely to direct one's manner of living, is ordinarily the price that must be paid for good health and long life. There are times when the harm from use of medicines to deaden pain and give relief from suffering is less than the exhaustion from enduring the pain. It should be fully understood, however, that such relief is temporary, and is not in any sense a cure of the ailment. So 36 GENERAL SCIENCE dangerous are the drugs used for the relief of pain, and so ruinous their long continued use, that under no conditions are they to be employed save by direction of a physician. Exercise is indispensable to the maintenance of health and the development of the body. In order to be healthy all organs must be kept active. This is as true of the brain as of other parts of the body. Labor is the price for developing and maintaining a state of health. Work becomes a curse only when its demands on time and strength are excessive, and when one is a slave to it rather than its master. INFECTION Bacteriology, or the study of microscopic forms of life, is a new science. The story of its discoveries, and of the benefits which already have come to mankind through it, is as fascinating as fiction. Much of the present day knowledge of the effects of living organ'sms of microscopic size, whether one-celled animals known as protozoa or one- celled plants known as bacteria (see page 324), dates from the researches of Louis Pasteur (1822-1895). In 1857 the discovery was made by Pasteur (pas'-tur) that fermentation is due to the action of bacteria. In 1886 he was successful in his efforts to destroy the bacteria infest- ing the silk worms of France and Italy and threatening the destruction of the silk industry there. But it was when he turned his attention to the study of the causes of those diseases transmitted from one animal to another that the field of medical bacteriology was opened up. Some of his first experiments were with chickens affected by cholera, and later with cattle having splenic (splen'-ik) fever. He was able so to reduce the poisonous effects of a virus (poison) containing the germs of a disease that when it was administered to a healthy animal only a mild form of the disease resulted, and the animal became for a time immune to that disease. Here was the beginning of the use HEALTH AND WELL-BEING 37 of serums and antitoxins, and an explanation of the immunity from small pox by vaccination advocated by Dr. Edward Jenner (1749-1823) and practised more or less since 1796. FIG. 14. Louis Pasteur. (From Tower, Smith & Turlon.) Notable progress has been made in the prevention of typhoid by vaccination. It already seems probable that like small pox it is one of the dread diseases that will always be under control, and in time largely disappear. The vaccine material used contains dead typhoid germs that have been grown outside the body and then killed. Usually 38 GENERAL SCIENCE three injections are given ten days apart, and as a rule no interference with one's daily duties is experienced from the vaccination. Cases of typhoid are already rare occurrences in military camps because of enforced vaccination, and a strict observance of sanitary regulations. Discharges from the bowels and kidneys of typhoid patients should always be treated with a strong solution of "chloride of lime" for twenty minutes or more to destroy the germs before being thrown into cesspool or sewer. The danger of spreading the disease is thus greatly lessened. An understanding of the nature of many of the most terrible germ diseases that afflict humanity is one of the notable achievements of the years just at the close of the nineteenth century and at the beginning of the twentieth. There is reason to believe that the time may come when their ravages will cease to be the scourge of humanity. Preventive measures combined with medical skill and enforced sanitation have already accomplished much toward this end. Malaria, the sleeping sickness of Africa, and splenic fever in cattle are due to protozoa. The list attributed to bacteria includes typhoid, tuberculosis, pneumonia, tetanus (lockjaw), meningitis, influenza (grippe), diphtheria, leprosy, cholera, and bubonic plague. Measles, hydrophobia, scarlet fever, small pox, whooping-cough, and yellow fever are other infectious diseases not so positively classified. To this list may doubtless be added the dread diseases of cancer and infantile paralysis. Many of the so-called " children's diseases," such as measles, scarlet fever, and whooping-cough, are not only to be avoided but should be regarded as highly dangerous. This is chiefly on account of possible complications with other diseases, and because of a train of serious lifelong ailments that follow them, such as weakened eyes, affected HEALTH AND WELL-BEING 39 ears, and a condition of throat and lungs that makes them highly susceptible to germ diseases. The extended use of antiseptics to prevent infection of wounds, is associated with the name of one of Pasteur's pupils, Sir Joseph Lister (1827-1912), the famous English surgeon. The Pasteur Institute in Paris, and others of its kind elsewhere in the world, have been established for the purpose of giving treatment for rabies based on the dis- coveries of Pasteur concerning hydrophobia (1885). In< FIG. 15. Robert Koch. 1882 the German scientist Robert Koch (kok) discovered the germ of tuberculosis, and in 1883 the germ of Asiatic cholera. Von Behring, a German bacteriologist, discovered an antitoxin for diphtheria in 1892. It was during the occupation of Cuba by the forces of the United States (1900) that the part played in the spread of yellow fever by one kind of mosquito (Steg-o'-mi-a) was definitely established. By reason of the preventive measures taken, that scourge of the Tropics was soon almost com- 40 GENERAL SCIENCE pletely eliminated from the death lists of Havana. So marked has the control of germ diseases become in the pres- ent generation that during the building of the Panama Canal (completed in 1914) the health record there under American management was better than in many % cities of the United States. Under French management of the canal in the earlier years, and likewise when the Panama Railroad was built, the death lists numbered thousands 1 . Bacteria and protozoa that exist in or upon living plants or animals are known as parasites. Those that live upon dead or decaying organic matter are called saprophites (sap'ro-fits). As result of the growth and multiplication of these micro-organisms the tissues upon which they feed are broken down. In the human system the waste products of their activities seem to act as poisons (toxins), destroying the protoplasm of the cells. The expenditure of bodily energy on the part of living tissues in a battle against these destructive agencies, and in the elimination of the excessive wastes of the body, is indicated in a fevered state of the patient. The body after having become infected seems to have the power to produce products known as antitoxins. These either neutralize the effects of the toxins, or stop the mul- tiplication of the disease germs, or both. If these anti- toxins are produced rapidly enough after a person is infected, and in sufficient quantity, the patient recovers even from the most severe attacks; if not, he is likely to die. At times a patient surviving the cycle of life changes of the first of the germs has a " relapse," and a recurrence of the disease but with the original symptoms less pronounced. 1 The annual death rate of employees of the French company (1882-1890) was reported to be 231 per thousand. Under the later American control, when the agency of mosquitoes in yellow fever and malaria had become known, the death rate was reduced to 17 per thousand. There were no cases of yellow fever from 1906 to 1911. HEALTH AND WELL-BEING 41 Though at such times in a much weakened state by reason of the period of sickness that has preceded, the patient may recover. The poisonous waste products of bacteria in the putrefaction of foods are known as ptomaines (to-ma-inz). The efficacy of serums as prepared from the blood of animals known to have had an infectious disease seems to lie in the fact that such blood contains antitoxins of the disease. A person inoculated with this serum is thus fur- nished protection against toxins developed in his own system by the multiplication of germs. Serious illness or death is thus prevented during the time needed for his own body to produce the antitoxins in sufficient quantity. The toxins left in the blood by a disease often prove harmful to organs that have, not been infected, and death may result from it indirectly as in case of heart failure follow- ing pneumonia. Children often have diphtheria germs in the throat for some considerable time after their recovery from the disease. They may spread the diphtheria if allowed to return to school before a microscopic examination of discharges from the throat by a physician has shown it free of the germs. The diphtheria serum, first prepared by Von Behring, is from the blood of a horse. It contains the antitoxins of diphtheria developed in the animal during a prolonged period of infection. When diphtheria antitoxin is used at the first symptoms of the disease few deaths occur, while otherwise it is often fatal. The simple direction that the fingers and objects generally must not be put into the mouth should be insisted upon with children after the period of infancy till its observance has become habitual. The hands should always be washed before eating as a protection against infection as well as for personal cleanliness. Fruits such as apples, peaches, grapes, berries, etc.,, and all garden stuff that is eaten uncooked, such as 42 GENERAL SCIENCE celery and cabbage, should be washed until any danger of disease germs from the soil, the air, or from dust is unlikely. It seems wholly reasonable to believe the statements that more than one-half the sickness, and of the wretchedness caused by sickness, is produced by disease germs. Much of this terrible waste can be avoided by enlightened action on the part of individuals and communities. Many of the worst diseases that afflict mankind would speedily be brought FIG. 1 6. Danger of infection. Why not walk? under control, and perhaps would disappear, if the scattering of disease germs through carelessness and ignorance could be prevented. It is to be remembered always that disease germs come from sick people or sick animals, and that to pre- vent the dissemination of these germs is to wipe out the disease. Instruction in schools has an important part in this warfare upon disease. Attention to one's own health as result of studies in hygiene, and care given the health HEALTH AND WELL-BEING 43 conditions of a community through wise sanitary regula- tions, are matters of utmost importance. However, even the healthiest person has times of physical weariness, depres- sion, and weakness. At such times germs already within the body may get beyond control. Physicians are required by law to report at once to the Board of Health all cases of contagious disease. The place where any such disease exists is at once quarantined. A placard is posted giving warning of the disease, and forbidding persons to enter or leave the building. Germs of many diseases may be carried on the person or in the cloth- ing of those who have come in contact with an infected person. All members of a family where there is a contagious disease must be made either to remain at home or to keep away from home in order to lessen the likelihood of the spread of the disease. The quarantine period varies according to the length of time within which serious danger of infection exists. Before the quarantine of a room or building is removed it must be thoroughly disinfected under the direction of the Board of Health. It is the duty of every person faithfully to obey the quarantine regulations, however irksome these may seem, because of the need to safeguard the health and the lives of others. Ships coming into harbor are often held in quarantine when cases of contagious disease have occurred during the voyage, and neither people nor cargo allowed to land till properly disinfected. A quarantine is at times placed upon cattle and horses within certain districts where contagious diseases affecting them have become epidemic. The use of formalin (formaldehyde gas in solution) proves a satisfactory disinfectant for rooms and buildings. The furniture should be left in the room, and the bedding, rugs, and all clothing should be so spread out and hung up that GENERAL SCIENCE the disinfecting gas can get into every part of them. All cracks and openings of the room should be stopped gas tight. About a pint of the 40 per cent solution serves for a room of ordinary size, and the room should be kept tightly closed for twenty-four hours. Where sulphur is left burning in the closed room there is always more or less danger of fire, and the disinfection from sulphur alone is less satisfactory. It needs to be emphasized that most kinds of bacteria are harmless to man, and many kinds are of the greatest im- portance to his well-being. On the roots of such plants as peas, beans, clover, and alfalfa, certain bacteria thrive that have the power to abstract nitrogen from the atmosphere and convert it into compounds. These nitrogen compounds later serve as plant food, thus increasing the fertility of the soil. Other bacteria give to butter and cheese their appetizing By the multiplication of certain bac- teria in sewage it is rendered harmless. If it were not for the action of bacteria concerned in the decay of organic matter, the collection of refuse material in thickly settled sections would constitute an ever growing problem. Carbon taken from the carbon dioxide of the air, and nitrogen from soluble material as plant food in the soil, would thus, rapidly become accumulated in dead organic bodies, and be unavailable for plant growth. SUMMARY With the use of the term infection is associated the idea of disease transmitted by germs. These germs are microscopic one-celled plants known as bacteria, or are one-celled animals known as protozoa. In FIG. 17. The homes of "nitrogen - fi xi ng" bacteria. (Conn.) tastes and odors. HEALTH AND WELL-BEING 45 both cases they are parasites, and they are destructive of the tissues in which they lodge and multiply. As the germs live and multiply they also produce substances known as toxins which have the effect of poisons upon the body as a whole. The human body when infected seems to have the power of forming other substances known as antitoxins which counteract the effects of the toxins. If these are in sufficient quantity in the body they lessen the severity of the illness or wholly prevent its development. Blood withdrawn from an animal which has had an infectious dis- ease, such as diphtheria, is supposed to contain in its watery part, or serum, antitoxins developed in the animal. This serum introduced into the blood of a human being counteracts the poisonous effects of the germ life without waiting for the slow development of antitoxins in the body of the one who is ill. Hope of controlling infectious diseases, if not of their eradication, lies in the prevention of the scattering of the germs developed in in- fected persons. This involves the isolation by quarantine or otherwise of any one sick with an infectious disease. It is equally important that all discharges from the body of the patient, and all infected clothing and other articles, shall be disinfected thoroughly by use of chemicals, by sterilization, or by fumigation. The discharges from bowels and kid- neys especially should be treated with a strong solution of hypochlorite ("chloride") of lime before being thrown into sewer or cesspool. Danger of infection through foodstuffs is almost wholly removed by thorough cooking. In the laundry clothing should be boiled for fifteen or twenty minutes. Raw vegetables and fruits, and milk not pasteur- ized, are always possible means of infection. One argument for the use of hot drinks rather than cold water lies in the use of water that has been boiled. SANITATION Providing the food -supply for a family to-day in the United States is a very different matter from what it was a half century ago. Then the vegetables, fruits, and meats, together with the products of poultry yard and dairy, were home products for home consumption, or were bought direct from the producer. Home-grown animals were slaughtered at home. Some of the meat was used fresh, 4 6 GENERAL SCIENCE and other portions cured at home for later use by salting, pickling, smoking, and drying. Cellars and caves were piled with potatoes and other vegetables, together with apples and other orchard products. The rafters were hung with dried fruits, while pickles and preserves added variety in diet. Fresh eggs, with plenty of milk and poultry always at hand, made necessary but few food supplies from town. FIG. 1 8. Insanitary conditions here. Not infrequently there was on hand enough food to last through the months of a winter season. To-day the grocer, butcher, baker, and milkman furnish the family supplies as needed day by day. Who selects and prepares these foodstuffs, and whether or not it rs done under sanitary conditions, is unknown to the purchaser. It thus becomes necessary as a matter of self-protection to enact stringent laws governing the preparation and the quality of the food supplies put on the market. Provision HEALTH AND WELL-BEING 47 must be made for food inspectors as public officials to see to it that these laws and their penalties are enforced. An enlightened citizenship is necessary that these officials may have an active support and a hearty co-operation in law enforcement. Those desirous of carrying on business in an honest and law-abiding manner should not be compelled to meet the competition of those who by misbranding, adul- teration, short weights, and other fraudulent practices seek unfair advantage at the expense of purchasers. Preservatives are sometimes used in foodstuffs to prevent chemical changes caused by bacteria. Milk can then be kept a longer time from becoming sour, and meat from becoming tainted. Some preservatives are prohibited by law because it is believed they interfere with the chemical changes involved in the digestion of the preserved foods, or because they act injuriously upon the tissues of the body. Small amounts of preservatives are at times used in foods put up in cans or other sealed containers when the food material as prepared for market is of an unwholesome or inferior character. Bacteria multiply in summer much more rapidly than in winter. Fish must be kept continuously on ice in summer since it decays rapidly and soon becomes dangerous for use. Meat of all kinds, including fish, and poultry, and "shell- fish," soon spoils when removed from cold storage or from cans. This is due to the rapid multiplication of bacteria in it. The refreezing of melted ice cream in which there are any poisonous secretions known as ptomaines, developed from bacteria while the cream was unfrozen, does not free it from its dangerous character however appetizing it is made to appear by use of flavors and coloring material. Poisonous products from bacteria increase rapidly in milk in summer time, causing wide spread illness and death among babies. Fresh milk and other fresh foods contain no pto- 48 GENERAL SCIENCE maines. Bacteria develop slowly or not at all at a low tem- perature, or in foods preserved in sugar, vinegar, salt, or by use of smoke. Meats and fruit products, such as catsup and sausage, left exposed for sale day after day without spoil- ing presumably contain chemicals that prevent multiplica- tion of bacteria. These chemicals likewise make the foods kss digestible if not positively harmful. It is a part of the varied duties of Food Inspectors to see that no use is made of impure and unwholesome material in the preparation of foodstuffs, however attractive these may PIG. 19. Typhoid fever germs highly magnified, and much more in 2 than in i. be made in appearance and price. The use of any cheaper quality of a substance, or of a cheaper substitute in the preparation of a staple foodstuff, constitutes an adulteration and is prohibited. Any dishonesty in sale of articles under a misleading brand or label is in violation of law. The general principle involved is that while the purchaser has the right to buy whatever he pleases, providing it is not an open menace to health, he needs protection in getting what he pays for so far as its nature, quality, and quantity are concerned. The various States by laws of their own, and in co-operation with the national government through its interstate commerce legislation, seek to prevent wholesale impairment of the health of the nation through its food supply. Upon a rigid enforcement of pure food legislation, and upon the skill of those who make chemical analyses of HEALTH AND WELL-BEING 49 foodstuffs sold in the open market, the public must depend for a large measure of its protection against loss in efficiency and shortened lives due to unfit substances in the foods purchased. As a bacteriologist the sanitary expert must be able to recognize and identify any disease germs present in the water, milk, and food supply of a community. To qualify as an expert in any one science usually requires college and university training. But so simple are the funda- mentals of sanitation that the sciences of the high school give a good understanding of the conditions for personal and community health, and how these may be conserved. The relationships and applications of hygiene and sanitation are as wide and as far reaching as are human activities and inter- ests. No one in a family circle can suffer sickness or disease without in some measure affecting the interests of all its members. The health and well-being of every individual is a matter of concern for the community and the State. Directly or indirectly those now in the public schools need to be concerned with the safe-guarding of the health of those who work in factory, shop, mill, store, and office. In later years nearly every boy and girl now in school, either as em- ployers of labor or as employees, will have a personal as well as an industrial and social interest in the sanitary condi- tions under which the indoors work of the world is being carried on. Even in school days the health of the parents, whose earnings make possible the maintenance of homes and the welfare of the family, are matters of concern to all boys and girls. In towns having a good supply of city water, with modern plumbing conditions, there is absolutely no excuse for any lack in shops, mills, factories, and public schools of sanitary drinking fountains, and of well-kept toilet rooms. To keep the floors, walls, and fixtures of toilet rooms neat and clean requires co-operation with the care-takers of the buildings. SO GENERAL SCIENCE Misuse of these rooms and of their furnishings by any one is evidence of unfitness to associate with those whose ways are decent and considerate. The extended use of ice in summer time, especially when put into water or other drinks to cool them, involves risks to health from two causes. The chilling effect upon the digestive tract, due to any reduction in temperature much FIG. 20. Sanitary drinking fountain. below 99 F. not only seriously affects the distribution of the blood supply of the body but it impairs the powers of secret- ing the digestive fluids. Then, too, there is the ever present danger of infection from the ice. Whether artificial or natural, it may have become contaminated either in its storage or in its distribution to the consumer. Complete protection from infection demands that ice shall never be put into drinks of any kind. HEALTH AND WELL-BEING 51 SUMMARY Sanitary regulations and pure food laws in late years have become more and more matters of importance. There is need of the strictest supervision over all sources of the food supply, and over the manner of preparation and sale of foods. The rigid enforcement of all regulations affecting public health has become imperative. The food supply of a family to-day is very largely from sources outside the home, and it has been handled by persons unknown. The purchaser cannot be expected to know how it has been prepared and cared for. Wholly unfit materials may have been put up in an attrac- tive form for sale; chemicals destructive of health may have been used; and substances of inferior quality may have been introduced as adulterants. In order to preserve foods for long periods in condition fit for use, they are salted, smoked, preserved in sugar, or kept at or below freezing temperature. All these conditions hinder the multiplication of the germs that cause decay in organic matter. Where foodstuffs are canned the materials are sterilized at a high temperature, and are then sealed air-tight in cans to prevent the entrance of germs. Ice cream that has been allowed to melt may be refrozen, but the refreezing does not destroy products of decay in it. Serious and even fatal results as ptomaine posioning may follow the use of foods con- taining the products of decay. Instruction in the schools is concerned with whatever affects the public health as well as that of individuals. It should contribute toward an enlightened citizenship that will enforce laws and regula- tions for the welfare of community life. Exercises 1. What constitutes being temperate in one's living? 2. Distinguish between bacteria and other "microbes." 3. In what ways does the multiplying of bacteria (or protozoa) within a person's body cause sickness, and bring about a diseased state? 4. Account for the certain "periods" through which different diseases run? What may be the explanation of a relapse, or a recurrence of the same ailment with all the original symptoms? 6. Give general definitions of (a) virus; (b) serum; (c) vaccination; (d) inoculation. 6. What is it to be immune to any disease? How is immunity explained? 7. What is an antitoxin? Explain its remedial effects. 52 GENERAL SCIENCE 8. Distinguish between (a) infectious and contagious diseases; (b] antiseptic treatments and sterilization. 9. Wherein lies the great worth of formalin as a disinfectant? 10. Of the various disinfectants whose solutions are used, which is perhaps the most generally satisfactory for treatment of waste material from sick rooms? 11. What is a wise course in the matter (a) of wearing other people's clothing; (6) of using public drinking cups and towels? 12. What possible dangers are there in the use of public plunge baths and swimming pools? 13. What sanitary purpose is served by cooking all meats? In the canning of perishable foodstuffs, upon what does their preservation depend? 14. How is a case of any contagious disease to be accounted for when so far as known the patient has not been "exposed?" 16. About how many years is it since Pasteur's use of the microscope laid the foundations of bacteriology? Tell something of his early discoveries. Mention other men whose researches have made notable advances in this field of science. 16. What is a necessary course to pursue with fruits and vegetables from the market which are to be served at table without being cooked? Name several fruits and vegetables eaten uncooked. 17. Under what conditions might ailments ordinarily not quarantined, such as whooping-cough, prove serious and even fatal? 18. What are the usual restrictions placed upon people when quarantined? 19. Of vaccination for the prevention of typhoid fever tell (a) how it. is done; (b) what the vaccine is. THE WATER SUPPLY AND HEALTH An attempt to list the various uses of water, and to state the part that it plays in the economy of nature and the wel- fare of men, proves highly instructive. The extent of its uses is scarcely more striking than is the abundance of the supply needed for these uses. The round of changes in place and form undergone by water in the economy of nature is one of the marvels of the natural world. In cities provision must be made to furnish water for drinking purposes, for cooking foods, for use as steam power in mills, shops, and factories, and for heating dwellings and other buildings. An enormous supply is necessary for the disposal of sewage, for fire protection, for laundry and bathroom, for lawn and HEALTH AND WELL-BEING 53 garden, and as ice for refrigeration. Large quantities of water are necessary in factories, gas works, dye houses, and other industries. It is indispensable for the maintenance of all plant and animal life, and for human existence. New York City gets a portion of the enormous supply needed by its population and for its varied industries from the watershed of the Catskill Mountains ninety miles away. The expenditures of this one city alone for its supply and distributing systems represents outlays of hundreds of FIG. 21. Contamination of well water. (U. S. Public Health Service.) millions of dollars. Transportation by water has in all ages been one of the chief agencies in the promotion of manufac- tures, of commerce, and of .civilization itself. After surface waters from rainfall and melting snows have soaked down into the earth's crust any considerable number of feet, these waters commonly may be considered pure by reason of filtration and aeration. Slow oxidation will have freed the water of organic matter, and the material in solu- tion will be harmless minerals. Drainage from barnyards, cesspools, privies, and house drains may, however, find its 54 GENERAL SCIENCE way into the waters that collect in. surf ace wells. This sew- age is not only poisonous to the system, but it may carry into the well water disease germs such as typhoid. In towns and cities where soils are laden with organic waste material the use of water from surface wells is prohibited. Unless one knows the conditions surrounding a surface well, and some- thing of the strata into which it was dug, it is always wise to regard with suspicion any water taken from it for drink or for use in preparing foods. Surface waters sometimes find their way down between layers of rock that are sep- arated by a porous stratum where they collect under the pressure of their own ac- cumulation. Boring down into this water-filled layer may result in a rise of these underground waters to or above the surface of the ground. Such- waters are usually free of organic matter and disease germs by natural filtration and aeration, but may hold much mineral matter in solution. Where rain water is caught and stored in cisterns, in spite of all precautions more or less of dust and of decaying vegetable matter will be washed from the roofs into the cisterns. The water may acquire a disagreeable odor and taste from the decay of the organic matter present, and be- come more or less dangerous as a drink. This organic FIG. 22. Use of chain pumps to aerate cistern water. The inverted metal cups carry air down into the water and liberate it as the cups fill with water at the bottom. HEALTH AND WELL-BEING 55 matter may be destroyed by a sufficient supply of oxygen dissolved in the water. This aeration is very satisfactorily accomplished by use of a pump that carries water up on one side of an endless chain in a series of small metal cups FIG. 23. An air-pressure water system and plumbing for a house where there is no city water supply. The pumping may be done by hand, by a gaso- line engine, or by a windmill. attached to the chain. This chain runs over two wheels, one at the surface and one held suspended down in the water near the bottom of the cistern. As these cups are inverted when they pass down into the water, air is taken down and 56 GENERAL SCIENCE liberated within the cistern waters every time the pump is used. There is always danger that surface waters and sewage may seep into a cistern through cracks in its upper walls. These walls should always be so laid as to prevent leakage into the cistern as well as leakage out from it. This can be accomplished by use of non-porous brick laid in cement for the walls, and by having the inner side of the walls plastered with cement. The aeration of the waters of city systems is accomplished in various ways. In cases where water is pumped directly into the mains enough air may enter with the water to keep it thoroughly aerated. In storage reservoirs arranged on different levels above one another, the water is allowed to flow from the higher to the lower levels in long thin sheets, falling with more or less of spray into the lower reservoirs. Very often, too, provision is made for filtering these waters through layers of sand and gravel. In dwellings where no city water supply is available, water from cisterns or wells is sometimes forced into large steel cylinders partly filled with air. By reason of the pressure of the compressed air, the water flows through pipes to all parts of the house so long as the air pressure is maintained by frequent pumpings. SUMMARY The provision of an abundance of pure water for household and general uses is indispensable to the welfare of people whether living in towns or in rural districts. Sanitary conditions require an ample supply of water for the removal as sewage of the waste matter of towns and cities. The large use of water for fire protection, for street clean- ing, for homes, for public laundries, for mills and factories and various other industrial plants, makes necessary large outlays for the construc- tion and maintenance of water systems. The utmost vigilance is at all times necessary to safeguard the water HEALTH AND WELL-BEING 57 supply on the farm and in the city. Disease germs in the water may cause widespread sickness and death. Water from surface wells and streams is always subject to suspicion when not safeguarded with the greatest care. The source of the water supply for different cities, and the manner of its purification, varies according to local conditions. In some cases it is pumped from deep wells into the water mains; in other cases it is taken from rivers or lakes and stored in reservoirs where it is freed from any sediment before being allowed to flow into the distributing pipes. Sometimes certain chemicals are introduced to hasten the settling of suspended matter, and in other cases chemicals are used to free the water of organic matter and disease germs if any be present. Some definite knowledge of the water system of one's own -city is a requisite for any sufficient understanding of conditions affecting the community welfare. Apart from the presence of disease germs, the existence in drinking water of decaying organic matter, whether in a finely divided state or in solution, is a source of sickness. Oxidation is the readiest means of freeing water of organic matter, whether of animal or vegetable nature, and whether from sewage or from decaying vegetation. Cistern water may be kept aerated by the use of a chain pump. Running water in streams is likely to have become purified by its exposure to the air, especially where its volume is not too large and where its current is more or less broken. The stored water of reser- voirs may be aerated by forcing air through it from pipes laid in the bottom of the reservoir, or by the use of fountains whose spray of water falls back into the reservoir. Where water is pumped into the water mains, sufficient air for its aeration may be made to enter along with the water. GENERAL HEALTH PROBLEMS The life history of flies and mosquitoes possesses great interest aside from the possibility of their becoming carriers of disease germs. A study of the structure and transforma- tions of all insect life, and of the relations of insects to plants and to mankind, is a field of science of unsurpassed interest. Insects are of utmost economic importance to man, affecting his health, comfort, and prosperity in innumerable ways. 58 GENERAL SCIENCE The honeybee and the silk worm contribute to his well-being. But in spite of their marvelous beauty of form and coloring, and all the wonder which their structure and transformations and adaptability to changing conditions may call forth, insects are generally to be regarded as pests. They are a destructive agency against which ceaseless warfare is to be waged. There are more known species (various kinds) of insects than there are species of all other animals combined. So great is the number of insects that they are said to com- prise three-fourths of the animal kingdom. Any good text on animal biology will furnish information of greatest worth concerning insects. We do not need to be scientists, however, to acquire sufficient knowledge of this group of animal life to understand how our health and comfort are affected by them. In a general way the bodies of insects may be described as consisting of head, thorax, and abdomen. On the head are a pair of relatively large eyes, and two antennae or "feelers." Attached to the thorax are two pairs of wings above, and three pairs of jointed legs below. The abdomen is made up of a series of rings or segments. Moths, bees, flies, butter- flies, or grasshoppers may be chosen for making studies of insects. A pocket lens is a great aid in making these studies. The feet and body of the common house fly as seen under a magnifying glass appear hairy. A sticky secretion on the feet of the fly enables it to walk on smooth surfaces, and in all manner of positions. As the common house fly revels in filth of all kinds it is a menace to health everywhere it goes. There is always the possibility of germs of typhoid, tuber- culosis, or dysentery being left by flies on foodstuffs, and on the dishes used in kitchen and dining room. The female fly may lay one hundred eggs or more at a time, and under favorable conditions these may hatch within a day. The larva (grubs, or maggots) grow rapidly, especially if lodged HEALTH AND WELL-BEING 59 in a pile of horse manure, and in about five days change to the pupa stage. In another week the full grown flies emerge, and the cycle of changes is repeated. Thus it is that in about two weeks one hundred eggs may become .one hundred flies. As each female may lay four lots of eggs in a season it is possible for a single fly to be multiplied into millions between spring and fall. PIG. 24. The house fly. Control of the menace from flies lies in the fact that rela- tively few flies live through cold winter seasons, and that they do not go far away from their breeding places. The survi- vors in the spring may be trapped and the conditions for breeding may be made unfavorable throughout the season. Piles^of refuse about stables, and of decaying organic matter anywhere, are favorite breeding places. Any successful 6o GENERAL SCIENCE warfare upon flies requires preventive measures. From the earliest springtime, large outdoor flytraps should be kept about garbage cans, in stables, and near the outer doors of kitchens or wherever else food is being prepared or served. The eggs of the common mosquito are found floating in stagnant water. Under favorable conditions these may hatch W FIG. 25. Life history of the mosquito. i, eggs; 2, larva; 3, pupa; 4, the common mosquito (Culex). WW, water level below which larva and pupa almost wholly float. This makes possible" their suffocation with a thin layer of crude petroleum spread over the water surface. within one day. The larvae (known as wrigglers) after about a week of rapid growth enter a pupa stage. This state continues but a few days when the change to a fully developed mosquito occurs. In waters stocked with fish, these wrigglers are devoured.in large numbers. Where water surfaces of stagnant pools in marshes are covered with a HEALTH AND WELL-BEING 61 thin film of crude petroleum, the mosquito larvae are smothered, and the numbers of mosquitoes in any locality during a season is materially lessened. While the common mosquito culex is a great annoyance, the malarial mosquito anopheles (a-noi'-e-les) is a direct menace to health. (See page 39.) The discovery of the germ of malaria in 1880, and of the existence of malarial germs within the body of the mosquito as its host, with , reasons for the belief that without the mosquito as an inter- mediary there would be no transmission of malaria from per- son to person, forms a wonderfully interesting story. When a malarial germ once finds entrance into the blood of a person, it lives and subdivides within some red blood corpuscle. After a period of a few days the corpuscle is broken down, and the multiplied germs are set free in the blood to enter other red corpuscles where further multiplication occurs. The characteristic chill of malaria usually follows these periodic liberations of the malarial germs in the blood. One of the problems of a city administration is the removal of garbage economically and efficiently. The value of the waste in the garbage of a large city, including various metals, old rubber, cloth, glass, and grease, aggregates great sums annually. Destruction of garbage by fire removes the menace to health from any disease germs present in it. The sewage of a great city represents an enormous loss annually in fertilizer for soils. Sanitary conditions, however, and the cost of transportation of this material to places where it could be used, make any prevention of this economic waste largely out of question. Rats have long been regarded as a pest, but have been tolerated. The waste caused every year by their depreda- tions on farms, in warehouses, in dwellings, on shipboard and elsewhere is enormous. Since their agency in the spread of the dread bubonic plague has been established, active 62 GENERAL SCIENCE measures for their extermination have followed. Rats may become infected by bites of fleas that have bitten plague- stricken patients. Wherever these rats go the disease germs may in turn be transmitted from the rats to persons by agency of fleas. In these days of cement construction there is no excuse for rat-haunted dwellings and storehouses. Hunting and destroying rats on an extensive scale is expensive. Their extermination can be accomplished in time by imposing appropriate penalties for harboring rats upon owners of ships and buildings. It should be kept in mind that rats and mice remain only where food is available for them, and that to properly protect foodstuffs at house, barn, store, and warehouse from depredations of rats is to lessen their numbers if not entirely to be rid of them. SUMMARY In agriculture the destruction wrought by insects, especially while in the larva or "worm" stage, is almost incalculable. Insects are not only a pest so far as man's comfort goes, but they are a menace to his health and to life itself. Insects constitute the most numerous division of the animal kingdom. Between the egg when hatched, and the fully developed insect that in turn lays eggs for another generation, there are variations in the length of time required by different species to complete the "cycle." There are differences in the succession of changes that occur. How- ever, from the eggs come the larvae variously known as "worms," "mag- gots/* "grubs," or "caterpillars;" then comes the pupa or "chrysalis" stage, followed by that of the grown insect. Insects in general are characterized by having the three parts head, thorax, and abdomen. The eyes and antennae are parts of the head; to the thorax are attached the legs and wings; and the abdomen is made up of connected ring-like parts. While there are many kinds of flies, some of which are tormenters of both men and animals, the common house fly as a carrier of filth and disease germs should be exterminated as a sanitary measure. The discovery of the part played by some kinds of mosquitoes in the HEALTH AND WELL-BEING 63 spread of certain diseases, and the logical application of this knowledge to other health conditions, constitutes one of the brightest pages in the history of preventive medicine. In the increased use of cement for building purposes lies one of the chief aids in the warfare upon rats and mice. Without access to food supplies, starvation will keep their numbers down. They are a menace to health as carriers of disease, and their destruction of foodstuffs and other property necessitates their extermination. Freedom from vermin of all kinds is an indispensable sanitary measure. FIG. 26. A breeding place for house flies. Exercises 1. Name various ways in which the waters of wells near dwellings and farm buildings are likely to become contaminated. 2. How may surface drainage into wells be prevented? 3. Describe the action of "chain pumps" as means for the aeration of cistern waters. 4. Why are cisterns as sources of water for household uses in large towns and cities quite out of question? 5. How may the stored waters of large reservoirs in city water systems be aerated? 64 GENERAL SCIENCE 6. How may the presence of disease germs in any sample of water be determined? 7. Why are such vigorous campaigns waged to exterminate flies and mosquitoes? 8. Why is it that the "scale" forming on the inside of boilers is so seriously objectionable? 9. Of what service is water in the nutrition of the body? Discuss how it is that the abundant use of water internally contributes to health and length of life. 10. In a general way what duties and responsibilities rest upon every in- dividual in any community as to matters of public health? 11. In what perfectly honest way may it be possible for a dealer in food- stuffs to be able to sell at lower prices than some of his competitors? Name some dishonest forms of competition in the preparation and sale of foodstuffs. LIFE, GROWTH, REST, AND RECREATION Under the microscope it is found that both plant and animal tissues are made up of cells. While there is a wide variation among cells in form and arrangement, and in other respects, every living cell consists essentially of a more or less fluid content known as protoplasm. This possesses life, and it has the powers of growth and of subdivision. Food for plants and animals includes all the material required to build new cell walls, to nourish the protoplasm, and to furnish the energy required in keeping the organs of the body active. The outer portions of the hair, skin, and nails, as well as those growths known as corns, warts, and callouses, consist largely of layers of dead cells. These are pushed outward and away from the living growing tissues underneath. A lessened blood supply to any such part of the body where unnatural cell growth is taking place may hinder and in time stop the undesirable growth. In trees the greater part of the wood structure consists of cells largely or wholly destitute of life. So long as these are enveloped by living tissue, however, decay of the wood does HEALTH AND WELL-BEING 65 not occur. There is an increase in the size of the tree by reason of the added annual wood formation. In animal life, on the other hand, prompt removal from the body of the dead cells of the tissue by oxidation or otherwise is necessary for the maintenance of health. Irritation of any organ, or of any part of the body, causing an excessive blood supply there and a congestion of its blood vessels, stimulates excessive secretions and a cell-building that is likely to be unnatural in character. The high tem- perature of the inflamed region is likely to affect unfavorably the protoplasm of the cells. With the system unable to rid itself rapidly enough of waste matter, illness follows. Medi- cines may be required both to remove the cause and to stimu- late the organs of the body to a more prompt removal of the waste material. Sustained mental activity of a high order requires a well- balanced physical development. All organs of the body, including the brain and nervous system, must be in a healthy and well-nourished state. Apparent exceptions to this rule may be explained (though not accounted for) by saying that mental activity occurs in spite of bodily infirmities, and that it is always limited more or less by them. It may be con- sidered true generally that health and efficiency are through- out life directly dependent upon wisely ordered bodily ac- tivities. The brain and nervous system can be kept in tone and vigor only through sufficient and suitable exercise of the whole muscular system. On the other hand, the mind is largely independent of abnormal muscular development and of excessive bodily strength. A " sound mind in a sound body" has no necessary reference to physical prowess and athletic training. Any cells of the body if kept inactive become less vigorous, and finally die as a result of disuse. The muscles unused become weak and flabby. Activity in all tissues is essential 66 GENERAL SCIENCE to their healthful state, and this is as true of the brain and nervous system as of other parts of the body. The person who maintains many interests in life, and a variety of activities both mental and manual, is not only likely to lengthen life thereby but to add to it many years of efficiency and of enjoyment in living. Rest is essential for both body and mind that their activi- ties may be continued. The human body as a machine at work does not provide energy rapidly enough, nor make FIG. 27. Gardening is good exercise. tissues fast enough, to keep up with the waste. Unlike ordinary machines it is rebuilding its parts as it goes along. This requires time, and favorable conditions, and a suitable food supply. Sleep is needful to keep the body vigorous and in a healthy state. Those hours that are spent in sound refreshing sleep are not wasted. Sleep to be refreshing should be free from disturbances and interruptions, and from the ill-effects of an intemperate diet. Eight hours per day is enough sleep for people generally. HEALTH AND WELL-BEING 67 But excessive labor of any kind, and the wear incident to it, may require a correspondingly longer period to rebuild tissues and restore the energy of the body. Children during the years of their growth require more sleep than adults. FIG. 28. School gardens. Sitting up late at night for study as practised by students in school is not generally advisable. Social indulgencies that carry festivities late into the night are to be wholly avoided. Physical weariness when not excessive is conducive to sleep, 68 . GENERAL SCIENCE and oftentimes sleeplessness is a direct result of insufficient physical exercise. The human body cannot manufacture something out of nothing. A healthy cell growth, and a vigorous protoplasm, is a natural result of a temperate and simple manner of life. Intemperance in matters of food, sleep, drink, occupations, and amusements dissipates the energies, and proves destruc- tive to health and to life itself. When machinery of the ordinary kind wears out or breaks down, it can be thrown on the scrap heap, and new machines put in its place. But it is difficult to conceive that any sane person will deliberately choose a course in life that must inevitably lead to his breakdown in body and mind. Ignor- ance of violations of the laws of well-being, and of the results of any departure from the ways of right living, does not change those results. Enlightenment as to the conditions for attaining and maintaining physical and mental vigor con- stitutes one of the most important parts of school instruction. Recreation seeks that restoration of body and mind which makes possible the best efforts of both. There is little need to remain long in doubt whether any particular course in life is recreation, or is instead a dissipation of one's energy and powers. While in amusements there is oftentimes no thought other than of pleasure, rest and invigoration should always result from them. Here as elsewhere, the dividing line between recreation and dissipation may be quickly discerned by one who is thoughtful of his own well-being and of the welfare of others. It is a law of human life that any right use of time and strength, and of the powers of body and of mind, brings increase in ability to do ; their disuse or misuse renders one less capable. It is indispensable to health and happiness that one avoid all those pleasures that overtax the bodily energy or tend toward disease and immorality of any kind. HEALTH AND WELL-BEING 69 The games and sports of childhood and youth furnish much of the exercise essential to the development of healthy and vigorous bodies. They make possible more enjoyment in living, and greater ability to do well the labors that devolve upon one throughout life. In rural communities a wide range of wholesome occupations and out-of-door sports is always possible; in towns and cities these opportunities are more or less restricted. So important is play considered by those who have at heart the interests of children and of society at large that special effort is made in cities to provide properly supervised sports and physical training for both boys and girls. Aside from any outlays involved, the nature of one's em- ployment in life should dictate very largely the forms of recreation chosen. In a general way the best results are attained from those amusements, recreations, and enter- tainments in which there is the most of enjoyment and of restfulness. The benefits from being an on-looker at games and plays is very generally far short of what might result from actual participation in them. This is especially the case in active out-of-doors sports and occupations. No one could reasonably think of being nourished by food eaten by another, or of growing intellectually as result of getting some one else to do his thinking for him. It is a great pity for people to deceive themselves into being content with not taking part in sports and other forms of physical exercises. Any excessive amount of time or attention given over to amusements or to sleep constitutes intemperance in living, even as does excessive labor of muscles or brain, or over- indulgence in eating and drinking. It is the experience of the human race that besides the natural rest periods given over to sleep, the welfare of individuals throughout life requires an additional one day out of every seven, approximately if not literally, in which 70 GENERAL SCIENCE the usual routine of life is set aside 1 . This time should be so used as to rest the worker, and to elevate his intellectual and moral life. Sports and games are forms of amusement in which there should be a combination of suitable physical exercise and a rational mental activity, with sometimes one and sometimes the other dominating. The greatest enjoyment and largest FIG. 29. A restful scene. benefit comes from out-of-doors sports, and from games played for the fun there is in them rather than for commer- cialized or competitive ends. To permit one's self to become intensely wrought up, and to experience any long sustained excitement in witnessing professional games or plays presented upon the stage, may be exhausting in its results rather than restful and recupera- 1 In this connection it is to be observed that the "Ten Commandments" delivered to the Israelites by Moses for their welfare as individuals, and for their existence as a nation, laid stress upon the requirement "Six days shall thou labor" as well as upon setting apart the seventh day as a day of rest and religious observances. HEALTH AND WELL-BEING 71 tive. In all cases where participation in games and sports is impossible, and where they are promoted as money- making schemes, it is always well to consider carefully whether indulgence in them is not likely to become dissipa- tion rather than recreation. It does not require any large amount of observation of effects to determine whether or not any particular form of amusement benefits or harms one physically, and whether it interferes with the discharge of one's duties; whether it refines and uplifts one's ideals of life, or tends to brutalize and degrade them. Nor does it require any large amount of ability to plan and accomplish much in the way of providing pleasurable and restful occupations about the home, and in connection with home life. SUMMARY The human body is a structure built up of units known as cells. The same is true of other animals, and of plants. These cells are of many forms, and they have widely different uses. All living cells essentially consist of a semi-fluid content known as protoplasm. It is the "living matter" of the body. Growth in the body is the result of a subdivision of the cells due to activities of the protoplasm. 1 The cells get nourishment from the watery fluid by which they are surrounded. This lymph is much like the watery part of the blood. Into it the cells discharge their waste, and this sooner or later gets into the blood. Once inside the blood vessels, it is carried in the round 1 Attention is called here to a theory of biological science which is funda- mental in its importance, viz., that the "life" in every living form has been transmitted from some earlier existing parent life. Each successive genera- tion of plants and of animals has life because of cell protoplasm derived from a parent plant or animal. In other words, there is no such thing as "spon- taneous generation" of life, and no creation of life energy any more than with other forms of energy. This implies that in a remote past there must have been a time when "In the beginning" there was a creation of life making possible the continuity with which the study of biological science makes us acquainted. Concerning any such time and creative act science, of course, teaches nothing. 72 GENERAL SCIENCE of circulation to the special organs by which it is eliminated from the body. The great value to health of suitable exercise lies in an increased activity of the cells, a larger supply of nourishment brought to them, and a more complete riddance of the waste of the body from the cells and tissues. The brain as organ of the mind requires nourishment, exercise, and freedom from exhaustive labors for its growth and activities even as other parts of the body. The need of rest for the human body, including those periods of sleep when complete relaxation should occur, results from the fact that the human body does not rebuild its cells rapidly enough, nor provide energy sufficiently fast, to make good the waste of the body in its hours of activity. Recreations may be considered as including all those occupations where the general results are restful. Recreation ranges in character from what is done solely as amusement to what is merely a change in form of labor. This latter is restful because it calls into use activities of the body before unused, thus freeing those parts which have become wearied. STIMULANTS AND NARCOTICS There is a certain rate at which an engine or dynamo does its best work, and where there is the least wear. Both its efficiency as a machine and its length of life as a working agent require that it be run at its normal capacity. To overload a dynamo or a steam engine, or to speed either beyond a normal rate, means its destruction. The human body in spite of its recuperative powers suffers from the wear and waste of an unnatural strain put upon it in the use of alcoholic drinks, and sooner or later breaks down. The vital organs are affected seriously, and it is upon them that length of life and vigor of health largely depends. One may live long and be an active agent in the affairs of life after the system is incapacitated for hard muscular labor; but there is always a need for vigorous heart action, active nutritive processes, and healthy action of kidneys and lungs. The HEALTH AND WELL-BEING 73 remedy at any time for lack of vigor and strength, whether of body or mind, is not some stimulant to further use up the scant store of energy, but hygienic living in order that the physical conditions be such as to provide the needed strength. Only workmen with clear minds, skillful hands, and steady nerves are wanted in the railway service, in the great indus- tries, and in all positions of trust and responsibility. Dissipa- tion of any sort shatters the nerves, beclouds the brain, and unfits for effective service. Such workers are discriminated against in the affairs of the world everywhere and cannot hope to secure and retain its most desirable positions. The continued use of small amounts of alcoholic liquors impairs the health, reduces the recuperative powers of the body in cases of illness, and makes one more liable to in- fectious diseases. Insurance companies often refuse to take life risks of even moderate drinkers because of the higher death rate among them. The debauching effects of an excessive use of alcoholic drinks is a matter of common observation; and the use of alcohol as a beverage is a menace to human life and social welfare. The testimony of texts on human biology con- cerning its destructive results upon the nerve centers that are concerned in the higher intellectual processes is scarcely required. The drinker is not only made less efficient physically and mentally, but he loses in self-respect, and his powers of judgment are impaired. Poverty, wretchedness, vice, and crime are common accompaniments of the habitual and excessive use of alco- holic drinks and narcotics. At no time does the victim of alc'oholic drink plan to make a wreck of his life and man- hood by becoming hopelessly enslaved. His helplessness in an attempt to regain wasted strength of body, and to reassert control over himself, calls for pity. In his home there are those who are innocent sufferers, and the com- 74 GENERAL SCIENCE munity, too, suffers loss in the worth and excellence of its citizenship. Parents who are users of alcoholic drinks are responsible for lessened vitality in their children due to alcohol. The children of such parents are often afflicted by physical weaknesses, and are less likely to live through infancy. So readily does one become a victim of an uncontrollable appetite for habit-forming drugs and alcoholic drinks that self-protection makes it necessary to shun the company of those who indulge themselves regardless of the risks taken. w~ nfmm JL JL 1 1 . . D MALE O FEMALE fmf. A - ALCOHOLIC FEEDLEMIMDED FIG. 30. Laws of heredity are well established for both plants and ani- mals. The diagram shows what is likely to be true of children and grand- children where a man addicted to the use of alcoholic drinks marries a feeble- minded woman. The histories of such unions confirm experimental results in the breeding of plants and of the lower animals. It is only an exercise of good judgment to avoid any com- panionship and all social relationships where the price is likely to be the undermining of the health, and slavery to the use of intoxicating liquors and narcotics. Boys beginning the use of tobacco should have knowledge of the fact that the use of it very often seems to prevent a proper development of body and mind. Only a small per cent of school boys who are confirmed smokers are able to keep their standing in school work, or later to secure and retain the most desirable positions, Alcohol and narcotic HEALTH AND WELL-BEING 75 Jrugs are never to be used in any form save as prescribed by a physician, and are always to be shunned the same as other poisons. Perhaps one of the most notable outgrowths of the great world war of this generation has been the restrictions imposed by the warring nations upon traffic in intoxicating drinks. In Russia this at one time amounted to a prohibition of the manufacture and sale of vodka, the national drink. The government of China years ago awoke to the debauching effect upon its people of the extended use of opium. But it has been within the last few years only that conditions have become favorable for the stamping out of its unspeakable evils. Through national legislation known as the Harrison law (1914), the American people have at last resorted to drastic measures to restrict the increase in a traffic in narcotics that had come to number its victims in all parts of this country by the thousands. It not only impoverishes them as indi- viduals, but it wrecks them in body and mind, and their degeneracy constitutes a standing menace to the peace of society. This law seeks so to control the dispensing of the more powerful narcotics and habit-forming drugs (except alcohol) that their use shall be solely for medical pur- poses and not at all for dissipation. Society has not hesi- tated here to deny to the individual the right to ruin himself, becoming a burden to his family and to the community rather than a constructive factor in both. It has under- taken to punish those who seek profit in this traffic regard- less of individual and public welfare. The activities of very many of the organs of the body are maintained by impulses from nerve centres not controlled by the will, and these activities are sustained independently of any attention or thought on the part of a person. A great many of a person's voluntary acts and efforts, too, may be.- 76 GENERAL SCIENCE come more or less automatic after a time. The control of them as exercised by a person in early life may be almost or wholly lost. Where any certain sensation is received over and over again at any nerve centre, and the reaction to it results in nerve impulses that bring about the same kind of an act, there comes a time when the mind gives these sensations no further special attention. The reaction (motor impulse) occurs when the sensation is received without any considerable thought being given to it. A "nerve-track" of sensory and motor impulses has been established through the nerve centre that may not at all involve conscious effort of will. Only by exercise of long-sustained and powerful self-restraint can these motor impulses be brought again under control of the will, and the physical condition within the nervous system changed. Physiologists thus explain "habit" as a state of the body. Long continued use of alcohol even in small portions so affects the nerve centres as to destroy more or less com- pletely the power to control acts prompted by certain sensations known as "cravings," or an abnormal appetite. Even the sight or smell of liquor may arouse desires that are not controllable by the victim of alcoholism. These cravings constitute the misery and unspeakable torture endured by those who have become slaves of "habit-forming" drugs and preparations when they are denied the ever-increasing amounts demanded by the shattered nervous system, or when they are struggling to be free of these habits. The knowledge that the craving is relieved by a further supply of the drug becomes sufficient incentive for any act that will furnish relief for the craving. The users of patent medicines are always in danger from these evils. Most of such medicines depend upon narcotics in them to afford relief from pain or to bring about sleep, HEALTH AND WELL-BEING 77 and upon their alcoholic content to arouse an entirely false hope of speedy recovery from illness. Only a trained and experienced physician may safely be trusted to determine the nature of any serious ailment (" diagnose" it), and to prescribe the. treatment to remove its cause. "Soothing syrups" for infants, and " headache powders" for adults, depend upon the presence of powerful narcotics in small quantities to deaden pain, and to induce a more or FIG. 31. Percentage of alcohol in a patent, medicine formerly having a large sale. less unnatural sleep. Continued use of soothing syrups and "colic cures" with infants is likely to stunt their development in body and mind, and leave them sickly and unfitted to ward off the diseases of infancy and childhood. The various cough mixtures, remedies for catarrh, and "cures" for colds are likely to contain narcotics whose purpose is to deaden the sensibility of the inflamed linings of throat and air passages. While temporary relief in some cases may be experienced, the system at large is seriously deranged by use of these drugs. That the ill-effects of these drugs may not be imme- diately apparent does not lessen the harm wrought every time they are administered, nor avert the risks taken in 78 GENERAL SCIENCE their use. Even the reputable physician who has a full understanding of the physical condition of the patient should be exceedingly cautious in prescribing any habit-forming drugs 1 . The use of medicines at all times is chiefly for the purpose of bringing about conditions of the body favorable for its recuperative powers. Drugs afford at the best but a negligible amount of energy or nourishment for the body, and contribute nothing to the store of "life" as it exists in the protoplasm of the cells. No discussion of the abuse of various drugs and prepara- tions to benumb the nerve centres, and produce an unnatural, unconscious state, is complete without mention of the bless- ings to humanity in the use of anesthetics. The use of the vapors of ether and of chloroform to produce insensibility to pain in the extraction of teeth by dentists, and as used extensively by physicians and surgeons in their practice, dates back to the years 1844-1847. The freedom from torture under the knife of the surgeon, and the relief given in times of excruciating pain by administering an anaesthetic, can be fully appreciated only by those who have had some experience. The elimination of the exhaustion from endur- ance of suffering, and the avoidance of the shock to the nerve centres resulting from great pain, make likely a more prompt rally and a more speedy recovery than other- wise would occur. It must not be overlooked that adminis- tering an anaesthetic is always attended by risk to life, and that preferably it should be given by an experienced physi- cian only. 1 In the gth Revision of the U.S. Pharmacopoeia (Sept., 1916), an authority on medicinal preparations used in this country and recognized as a standard in all courts of law, no use of whisky, brandy, or wines as medicines is included. Alcohol has an industrial use as a solvent of various substances which have medicinal value, but such preparations are used in spite of their alcoholic content rather than because of it. HEALTH AND WELL-BEING 79 SUMMARY Alcohol and the narcotic drugs act powerfully upon the nerve centres of the body. The effect is to deaden them temporarily. As a result the activities of the various organs of the body are deranged, and the energies of the body are used in overcoming the ill-effects experienced. The irritated nerves in the various tissues affected by the alcohol rouse the whole system to increased activities, and this is followed by a period of depression both physical and mental. Any continued use either of alcohol or of any narcotic is likely to produce such an irritated state of the nervous system as to demand further deadening effects upon it to satisfy the "craving" that has been aroused. The victim of the "drug habit" or of alcoholic drink finds relief only in further indulgences. The protoplasm of the cells is harmfully affected, interfering with the growth and nourishment of the brain and of the whole body. So serious is this that the chances of recovery from sickness of any kind is found to have been lessened by even moderate use of alcoholic drinks. The use of tobacco during youth interferes with growth as cell division, stunting more or less the development of the brain and of the rest of the body. Powerful drugs of any kind, including alcohol and the various nar- cotics, should never be used save upon the written prescription of a skilled physician, and only after a personal examination by him to determine the exact nature of any ailment. It is but a remote chance that the drugs contained in a patent medicine will prove the best treatment for any one whose health is impaired. By reason of the stimulating effect of the alcohol contained in a patent medicine, and the deadening effect of its narcotics on any pain experienced, false hopes of recovery are aroused by its use only to be cruelly disappointed. The time thus lost may make impossible any recovery later even under skilled medical treatment. Soothing syrups and colic cures for infants, and headache powders for adults, contain narcotics in varying proportions, and should never be used save under medical advice. The introduction of anaesthetics for use in dentistry, in surgery, and in medical practice generally, has conferred an almost priceless benefit upon suffering humanity. Under the provisions of national legislation in the so-called Harrison Act regulating the sale of narcotics, it is sought to have a written record of sales from the importer or manufacturer to the consumer. 8o GENERAL SCIENCE Druggists, physicians, and any others licensed to dispense these drugs, are held responsible under heavy penalties for any use of them for other than medical purposes. No sales are permitted for purposes of dissipation on the part of those who have the drug habit. Where like sensations are always followed by the same kind of responses, the brain in time gives less and less attention to either the sensations or the responses. There comes about a condition where nerve centres other than those involved in making choices and direct- ing the acts of an individual take care of the whole matter. Indeed, so far may this loss of the will power over these acts have gone that reason and will seem to be unable to regain control over them. The person so far as that particular habit is concerned is a hopeless slave, though at times he may have the greatest desire to break from it. GENERAL SCIENCE AND RIGHT LIVING Psychology (sl-kol'o-ji) deals with what is known of the activities of the human mind. A better understanding of the conditions for these activities should lead to a better intel- lectual and moral life. It is necessary that the psychologist know very definitely the structure and physiology of the brain and nervous system of the human body, and be well versed in biology. But it is : neither necessary to be a scien- tist, nor to have gone to college, in order to know the condi- tions essential for growth into the best types of manhood and womanhood. It is to be kept in mind that those characteristics which distinguish mankind from the brutes are the result of a slow process of human development. Education through schools has to do with this development of intellectual and moral natures in individuals, and for its best results requires time and favorable conditions. While schools are maintained as one of the chief agencies to this end, it must be remembered that a large part of what any one knows and is able to do has been gained outside the schoolroom. Influences that very largely shape one's choices and fix one's ideals of life are those of the home and its surroundings HEALTH AND WELL-BEING 81 during childhood and youth. Habits of thought and of action formed then are likely to control in later life. Self- indulgence during early life in ways and manners harmful to the individual himself and offensive to others gives rise to social and personal limitations during the later years of manhood and womanhood. The degree of self-control and self-denial learned and practised during youth is a very satis- factory measure of any growth towards a well balanced complete manhood and womanhood. One of the chief ends of school attendance is to acquire ability in making those choices in one's manner of life, and in all matters of skill and knowledge, that contribute most to the well-being of the indi- vidual himself and of other people generally. In acquiring information, in grasping the relationships of facts, and in making applications of knowledge, unless there is a clear discernment on the one hand between what is for the well-being of the individual and of society, and on the other of what is degrading for all, the purposes of schools may be largely defeated. The development of an intellec- tual and moral nature in an individual is a relatively slow process requiring a lifetime. The conditions for this develop- ment are in large part within the control of the individual himself. It is his own choice whether his educational prog- ress shall be toward the formation of habits that experience and science have shown to be best, or toward those whose results are harmful to himself and to others. Enlightenment in hygiene and sanitation, and in the ways of right living generally, assumes that every one who is at all reasonable and sane will do what is known to be best, and avoid doing what is either questionable or absolutely harmful. One of the fundamental facts concerning growth from childhood into self-directing manhood or womanhood is the gradual assumption of responsibility, and a manifest readi- ness to discharge duties without compulsion. Regardless 82 GENERAL SCIENCE of one's age and bodily growth, any one who must be made to do what he ought to do, and who must be compelled to refrain from doing what is wrong, is not yet grown. He is yet a child in the ways of right living. As persons grow older in years, and come to some degree of maturity of body, it is only reasonable that their conduct should give evidence of growth into the better types of manhood or womanhood. Knowledge gained in schools finds its chief value and most fitting expression in lives that are guided more nearly aright as result of such teachings. People who manifest no regard for the welfare and rights of others may very properly be said to exhibit criminal tendencies. These manifestations range all the way from what is commonly called selfishness to that utter disregard which does not hesitate to destroy human life for gain. Not all practices included in such a sweeping classification are illegal by any means, i.e., prohibited by law. The liquor traffic is not only permitted in many communities but legally authorized by license. It is carried on regardless of an appalling list of evils that result from it both public and private. The adulterations of foodstuffs, the use of harm- ful preservatives, and the traffic in habit-forming drugs, have been made illegal. All of them involve the robbing of one person by another of health, of ability to earn a liveli- hood, and of possibilities for advancement in general welfare. In individual relationships in life the motto "Quid pro quo," meaning to make full return in value for whatever one gets, is conducive both to manhood and to good citizenship. Activities that largely control the development of the body and mind occur during the years of childhood and youth. There is lack of experience then concerning the wisdom of what ought to be done. Understanding of the relationship of cause and effect in matters of health, and of the conse- quences of any unwise course in life, comes only through years HEALTH AND WELL-BEING 83 of experience and of instruction. The age of discretion and of responsibility in conduct is slowly attained. The experiences and counsel of those who are older, whether written in books, listened to at home or in school, or witnessed in lives about us that are worthy of being followed as examples, make a wise course in life possible until personal experience can safely modify or replace these safeguards. Any failure to direct one's self aright does not destroy all growth previously made toward manhood or womanhood. Habits are the results of repeated efforts, and the importance of the single act as explained by the physiologist and the psychologist lies in the knowledge that another like act becomes more probable. SUMMARY The larger part of what any one knows is learned usually outside school. It may be considered that the chief purpose of schools is to stimulate and direct a love of knowledge, and to give efficient training in its acquisition and effective use. What has been learned by men down through the ages in any one of the sciences has been so classified and related that it is possible in a year's study to get a good general knowledge of it. Knowledge becomes of largest worth when it promotes our own highest welfare, both of body and of mind, and when through us it benefits others in largest degree. Habits of any kind become fixed only through years of repetition. Both the training and the instruction given in schools should be directly concerned in fitting every one habitually to make more intelligent choices in his manner of life, and in all matters of skill and of knowledge. The habits formed in connection with doing school work should be such as to make men and women more efficient in life, more self-reliant, and more persistent in the solution of life's problems. One's whole life should be more sane and better directed by reason of attendance upon school. . The person who must always be told what to do and when to do it, who must be made to do what he ought to do and made to refrain from doing what he ought not to do, is not yet grown up. He remains a child in development whatever his age in years may be. 84 GENERAL SCIENCE All hope of the progress of mankind, and one of the chief reasons for maintaining schools, is that each individual and each generation in turn may early become acquainted with the gains in knowledge made by the race. This renders it unnecessary for anyone to repeat the mistakes that others before him have made. Many of the evils experienced in the lives of people are the direct results of wrong habits formed before the full significance of these habits and of their results could be understood. Exercises 1. Explain the need of recreation and amusements. What unmistakably .distinguishes them from dissipation? 2. Upon what set ("system") of organs of the body does any narcotic (including alcohol) directly act? Explain the "stimulation" '(increased activities) from the use of small portions of narcotics. 3. What is meant by the drug habit? How is it that people become slaves to it? Why is the habit unlikely to be overcome? 4. What is meant by "patent medicines?" Account for their extended sales. What constitutes sufficient argument against their use? 6. Name some of the conditions a person must observe in order to do his best and be at his best. 6. What is meant by a sound body? Name some characteristics commonly accepted as evidence of a sane mind. 7. What is understood by the term food, whether for plants or for animals? 8. Under what conditions may no harm come from being up late nights? What relationship should exist between one's kind of recreation and the nature of his employment? 9. Whence is derived the "life" of each succeeding generation of plants and of animals? 10. Why may it be well to abstain from eating when one has a cold? Why may it be well to take hot drinks and a vapor bath at such a time? 11. What constitutes (a) temperate living; (b) a "simple life"? 12. What should be the great service performed by a physician for his patients, and the chief aim of his efforts? What has been found true of the recuperative powers of those who use alcoholic drinks? 13. What only can medicine do for the restoration of wasted energies and a broken-down body? 14. In human society when must a person be prevented by others from doing as he pleases? 15. Give illustrations of the statement that those who will not deny them- selves in observing nature's laws will be denied by her, as well as punished for past offenses. IV. WATER, AND ITS USES SOME PROPERTIES OF WATER Water is indispensable in the life of all plants and animals. In the human body it makes possible the solution (digestion) of foods. It is the means employed in the body for removal of waste through the skin, bowels, and kidneys. It keeps moist the tissues so that they can perform their several functions. In Physics a study is made of water as a type of all liquids. In Chemistry both its physical and chemical properties are studied, together with its usefulness in pro- moting chemical change and in carrying on the chemical processes. In the study of Physical Geography, and in Meteorology, water as an agent in the changes that occur is of first importance. In matters of hygiene and sanitation, and in the affairs of the household, the importance of water in daily life can scarcely be emphasized sufficiently. In the affairs of men and of nations water is a highway for foreign and domestic commerce, while water and steam furnish a large part of the power that turns the wheels of the world 's industries. Any extended consideration of its usefulness to individuals and to mankind generally by reason of its properties and its abundance leads into every field of human activity. . All matter, including liquids and gases, is supposed to be made up of minute particles called molecules. These are too small to be seen through the most powerful microscopes. It is further supposed that these molecules as units of matter are separated by spaces relatively large as compared with the size of the molecules themselves. And it is believed that these molecules are incessantly moving back and forth in 85 86 GENERAL SCIENCE these intermolecular spaces (pores), and that the degree of this motion and the consequent number of collisions among the molecules is the cause of the varying temperatures of bodies. It is believed that the distinctions between solids, liquids, and gases lies largely in the different intensities of the attractions (pulls) exerted between the molecules by the intermolecular forces of cohesion and adhesion. In solids the attractive forces dominate, and the solid retains a form of its Own. In gases the moving molecules drive one another apart, and gaseous matter must be confined. Left unre- stricted, gases would expand indefinitely filling all space open to them. Liquids are an intermediate condition be- tween solids and gases, and possess enough of freedom in the motion of their molecules to assume the form of a containing vessel. Molecules escape from their upper surfaces into the atmosphere more or less at all times when left uncovered. The rate of this evaporation varies with the kind of liquid, its temperature, and the capacity of the atmosphere for holding that particular vapor. Many liquids are said to be volatile because they must be kept in stoppered bottles or other containers to prevent excessive waste due to evaporation. Water is boiling when it is changing to a vapor within the liquid mass. For pure water under one atmosphere of pres- sure, .i.e., when the barometer reading is thirty inches (76 cm.), the boiling temperature is 100 C. (212 F.). When water is confined in a closed vessel, as in the boiler of a loco- motive, and the gaseous (steam) pressure upon it becomes more and more, the water must be heated hotter and hotter to keep it boiling as the pressure upon it increases. Under two atmospheres (thirty pounds per square inch) the boiling point becomes about 120 C., and at fifteen atmospheres becomes about 200 C. If at any such high temperature the pressure on the water surface be suddenly released, the heat WATER, AND ITS USES 87 contained in the water may convert the whole liquid mass instantly into steam. By use of " vacuum pans" having air-tight covers, and with a pressure upon the liquids contained in them kept less than one atmosphere by use of an exhaust (air) pump, the boiling may go on rapidly at temperatures much below 100 C. By reason of a lessened atmospheric pressure due to increase in altitude the boiling point of water is lowered about one degree in temperature for approximately 1000 feet elevation. At Denver one mile above sea level the boiling point is approximately 95 C. In the use of rubber bags containing hot water as a source of warmth through a period of several hours, we have an illustration of another important property of water. Differ- ent bodies having the same weight and same temperature give off widely different amounts of heat in cooling through the same number of degrees. This is another way of saying that the same amounts of heat taken up by equal masses of different substances having the same initial temperature give widely different final temperatures to these masses. Water has the highest specific heat of the various liquids and solids. Where equal weights of mercury and water are heated equally, the rise in temperature of the mercury is about thirty times greater 1 . Dry land surfaces (soils) heat much faster and get much hotter under a summer sun than bodies of water, cooling off during the night much more rapidly and to a much lower temperature. A cubic foot of water weighs about sixty-two and one-half !The specific heat of any substance may be defined as the number of cal- ories of heat necessary to raise the temperature of one gram of the substance one degree centigrade. The specific heat of water is i.oo (see page 147), and the specific heat values of the following substances are given merely for illustration: Mercury (solid) 0.033 Aluminum 0.214 Iron 0,113 Ice 0.550 88 GENERAL SCIENCE pounds. In freezing it expands about one-tenth of its volume, and a cubic foot of the ice that is formed (not the whole of the cubic foot of water) weighs about fifty-seven pounds. The density of ice is about nine-tenths that of water. This explains why ice as it forms on the surface of water in winter does not sink to the bottom, and why ponds and streams do not become frozen solid during a winter. If large bodies of water did freeze solid, it is unlikely that this ice would ever thaw very much below the water surface. The heat of the summer's sun upon it would be used largely in vaporizing the surface layer of water. All marine life would be destroyed, and the waters would be icy cold all summer. Winds blowing over this ice cold water would check or destroy the growth of vegetation. With the den- sity of ice so nearly that of water, it is calculated that about nine-tenths (.92) of the volume of an iceberg is submerged however much it towers above water surface. Within a temperature range from 32 to 212 F. (o to 100 C.) water exists as solid, liquid, and vapor. No other substance has so narrow a range in temperature for all three states. All waters coming out of the ground are likely to contain more or less of minerals in solution. Inland lakes and seas such as the Great Salt Lake of Utah, whose waters have no outlet other than by evaporation, become increasingly saline as minerals in solution are washed in to be left there. The waters of the ocean contain nearly 3 per cent of common salt. " Mineral springs" contain certain dissolved compounds that have more or less of medicinal value. Usually these waters as sold on the market are " car- bonated, " i.e., made to hold under pressure considerable carbon dioxide gas. When this water is poured into an open glass, and is under only the ordinary atmospheric pressure, effervescence occurs by reason of the escape of this gas into the air. WATER, AND ITS USES 89 Water itself is practically incompressible even under enormous pressure. Because of this fact the density of the water in the depths of the ocean is. approximately the same as at the surface. Bodies heavy enough to sink beneath the surface will go to the bottom. This incompressibility of water is in striking contrast with the ready compressibility of gaseous matter such as the atmosphere. "Soda water" is carbonated drinking water sweetened and flavored by use of fruit syrups. Substances chemically prepared, and having flavors similar to those of various fruits, are sometimes used in place of the real fruit because of cheapness. Their use may be attended with harmful results, especially for those whose digestion is at all impaired. SUMMARY The important uses of water are too numerous to be named here. Very many of these uses are named elsewhere in this text in different connections. In agricultural, commercial, and industrial life, and in all relations of life affecting health and well-being, water occupies a most important place. A detailed study of water as a typical liquid is made in Physics. Brief studies of other liquids can then be made by comparison. Its composition, and its usefulness in chemical changes, are both empha- sized in Chemistry, while in the other sciences the uses of water appear in manifold relationships. The boiling and freezing temperatures vary for different liquids These temperatures are changed for any liquid by variations in atmos- pheric pressure, and by the presence or absence of substances in solution. The high specific heat of water, and the excessive value of the heat involved in its vaporization, are of utmost importance in any con- sideration of climate. Abundant as are the waters of earth, it is a most difficult problem to secure a supply of water sufficiently free of organic and mineral matter, and of disease germs, to warrant its use for household purposes. Oceanic waters, and those of certain inland lakes, seas, and springs, hold in solution so much salt, "lime," and other minerals as to be unfit for drink and for the preparation of foods. 90 GENERAL SCIENCE Water can hold gases as well as solids in solution. Both marine and land plants get the needed supply of oxygen for their tissues from the water. Fish are provided with special organs known as gills to get from the water that passes in and over them the oxygen they require. When water containing any gas is freed from pressure, more or less of the dissolved gas will escape. This is seen in "soda water," and in all carbonated mineral waters. VAPORIZATION AND CONDENSATION As elevation above the earth's surface increases it is found that the pressure exerted by the atmosphere decreases. In the study of Physics it is also found that when the pressure upon any gas is decreased the gas not only expands but its temperature falls. This result follows from the molecules being further apart. As atmospheric moisture rises in the form of invisible vapor of water it expands and cools, and the formation of clouds with or without rain or snow may follow. The air may cool, also, by reason of radiation of its heat out into space independent of any expansion. Clouds and fogs, consist of minute droplets of water as a liquid. These cloud masses of water particles are heavier than air, and are all the time settling toward the earth's surface. Where the under surfaces of the cloud mass come in contact with warmer air, or air that is unsaturated, the liquid particles change back into the vapor form. But while the cloud is thus wasting below, it may be forming anew elsewhere, especially at the upper surfaces. Thus the form of the cloud is more or less constant. The amount of rainfall in some of the regions of earth is a negligible quantity, while the amazing total of 500 inches or over forty feet a year is recorded for the region northeast of the Bay of Bengal. Where the annual rainfall is under twenty inches, the raising of crops without irrigation is hazardous. The distribution of the rainfall through ^the growing season is a factor quite as important as the matter WATER, AND ITS USES 92 GENERAL SCIENCE of a few inches more or less annually. In the region just east of the Rocky Mountains the rainfall is deficient, and just east of the Sierra Nevadas in Nevada, Utah, and adja- cent regions, it is scarcely five inches a year. On the north Pacific Coast of the United States the rainfall is about seventy inches per year. AVater vapor when cooled rapidly and to a sufficiently low temperature forms beautiful crystals known as frost. These may gather on window panes and other exposed surfaces, or may float about in the air. Snow flakes may be considered as masses of frost crystals. Ice and snow and frost form at temperatures below 32 F. (o C.), and melt when above this "freezing point." Ice melts at 32 F. as heat is added to it, and water at 32 F. freezes as heat is abstracted from it. It must be remembered, however, that vaporization of water occurs at any temperature even from the frozen (solid) state. When melted iron is run into moulds, it is found when solidified to have increased enough in volume to take any markings that may have been on the sides of the mould. Iron and steel castings are made in this way, and any desired patterns may be had upon their surfaces. When cast iron is broken a crystalline structure is easily noted by use of a magnifying glass. The increase in volume is explained by the added space required for the newly formed crystals whose regular forms do not fit as closely together as did their molecules before the crystals formed. The change of water to ice is similar, and experiences with broken pipes are common when water is allowed to freeze in them. A block of ice is just a mass of more or less perfectly formed crystals indistinguishable save when they are forming or when they fall apart as the ice "honey-combs." The process of vaporizing solids, and then condensing the vapor to the solid state once more without passing through the liquid state in either case, is called sublimation. The WATER, AND ITS USES 93 solid that has thus passed through both changes is a subli- mate. Distillation is the vaporization of a liquid and the condensation of this vapor back to a liquid state again. Air containing much moisture does not allow heat to pass through it readily. When a cloud passes between an ob- server and the sun on a hot day in summer the relief due to absorption of the sun's heat within the cloud mass is very noticeable. Not only does the total amount of water per cubic foot in the air vary at different times, but the capacity of the air for holding water vapor varies widely with changes in its temperature. The ratio of the amount of water vapor pres- ent in the air at any time to the amount that the air might then hold is known as relative humidity. It tells what per cent saturated the air is at that time. Air is saturated when the humidity is 100 per cent. Grams of water vapor per saturated cub' c meter. -J 5' 10 15 Tempera ture Centigrade FIG. 33. Capacity of the air for moisture at different temperatures, j SUMMARY The invisible water vapor in the atmosphere when cooled sufficiently is changed back into the liquid state. This cooling may result from incoming cold air as a cold wind, or it may occur when the moisture- laden air rises and mixes with air in the upper colder levels of the atmosphere. Then, too, cooling may be the direct result of expansion of air containing water vapor as it rises where the pressure upon it becomes less and less. 94 GENERAL SCIENCE The cloud masses consist of minute droplets of water which are con- tinuously settling toward the earth. While in a general way their forms persist, clouds are all the time undergoing change by wasting at the lower surfaces and by reforming higher up. When the temperature of the air falls below freezing, the water vapor it contains may be changed to frost crystals. Masses of these crystals form snowflakes. When the ground, the roofs of buildings, and other surfaces are below freezing temperature, and the air is warmer and moisture-laden, frost is likely to form upon the cold surfaces. The presence of water in the air, whether as vapor or as cloud par- ticles, serves more or less as a blanket, and lessens the rate of xrooling of the earth's surface at night. As the air cools at night its capacity for holding moisture decreases. With the same amount of vapor of water present in the air, its relative humidity or per cent of saturation increases. In the early evening this increase is often rapid. Condensation is the opposite of vaporization, and both processes are involved in distillation. Natural distillation, with the sun as source of the heat, plays a large and important part in weather con- ditions. The rainfall of any region that is destitute of large water surfaces is dependent in great part upon winds blowing from other regions where vaporization is abundant. These winds, if unduly con- tinued, result in a wet season for inland areas, while their deflection or cessation for causes unknown accounts for a dry season. HEAT OF VAPORIZATION, AND OF FUSION It has been found that to change the temperature of one pound of water one degree on the Fahrenheit thermometer always involves the same amount of heat. It makes no difference whether the water is warmed or cooled. This quantity of heat is used as the unit in computation of heat values, and is known as the British thermal unit. Then if water weighing twelve ounces (three-fourths pound) has its temperature raised 6J^ F., the water has gained % X 6^, or 4% British thermal units. Most science texts make use of the metric system of weights and measures. It is much more simple to learn WATER, AND ITS USES 95 and to use, and its general adoption in business and in schools is desirable. Its heat unit is called the calorie, and its value is the heat involved in changing the temperature of one gram of water one degree of the Centigrade thermometer. It has been found by repeated experiments, carefully conducted in physics laboratories, that when ice melts about 79 calories of heat disappear for every one gram melted. In other words the heat of fusion of ice is 79 calories per gram. In similar experiments the heat of vaporization is found to be about 536 calories per gram of water. The meaning of these values is somewhat difficult to grasp at first. Let it be illustrated in this way. To cool boiling hot water (100 C.) down to the freezing temperature (o C.) involves the liberation of 100 calories of heat per gram. If that same one gram of water at o C. is changed to ice at o C., involving a change of state from liquid to solid but no change in temperature, almost 80 calories of additional heat are liberated the heat that was required to keep the gram of ice in the liquid state. Even more striking is the meaning of the 536 calories of heat of vaporization of water. In the condensation of invisible water vapor 1 whose temperature is 100 C. to water that is boiling hot (100 C.), involving as it does a change of state without change of thermometer readings, there is 5.36 times as much heat set free as when that same water is cooled from its boiling temperature to the freezing temperature. A common use of the great heat value of this " latent heat" of steam is in the warming of. rooms and buildings by the condensation of relatively small weights of steam in radia- 1 The so-called steam that is visible consists of a cloud of minute water particles resulting from the condensation of invisible water vapor. 96 GENERAL SCIENCE tors. These are connected by means of pipes with boilers that are often located at considerable distances away. It is, however, in the study of Physical Geography, and of Meteorology, that one comes to have some true notion of the vast scale upon which heat is made "latent" in the vaporiza- tion of enormous quantities of water by the sun, and then later set free as this water vapor condenses. These changes are going on everywhere over the earth, but on the largest scale in the tropical regions. Our weather, and the intensity of storms, are both directly related to the heat values in- volved in these changes in the state of water. It will be necessary to keep in mind that other substances than water exhibit like phenomena, and that the value in calories of their heat of fusion and their heat of vaporization varies with the substance. SUMMARY Heat like other forms of energy can be measured. The units em- ployed for this measurement are the calorie, and the British thermal unit. There is a wide variation in the amounts of heat required to melt equal weights of different solids, and to vaporize equal weights of dif- ferent liquids. The heat of fusion for water in the form of ice is 79 calories per gram, and for its vaporization from the liquid state is 536 calories per gram. The heat used in changing water as a liquid into vapor, whether on the stupendous scale of natural vaporization or in steam-heating plants or elsewhere, is wholly set free when condensation of the vapor occurs. To continue wearing damp or wet clothing, and to allow it to dry out while being worn, involves the abstraction of much heat from the body. This loss of heat ordinarily can ill be afforded. Soils containing water will absorb large amounts of heat with small rise in their temperature. This is by reason of the high specific heat of water. Then, too, by reason of the extremely large value for the heat of vaporization of water, soils that are water soaked are likely to remain cold and unfit for plant growth late into the Spring, and after periods of wet weather. Soils with good drainage warm much more rapidly. WATER, AND ITS USES 97 Exercises 1. When persons climb mountains, or go up into the clouds in balloons, what are the clouds found to be? 2. Why does not all the water of the atmosphere fall to earth (a) when it is in vapor (gaseous) form; (b) when in minute droplets as in fog? 3. Why is it that in winter we sometimes can "see our breath?" 4. Explain the thinning out and disappearance of the clouds of early morn- ing as the sun rises higher and higher. Why is it that at other times as rain continues the clouds break away giving place to clear skies? 6. Whenever there is an inch of rainfall, (a) what is the number of cubic feet of water that falls per acre of land; (6) how many gallons (231 cubic inches = one gallon) ; (c) how many tons (one cubic foot = 62.4 pounds) ? 6. Name and describe several forms of clouds. 7. Aside from rainfall, what important part in nature is served by clouds? 8. How may an ample supply of water for drink and for cooking purposes be provided on long journeys by ship? In what way may a supply of ice be provided? 9. What is meant by "humidity" of the atmosphere? What is the exact significance of the term "relative humidity?" 10. Whence comes the heat, directly or indirectly, for natural distillation? 11. Be ready to quote and interpret the last stanzas of Longfellow's Rain In Summer. 12. What may explain in part the refreshing coolness that frequently follows a summer shower? What relation is there between the temperature of soil under a summer sun and the abundance of water in it? Why is this so? 13. Explain the heating of rooms and buildings by steam as a phenomenon of heat of vaporization. What is true of the temperature of water boiling freely in a tea-kettle as it is heated more and more? Explain. 14. Explain how the melting of ice and snow, and of the frost in the ground, delays the coming of warm weather in spring time. 15. What is meant by the heat of fusion? Describe an experiment to explain it. 16. What is a calorie? What is the value in calories of the latent heat (a) of steam; (6) of ice? 17. What is the part played by moisture in the atmosphere in equalizing throughout the year the temperatures of coast regions? Account for the extremes of temperature of inland arid districts by day and by night. SOLUTION, DIFFUSION, ABSORPTION, AND OSMOSIS The phenomena of absorption, diffusion, solution, and osmosis are easily understood on the hypothesis that a chief 9 8 GENERAL SCIENCE NH. difference between the solid, liquid, and gaseous forms of a body is in their rate of molecular movements, and in the size of the spaces (" pores") between the molecules. An hypothesis in science is a supposition used as an explanation of phenomena. Systematic advance in scientific knowledge makes large use of hypotheses. It must always be remem- bered, however, that these hypotheses are based upon what is known to be true, and that they are always subject to change to accord with any newly discovered facts. A belief found to have wide application, and always found true to the facts of the natural world wherever it is applicable, is known as a "law" in science. It j j I (4 in H2S04 is two. In the study of Chemistry one must become able to deter- mine the valency of elements in compounds. As formulae of the simpler chemical compounds are met in this text and elsewhere it is worth while to notice what seems to be the valency of different elements and of any radicals. For example, it will be noted that the valency of Ca and of S is two in the compounds CuS and Ca(OH) 2 , and that of the radical OH is one. SUMMARY A base is a compound of hydroxyl (OH) and any metallic atom or radical. An acid is a compound containing hydrogen atoms replace- able by metallic atoms or radicals. A salt is a chemical compound that may be considered as formed when any of the hydrogen of an acid is replaced by a metal. In the break-up (dissociation) of molecules when certain substances dissolve, the metallic atom or group of atoms is conceived to be posi- tively electrified, and the negatively electrified atom or group is non- metallic in character. The behavior of hydrogen ions is the same as that of the metallic ions. 1 84 GENERAL SCIENCE The chemist explains the acid effect of solutions upon litmus or other test papers ("indicators") as due to the presence of free hydrogen ions, while the alkaline effect is due to the presence of free hydroxyl ions. The formula used in place of the name of any chemical compound not only is a shortened way of writing its name, but it also states at a glance what elements enter into the compound, their grouping, and their weight proportions. All this must be known by the chemist before the formula can be written. An equation sets forth what substances enter into a chemical change as factors, and what are the products of the change. The combined weights of factors and of products must be equal, as must the number of atoms on the two sides of the sign of equality. Any use of equation writing to express what is thought to have occurred, or what may occur in a chemical change, is liable to lead to wrong conclusions. Its proper use is to set forth what is known to have occurred. It is a means for stating facts that have been verified by exacting tests. The valency of any atom or radical is simply a number. It tells how many hydrogen atoms will replace the atom or radical, or with how many hydrogen atoms it will unite. A radical is a group of atoms which in chemical changes behaves like a single atom. ELECTRICITY AND CHEMICAL CHANGES In the study of electricity from cells there is reason to believe that the electrified condition passing along a circuit and constituting the current is being maintained by chemical changes occurring in these cells. It is also assumed that this outward passage of the electrified condition is by way of the carbon plate in the dry cell, or copper plate in the simple cell. Where the terminals of a broken circuit are put down into an electrolyte, that electrode by way of which the current enters the electrolyte is called the anode (way in), while the one from which the current leaves the electrolyte is known as the cathode (way out). When a current sufficiently strong is passedjthrough dilute sulphuric acid as the electrolyte, SOME CHEMISTRY OF EVERYDAY LIFE 185 gases appear at both electrodes. By collecting a sufficient amount of them for testing, the gas at the cathode is found always to be hydrogen, and the gas at the anode is always oxygen. These gases are apparently from the decomposition of some of the water (H 2 O) of the solution. The process of breaking up chemical compounds by passing an electric FIG. 59. Silver plating. The passage of the electric current through the solution of a silver compound results in the deposition of a thin coating of silver over the exposed surfaces of articles serving as the cathode (-electrode). current through their solutions is called electrolysis (electrical analysis) . Instead of the sulphuric acid in dilute solution as electro- lyte there could be used a solution of some compound of silver. With a current sufficiently strong, silver as a metal in the pure state would then be deposited on the cathode, forming a thin even layer or " plate" over any suitable 1 86 GENERAL SCIENCE object employed as the cathode. Extra thick deposits would constitute " double-plate " or " quadruple-plate." In a similar manner nickel plating uses a solution of a com- pound of nickel for the electrolyte, and copper plating uses a solution of a copper compound. In Electricity as in other science subjects, theory aids in an understanding of phenomena. By use of theories students can comprehend in a few lessons the significance of phenom- ena whose explanation is the result of years of patient re- search on the part of many scientists. It is to be remembered , too, that the accepted theories of science rest upon an experimental basis, and seem to be verified in all cases where they are applicable. At the same time they must never be considered as statements of what is known to be true beyond question. To aid in an understanding of electrolysis what is stated on page 181 under Acids, Bases, and Salts is conceived to be true. When some substances are dissolved, not only are their molecules separated and scattered throughout the solvent, but the molecules themselves break up into two parts each known as ions. These parts may consist of single atoms or of groups of atoms, and the more dilute the solution the larger the extent to which this dissociation is carried. In the case of sulphuric acid, the groups are considered as H 2 and S04. These electrified atoms or groups of atoms act as carriers of electricity and serve to complete the circuit of the current used in electrolysis. In the case of solutions of compounds of metals the metallic ions pass from the solution to the cathode where they give up their charge of electricity, and as atoms free of electrifica- tion they collect on the cathode as pure metal. It is found that if the anode in such cases consists of the same kind of metal as that which is being deposited, or of any impure form of it, this anode wastes as result of the electrolytic SOME CHEMISTRY OF EVERYDAY LIFE 187 action. The electrolyte will then remain at the same strength of solution all the time, and the metal from the anode will gradually accumulate at the cathode in a pure state. Chemically pure metals, such as copper, are prepared or " refined" in great quantity for the industries by electro- lytic action. When the binding posts of the piece of apparatus known as a "simple cell" are connected by a wire, and the two metal strips as terminals of this wire are put down into the acid solution of the cell as an electrolyte, the two plates of the cell may be considered as electrodes. This is true of other kinds of cells. The current set up in such a closed circuit is sup- posed to enter the cell from the external circuit by the zinc plate as anode, and to leave the cell from the copper plate as cathode. It is interesting to note that storage batteries such as are used in electric motor cars are " charged" by electrolytic action. Chemical changes are made upon the plates of the storage cells by the hydrogen and oxygen set free by the passing current. During the charging process these plates are the electrodes of the " primary current." When these chemical changes have been completed, the storage battery is " charged." The connections with the primary circuit may then be broken, and the storage battery is now in its turn capable of sustaining a current to run the car so long as a reversed chemical action continues. When the plates have been restored to their original condition chemically, the storage battery must be charged anew. The "gassing" of the storage cells at the completion of the charging process is but the escape of oxygen and hydrogen gases formed by electrolysis, and not longer used in chemical changes on the plates of the cells. The marvelous changes that have been wrought by the application of electricity in the industries is well illustrated i88 GENERAL SCIENCE in the present-day production of aluminum metal by elec- trolysis. Bauxite, an ore of aluminum, contains 50 per cent or more of alumina (A^Os) . This is separated from the other material in the ore by a series of chemical changes relatively inexpensive. Alumina is insoluble in water, and its melting point is too high for practical purposes. However, a mineral known as cryolite and imported in large quantities from FIG. 60. Manufacture of aluminum. A, A', a lining of carbon which serves as the cathode in the electrolytic action. B, melted cryolite which dissolves the oxide of aluminum as it is added from time to time. The tem- perature of the "bath" is kept so high by the passage of the electric current that the aluminum metal as liberated collects in a molten state. Greenland not only melts at a relatively low temperature, but when in a molten state it readily dissolves alumina. When a powerful electric current is sent through such a solution, the alumina is decomposed. Oxygen is given off at the anode and pure aluminum metal at the cathode. The heat developed in the passage of the current through the electrolyte keeps the material in the bath molten, and the aluminum metal is drawn off from time to time in a liquid form. SOME CHEMISTRY OF EVERYDAY LIFE 189 It is a matter of interest to note that the process at present employed for the enormous output of this metal is essentially the same as that invented by Charles M. Hall 1 in 1886. The price of aluminum metal on the market dropped from four dollars per pound to twenty cents per pound as soon as the new process could supply the demand. Aluminum ware and utensils are light, durable, and attract- ive. The density of aluminum is only 2.7 while that of iron is about 7.8. The metal neither rusts nor corrodes. The tarnish which dulls the appearance of aluminum kitchen ware should not be scoured off. It is largely an oxide of the metal, and serves as a protective coating. Strong alkalies, such as soda, should not be used in aluminum vessels except to clean them. The metal is acted upon chemically by alkalies, especially in hot strong solutions. Aluminum in a powdered form when mixed with oil serves as a paint for iron surfaces, giving them a cheerful neat appearance as well as protecting them from rust. SUMMARY In the production of electrical energy in cells by chemical changes, the value of the energy output from a cell depends upon the difference in the degree of chemical change at the two plates. To increase this difference to a maximum one of the plates usually is so chosen that no action at all takes place upon it. The plates of a cell must be immersed, or embedded, in an electrolyte whose ions serve as carriers of electrical energy from one plate across to the other thus closing the circuit. The separation of the plates by any considerable thickness of liquid, or by a porous wall such as a cup of earthenware, hinders this action and increases the internal resistance of the cell to the passing of a current. Whatever this electrical energy passing along the wire may be, its presence may be detected by its effect upon a suspended magnetic needle such as a magnetic compass. Enough heat may be developed 1 Hall was then but twenty-two years of age, having graduated the year before from college. ^ GENERAL SCIENCE in the conducting wire to be noticeable, too, and at times the wire may become incandescent. In the process of electroplating we have a good illustration of elec- trolysis. When the terminals of a broken circuit are immersed in the plating solution as an electrolyte, and a current of electricity is sent through it, the positively charged metallic ions in the liquid pass to the cathode. Here, upon losing their electrification, they are deposited as a metallic coating upon whatever serves as cathode. On the other hand the negatively charged ions pass to the anode, lose their electrification, and unite with the anode when it is of suitable material. At other times they unite with the water surrounding the anode, and again at other times escape as gaseous products into the atmosphere. It must be remembered that in this theory of the dissociation of electrolytes in solution into ions there is the most satisfactory explana- tion of what actually occurs a phenomenon that otherwise remains complex and not understood. LIMESTONE, AND OTHER CARBONATES One of the chief chemical industries is the manufacture of sodium carbonate from common salt (NaCl). The impor- tance of it, and of its related and dependent industries, requires that every well-informed person have some knowl- edge of it, at least as much as may be gained from a high school text in Chemistry. The extent of industries such as this is in no small degree an index of the industrial activities of a nation. In the Solvay process of manufacture saturated solutions of common salt are treated with ammonia (NH 3 ). This with water forms ammonium hydroxide or "ammonia water" (NH 4 OH). Carbon dioxide (CO 2 ) passed into the solution may be supposed to form carbonic acid (H 2 CO 3 ) with the water. As a final result of chemical changes that occur, sodium bicarbonate (HNaCO 3 ) or " baking soda" separates out as a finely divided solid. These chemical changes for SOME CHEMISTRY OF EVERYDAY LIFE 191 sake of simplicity are represented as occurring in a series thus: (1) NH 3 + H 2 O = NH 4 OH (2) C0 2 + H 2 = H 2 C0 3 (3) NH 4 OH + H 2 CO 3 = H 2 O + H(NH 4 )CO 3 , or ammo- nium bicarbonate (4) H(NH 4 )CO 3 + NaCl = NH 4 C1, or ammonium chlo- ride, which remains in solution + HNaCO 3 , or sodium bicar- bonate, which is precipitated. Hundreds of tons of salt are worked up daily in making sodium bicarbonate at the Solvay Works, Syracuse, N. Y. Upon heating the sodium bicarbonate sufficiently it is converted into sodium carbonate (Na 2 CO 3 ), the well-known " washing soda," one of the most extensively used of alkalies in the arts and industries. The nature of the chemical change that occurs is shown in the equation 2 HNaCO 3 = H 2 O + CO 2 + Na 2 CO 3 . Enormous quantities of sodium carbonate are used in glass- making, in soap-making, for washing powders, and in the manufacture of the important compound known as "caustic soda" or sodium hydroxide (NaOH). The wide range of uses of sodium carbonate is due chiefly to the fact that it is a cheap and effective agent to neutralize acids. It is to be noted in this connection, too, that sulphuric acid occupies the same first rank in industrial importance among acids that sodium carbonate does among alkalies. The amazing total amount of this acid 1 used in the United States, England, and Germany is expressive of the manu- facturing and commercial enterprise of these nations. A description of the making of lime from the rock known 1 According to the U. S. Census Report (1914) one hundred ninety-four establishments reported the manufacture of over four million tons of sulphuric acid. 192 GENERAL SCIENCE Million Barre/s 60 60 40 / J~~ / ^ / as limestone, and of the manner of use of this lime in building operations, may be found in Chemistry texts and other reference books. It has much of interest in itself, and its discussion may well lead to further readings on many related topics. One such topic is the nature of concrete and of cement, both of which are used in enormous quantities annually for construction pur- poses. The growth of the cement industry in this country from 42,000 barrels in 1880 to 80,000,000 barrels in 1912 was especially rapid from 1900 on, marking a period of intense industrial activity. It made possible the completion of great en- gineering enterprises and other construction works previously out of question. One of the chief ends in those study of General Science is arousing an interest in those activities of men that are applications of science, and to learn where to go to get information concerning them which is both definite and sufficiently elementary. In the abundant limestone layers of the earth's crust the geologist reads an intensely interesting chapter of the world's history. In the rock he finds the "fossils" of shells. He recalls that shells of clams, oysters, and other marine life belonging to the division of animals known as the Mollusks, are all very largely carbonate of lime. So is the material of the great reefs and islands built by the little coral animals out of mineral matter in solution in sea-water. The chalk deposits of the southern English coast and elsewhere are of the same chemical nature, and under the magnifying glass these exhibit the remains of minute shells. The extensive 1680 IO90 1900 1910 FIG. 6 1. Growth of the cement industry in the United States". SOME CHEMISTRY OF EVERYDAY LIFE 193 deposits known as marl are an admixture of clay and carbon- ate of lime. They all give evidences of an origin in common with the material brought up by dredges from the bottom of the ocean and found to be rich in shells. It would seem that carbonate of lime in solution in sea water is appropriated by varied forms of marine life in the building of shells as external skeletons. These shells more or less broken are in time deposited along with other material on the ocean floor. As result of pressure from the material FIG. 62. Concrete construction. (Courtesy of the East Florida Railway ^ Company.) accumulating above, aided by the cementing effect of mate- rial from the water, the whole becomes a compact mass in the course of time. By reason of changes in the earth's crust these sedimentary rocks, more or less distinctly arranged in layers, may become elevated from the ocean depths even as we now find them as limestone strata of enormous extent and of great thickness. Marble is limestone rock which is somewhat crystalline, and sufficiently compact to take and retain a high polish. It is valued highly for building purposes, and in art. Marble varies greatly in color, grain, and durability by reason, possibly, of other earthy material with which the calcium carbonate is often mixed, and because of a variation in the 13 194 GENERAL SCIENCE heat and pressure to which it has been subjected. Some of the marble quarried in Italy and Greece has been famed for centuries in art because of its snowy whiteness. It has a texture well suited to the chisel of the sculptor. Great caverns are not infrequently met in the limestone strata of the earth's crust, with miles of underground pas- sages, and with vaulted chambers having huge masses of stone in the form of icicles hanging from the roof. Here on a large scale, and through long periods of time, the solvent action upon limestone of water containing carbon dioxide has been operative. The dissolved material has been carried away by underground streams. Where water containing the "lime" has evaporated in dripping from the roof, lime- stone has been left in place either as stalactites above or as stalagmites rising from the floor. These may have become joined into an ever enlarging mass that serves as a pillar to support the roof. The Mammoth Cave in Kentucky, and the Wyandotte Cave in Indiana, are notable examples in the United States of these caverns in limestone rock. Some sandstones wet with hydrochloric acid effervesce freely. If acted upon sufficiently long they are reduced to a mass of separated grains of sand by reason of the removal by the acid of the limestone cement. Such sandstone, as well as limestone itself, when used for building purposes is likely to "weather" more or less. It crumbles enough to become unsightly and a menace to the strength of walls. Carbonates of copper, of iron, of zinc, and of other metals are valuable ores. From them the respective metals are generally obtained: 1. By roasting the ore which changes it to an oxide just as limestone (CaCO 3 ) when heated yields calcium oxide ("quick-lime") and carbon dioxide as shown in the equation CaCO 3 = CaO + CO 2 . 2. By a "reduction" of these oxides of the metals to a SOME CHEMISTRY OF EVERYDAY LIFE 195 more or less pure metallic state by heating them to a high temperature along with carbon (coal, or coke) with the formation of the gases CC>2 and CO. However, the steps taken in extraction of the different metals from their ores, whether as carbonates or other compounds, vary widely owing to the character of the earthy material mixed with the metallic compound, the physical condition of the ores, and the relative expense of material and labor involved in the processes. The term limestone is often loosely used to include not only the sulphate of calcium (OaSO*) as well as the carbonate, but the carbonates and sulphates of the element magnesium (MgSC>4, and MgCOs). These latter are sometimes spoken of as magnesium limestone. The rock CaSO^H^O with more or less of earthy admixture is known as gypsum. When relatively pure it can be heated to drive off part of the water of crystallization, and then ground to form " plaster of Paris" whose uses for making plaster casts and stucco work are so well known. SUMMARY In the industrial world the varied uses of sodium carbonate, and of the numerous compounds prepared from it, make its production in enormous quantities and at a relatively low cost of utmost importance. In the Solvay process of soda manufacture, the raw material is salt, ammonia, and carbon dioxide all cheap materials. The chemical process involved is relatively a simple one, and the market price of both the carbonate and the bicarbonate in large quantities is low. When the limestone rock CaCO 3 is quarried and heated intensely hot in kilns (kils), the valuable building material known as lump or "quick" lime (CaO) is produced. This is ''slaked" by the addition of sufficient water, and the chemical change yields the finely powdered white solid CaO 2 H 2 . This when mixed with sand and water makes mortar such as used in laying walls of brick and stone. The calcium carbonate of the enormous deposits of limestone rock may be considered as once having been in solution in sea water. It 196 GENERAL SCIENCE was abstracted and built into shells by animals in tjie ocean. In due time these shells, mixed with more or less of earthy sediment from the waters, accumulated at the ocean bottom, and became compact. Marble as calcium carbonate seems to have been subjected to much heat caused, probably, by great pressure. Many of the ores of the metals are carbonates, and when these are roasted in furnaces, just as when limestone is heated in kilns, great quantities of carbon dioxide gas pass off into the air. Oxides are left. CaCO 3 is nearly insoluble in water. If there be CO 2 in the water, forming with the water carbonic acid (H 2 CO 3 ), the solution occurs much more freely. This is probably due to a change of the carbonate into the bicarbonate of calcium whose formula is H 2 Ca(CO 3 ) 2 . This dissolves much more readily than the carbonate. THE CHIEF AMONG METALS Without coal as a fuel the machinery of modern industrial life would largely stand idle. It becomes equally apparent upon reflection that without metals there would be few machines to operate, and these necessarily of the simplest type. Millions of the world's workers are engaged in operat- ing machinery in mills, factories, shops, and foundries, or in occupations dependent upon providing the raw material for this machinery and in the transportation of its finished products. Transportation by land and sea, the transaction of business, the discharge of household affairs, and the carry- ing on of agricultural pursuits without the aid of machinery would mean a return to a semi-civilized state. Something of an idea of the importance of metals in every- day life is gained through an attempt to list the articles and conveniences made impossible by a prohibition of the use of all metals. There would be no steam or gas engines, no steamships or steam and electric railways, no printing presses, no telegraph and telephone service, no suitable tools for the artisan and builder, only the rudest and most primitive of implements for farming and of conveyances in travel, no airplanes and auto trucks, no heating plants and plumbing, SOME CHEMISTRY OF EVERYDAY LIFE 197 no utensils of metal in our homes, and no builder's hardware such as screws and nails and bolts for the construction of our houses. An index of the industrial activity, enlightenment, and advance of a nation in civilization, is the extent of its metal products. It was the mineral resources of Alsace- Lorraine wrung from a defeated France in 1871 that has made this territory so valuable to Germany, and the coal and iron mines of northern France and of Belgium were an immediate objective of Germany's forces at the outbreak of the World COUHTRY Production of Iron Ore m Million 73/?j 10 to JO 40 fO 60 United States German Empire France, Great Britain Sweden Aus trig- Hungary FIG. 63. Iron ore mined in different countries in 1913. War in 1914. An enormous output in metals, together with the fuel required for their production and for marketing them as finished products, is required for industrial and commercial supremacy in world affairs. In its wide range of usefulness iron may be counted chief among the metals. In the production of iron ores the United States leads the world, and in 1913 it reached the enormous total output of sixty-two millions of tons. Its chief iron ore deposits are in the districts west and south of Lake Superior, and in northern Alabama about Birmingham. Chemically considered the metals are elements, but they commonly occur as compounds of definite chemical composi- tion, usually as oxides, sulphides, and carbonates. These compounds are mixed with rock and earthy materials, and 1 98 GENERAL SCIENCE when present in sufficient quantity to warrant profitable extraction of the metal the mixture is called an ore. Com- pounds of iron are widely distributed in soils often giving them a yellow, brown, or reddish appearance. The charac- teristic red of brick and tile is due to oxides of iron. Bricks made from clays free of iron compounds are light yellow in color. MILLION TONS 65 IG7O 1875 IBQO 1865 1390 1895 I9OO /905 I9IO 1 FIG. 64. Production of iron ore in the United States 1870 to 1914. The sulphides are perhaps the most abundant of the iron compounds but are nearly worthless as ores owing to the difficulty in completely ridding the iron from them of all sulphur, a small amount of which makes the iron brittle. Coal mined in certain districts contains iron sulphide, and when burned it gives off very offensive gases as sulphur com- pounds. Iron disulphide (FeS 2 ) as glittering yellow particles SOME CHEMISTRY OF EVERYDAY LIFE 199 scattered through sand and rocks has often been mistaken for gold, and is frequently referred to as " fool's gold." The tonnage passing through the "Soo" Canal connecting Lake Superior and Lake Huron far exceeds that through the Suez Canal, or any other of the great water ways of the world. Much of this traffic is ore from the northern Minne- FIG. 65. A freight carrier on the Great Lakes. Chamber of Commerce.) (Courtesy of Duluth sota region en route to the blast furnaces of the lake ports of Milwaukee, South Chicago, Detroit, and Cleveland, and (by rail) to Pittsburgh one of the world's greatest centres of iron and steel manufacture. Return cargoes of coal for the upper lake region swells the tonnage volume of this enormous lake traffic. The manufacture of iron and steel is so vitally connected with national life and prosperity, and a general understanding of operations involved in producing commercial iron is so readily acquired, that information concerning its sources and 200 GENERAL SCIENCE FIG. 66. Cross-section of a blast or " reduction " furnace for the making of pig iron. A, Outlet for molten iron; B, outlet for slag; C, C', inlets for hot air blast; D, outlet which conducts escaping gaseous products to ovens for heat- ing the " blast "; E, conveyor which feeds into the furnace coke, ore, and lime- stone; F, floor to lower hopper which when filled automatically dumps itself; G, counter-balance for floor of upper hopper. SOME CHEMISTRY OF EVERYDAY LIFE 201 manner of preparation for market need not wait upon a study of Chemistry. Iron is obtained from its oxides by an intense heating in "blast" furnaces of a mixture of ore, fuel (usually coke), and limestone. A reduction of the ore is accomplished by reason of the chemical combination of oxygen from the iron com- pound with carbon and carbon monoxide gas (CO) from the fuel at the high temperatures maintained day and night in the furnaces for months at a time. The supply of air re- quired to furnish the oxygen necessary for the combustion of the fuel is forced through pipes into the bottom of the furnace as a "hot blast." This air has been heated by pass- ing it through ovens kept intensely hot by burning under them gases conducted through great pipes leading out from the top of the covered furnace stack. A considerable part of these gases is CO the same gas which forms a large per- centage of illuminating gases furnished for household uses. Iron set free in a liquid form in the furnace settles to the bottom, and from time to time it is allowed to flow out into moulds made in a bed of sand, forming when solidified the "pig iron" of commerce. It contains about 5 per cent of carbon together with small amounts of sulphur, phos- phorus, silicon, and other substances. When remelted this iron can be made to take the form of any mould into which it is run, and any markings on the sides of the mould. (See page 92.) These castings when quickly cooled are brittle, but when the cooling is continued through many hours the iron becomes more or less malleable. Wrought iron is nearly pure iron, and results from burning out of molten cast iron the carbon, sulphur, phosphorus, silicon, and other substances it contains. It is tough, ductile, flexible, and malleable. Steel may be made from wrought iron by combining with it a certain small carefully calculated per cent of carbon. 1 This amount is varied somewhat accord- 202 GENERAL SCIENCE ing to the uses to be made of the steel, and the qualities desired in it. Various small proportions of nickel or of other metals are sometimes combined in steel to give it desired properties fitting it for certain uses in parts of machinery where great powers of endurance are required, or in the armor of battle ships where impenetrability without brittle- ness is necessary. The separation from the iron of the earthy material of the ore along with the ash and clinkers from the fuel is facili- tated by the use of limestone as a "flux. " In combination with sand present in the ore the calcium carbonate at the high temperature of the furnace forms a molten glass-like mass which floats as a viscid liquid above the molten iron, and when withdrawn as "slag" from the furnace from time to time it carries with it the refuse material of the furnace. The alternate layers of fuel, flux, and ore are fed at frequent intervals in at the top of the furnace stack where they are hoisted by machinery continuously in operation so long as the furnace is "in blast." The material mixed in the furnace with the fuel and ore as a flux varies in chemical nature and in amount according to the earthy constituents of the ore. Indeed, throughout the whole series of operations from the raw ores to the finished metal product exact chemical knowledge of the material used and of the changes occurring in it must be maintained. This makes possible an output of metal of any desired quality. No "guessing" at results is permissible in the industries. The exactness attained in quality of manufactured products by reason of applied chemical knowledge is strikingly seen in the fact that steel of any certain quality is sold under contract for delivery a year or more later, and before the ores or the coal for reducing them have been mined. The makers of various fabrics contract for the delivery of goods of certain desired colors before the chemicals to be used as dyes SOME CHEMISTRY OF EVERYDAY LIFE 203 have been prepared, or the cotton for the cloth has been grown, or the wool to be used has been clipped from the backs of sheep. Iron when heated softens long before it melts, and while hot can be drawn into wire or be rolled into sheets and other desired forms. In the big rolling mills steel rails for rail- roads, and the great pieces of structural iron for bridges and for the framework of big office buildings in cities, are rapidly handled and given the forms desired by means of powerful machinery in use there. The shaping of iron on the anvil of the blacksmith when hot, and the welding of iron whereby two pieces become one, is made possible by the fact that iron softens without melting as it is heated. Exposed to air and moisture iron surfaces become corroded with "rust" (iron oxide). This can be prevented by keep- ing the iron painted, or by means of a thin coating of some metal not readily affected by the atmosphere. The " tin- plate" of dealers in metals used for roofing, kitchen utensils, and dairy articles, is sheet iron which has been dipped into molten tin, a very thin coat of which adheres to the iron. The "galvanized" iron ware is sheet iron, wire, etc., which has been similarly dipped into molten zinc which forms a protective coating on the iron. By heating iron and steel to certain temperatures deter- mined by experiment and recognized by the skilled worker in metals by the color, and then cooled at a rate and in a manner likewise learned by experience, certain desired degrees of hardness, elasticity, flexibility, and tenacity may be given these metals in a process known as tempering. Edged tools of all kinds, as swords, razors, knife blades, chisels and axes must be made of tempered steel. The metal must be sufficiently hard to hold an edge when ground, but not so brittle as to break easily when hard objects are cut. It must be flexible enough to bend without breaking, 204 GENERAL SCIENCE but so elastic as to spring back at once into the original form. The hairsprings of watches are good illustrations of steel painstakingly tempered, their cost representing largely the labor expended upon them. Spring balances of tempered metal are used for weighing, and comfort in travel is made greater by the steel springs under the wagon or auto body and underneath the railway car. The character of the work of "The Village Blacksmith" has materially changed during the past fifty years, machine work in metals having now largely replaced hand labor. However, the increase in dependence of mankind upon the use of metals in that time for comfort and well-being has been little short of marvelous. In extent of use, and in the changes wrought by such uses in the affairs of men and of the world at large, iron and steel rank chief among the metals. SUMMARY The industrial activity and commercial supremacy of an enlightened nation is intimately related to its national resources in metals, and in coal supplies for the development of these resources. By reason of the enormous quantities of iron employed in the arts and industries, and because of properties which adapt it to innumerable uses, iron ranks first among the metals in usefulness. The metals are chemical elements. An ore is a mixture of rock or other earthy material with some compound of a metal present in suffi- cient quantity to make its extraction profitable. The "pig iron" of commerce is a product of the "blast" or "reduc- tion" furnace where the iron ore as an oxide gives up its oxygen to combine with the intensely heated carbon of coke or coal. Castings of iron and steel of excellent design are possible by reason of their expansion as they solidify. Metals very generally shrink in volume as they change from the molten to the solid state. Gold and silver coins have designs and lettering stamped upon their surfaces under pressure of powerful machinery. Mixtures of various metals in a molten state and in certain proportions are known as alloys. Some of these, such as type-metal and various kinds of "bronze", are suc- cessfully moulded due to their expansion when solidifying. SOME CHEMISTRY OF EVERYDAY LIFE 205 Steel in general is iron containing somewhat more carbon than wrought iron but less than cast iron, the per cent varying according to the uses to be made of the steel and the properties it necessarily must have. The "tempering" of steel by workmen skilled in the art through experience consists primarily in securing a desired degree of flexibility, elasticity, tenacity, and hardness. These properties are varied by the extent and rate of temperature changes ta which the metal, and the cohesive force acting between its molecules, is subjected. X. AT OUR HOMES ROOMS OF THE HOUSE," THEIR FURNISHINGS, AND THE COST or LIVING A good home, together with all the comforts and influences and associations that should centre in it, is essential to the largest degree of happiness in life. However costly the dwelling that shelters a family, it may be anything but a true home by reason of the manner of life of the people who inhabit it. On the other hand the best of human affections and influences may centre in the rudest of structures. Yet it remains true that comfortable and well-appointed dwellings constitute a large factor in having good homes. To possess a good home and good home surroundings, though these be moderate in cost, is worthy the ambition and sustained effort of any American citizen, man or woman. It is the testimony of close observers that people of limited means and scant resources are very commonly the ones who fail to get the full worth from every dollar spent for home comforts and for family support. Lack of understanding of what to get as appointments for the home, and of what should constitute a suitable original outlay for them and a reasonable period of service from them, results oftentimes in deplorable waste and unnecessary deprivation. There is ample opportunity for the exercise of individual tastes and preferences after standards have been established concerning what is desirable for the comforts and conveniences of modern family life. These standards may be upon any scale desired for the persons whose interests are to be served. 206 AT OUR HOMES 207 Public schools are maintained to make possible higher ideals and larger attainments to those who avail themselves of school advantages.. Discussion of whatever contributes in any large degree to better living has an important place, in the school curriculum. Courses in Home Economicsjean and should give instruction in schools calculated to lessen waste in American home life, and to increase its comforts and FIG. 67. A modern farm kitchen. general welfare. Here as in other school activities advantage should be taken of the knowledge gained through home experiences. These, along with the instruction given in schools, may be so organized as to uplift and improve life in the home. Wise expenditure of a family income, and an efficient household management, requires scarcely less of business and administrative ability than does the conduct of enterprises outside the home. Efficiency counts not less here than in 208 GENERAL SCIENCE the business world, and to this end both husband and wife contribute in the discharge of all duties assumed by them or naturally devolving upon them as individuals. The arrange- ment of rooms in the house, and the furnishings that best contribute to the conduct of household affairs, together with all matters connected with the cost of living, are of joint concern to all members of the family. So great have been the changes within the last half century in conditions of family life, and in the kind of work necessary in household affairs, that plans of houses built to-day differ widely from those of two generations ago. This is true in many respects other than "modern con- veniences". Then the kitchen was the centre of all the manifold activities of the home life. As a veritable "living room" it was made sufficiently large for use as dining room, laundry, and sitting room, and for the preparation of food- stuffs for both immediate and later family use. Nowadays it is often a model in its compact arrangements and con- veniences for work. It is so planned as to economize both time and energy in the discharge of the fewer household duties that centre in the kitchen. Before moving into any dwelling it is a matter of wise precaution to gain some knowledge of its history with regard to infectious diseases. The possibilities of disease germs remaining lodged on its walls and woodwork, or in corners and cracks where dirt has accumulated, is sufficient reason for care in this respect. Paint and varnish and new wall paper have values other than for cleanliness and improved appearances. Since sunlight and fresh air are destructive of disease germs, and dampness is conducive to their development, all rooms in a dwelling should be light, airy, and dry. Win- dows are to let in sunlight and air as well as to keep out dust and cold. From time to time the furnishings of rooms AT OUR HOMES . 2 09 should not only be dusted out of doors, but be exposed as well to wind and sun. The basement should be dry and well lighted, and thoroughly ventilated. Its floors and walls and foundations should be so constructed as not to harbor rats, mice, or vermin of any sort. The experiences of the human race long ago established the fact that cleanliness in person and in the home not only contributes to comfort and civilization, but is essential to health and well-being. Boiling hot water for laundry uses, for washing dishes, and for general household affairs, is a most effective disinfectant, and the free use of soap contributes to the same end. Any consideration of the cost of living naturally has much to do with food and clothing. Discussions in school of food values and prices, supplementing home experiences, very properly may emphasize the fact that there is often great waste in the purchase of food supplies both in their quality and in the quantity secured for the outlay made. The choice of a wholesome and balanced diet is an important topic of instruction in schools. Ignorance in this respect usually results both in malnutrition and in thriftless living. The wide variation in food values secured by different people in return for the same outlay makes necessary some elementary instruction in schools concerning the purchase and preparation of foods. It is a matter of general good health and well-being. Cheap cuts of meat, for instance, may contain when properly cooked as much nourishment as those more expensive. To substitute less expensive foods for the more expensive ones, when the former furnish just as much food value, is not only thrift but good common sense. The practice of doing without tea and coffee is not only a matter of economy, but it has the greater purpose of promoting health. Neither tea nor coffee has any food value, and other drinks may be provided that are free from the harmful effects of caffeine. 14 2IO GENERAL SCIENCE To choose habitually what really ministers in largest .measure to one's welfare in matters of food, clothing, amuse- ments, and self-indulgence necessitates a knowledge of the experiences and teachings of others. This knowledge may be gained at home and at school, from books and from people. In general it is a reasonable statement that any girl's edu- FIG. 68. Canning as a home occupation. cation is incomplete without some definite personal acquaint- ance with the affairs of a household, and some degree of proficiency in their management. And in no less degree, though in different relationships, every boy's education should include an intimate knowledge of the needs of a household, and how these can be supplied within the limits of a moderate income. Fortunately the cost of a simple rational manner of living is relatively low under normal conditions. It is not only AT OUR HOMES 211 relatively inexpensive as a rule, but it contributes largely to the very best things in life. To learn this by experience only may be to repeat the mistakes of others rather than profit by them. Thriftlessness leads to poverty with all its limi- tations upon comfort and well-being. To become capable of earning a sufficient income, and to be intelligent in its ex- penditure, usually involves long-continued and well-directed effort and much self-denial. Without the advantages of attendance upon school the wage earner is always at a great disadvantage, and the most desirable positions of service, power, and profit are often unattainable to those lacking in education. The personal characteristics of thrift, industry, business integrity, and right conduct in all things are, however, not dependent upon schooling. The cost of right living demands both a knowl- edge of what is best for one, and a willingness to do what is best. Self-restraint is necessary in one's life to assure its efficiency, and to avoid wasting life's opportunities and possibilities. There is always a sharp line of distinction to be drawn between outlays in life that are necessary because of the better conditions of living that result from them, and those other outlays which though desirable are not in any sense indispensable. No community can afford to be content with a contaminated water supply whatever the cost involved in safe-guarding it. No individual or family can afford to inhabit a dwelling in the basement of which water always stands, whatever may be the expense of drains and water- proof foundations. On the other hand outlays for what merely gratifies expensive tastes and habits are always ques- tionable. The use of tobacco may very properly be chal- lenged on the ground of its being a useless expenditure, as well as on the more serious charge of its being a menace to the physical and mental development of boys and young men. 212 GENERAL SCIENCE Generally speaking nothing in life costs too much if there is ample return in well-being for the individual himself or for others. To attain the best things in the lives of individuals requires as a rule long-sustained efforts and sacrifices. There is doubtful value in any lesson that has required no effort, and in any education or in any fortune for which labor and sacrifice have not been given. There is no other one item in the nation's bill of expendi- tures so appalling in its economic waste as that for alcoholic drink. Increased taxation is necessary to care for those whose lives have been wrecked by it directly and indirectly. The consumer gets nothing in exchange for his outlays that ministers to his well-being, and it lessens his efficiency as a worker and undermines his thrift. SUMMARY Unwise expenditures in living expenses are a common accompaniment of poverty, and often a direct cause for it. Lack of intelligence in buying largely increases the cost of living for those who have abundant means; for those of limited resources, it usually results in getting far less for their outlays than they should. Any proper valuation of articles purchased takes into account not only the original outlay for them as cost price, but their probable length of service, and whether or not they are well suited for their intended uses. This is especially true in the purchase of clothing, and when buying a house and household furnishings. Business ability, and an executive skill of high order, is required for an efficient household administration. In spending wisely the part of a family income set aside for family expenses, the wife and mother becomes as truly a supporter of the family as the husband and father. Instruction at school in household management, based upon home experiences and applied to the betterment! of the home life, constitutes an important service rendered by the public schools. Public school instruction in the elements of home economics is a means for bettering individual welfare and improving social conditions. Health and self-respect alike demand that families be well housed. In congested centres of population the high cost of dwelling places, AT OUR HOMES 213 whether to own or to rent, constitutes an increasingly difficult problem in living. t Ignorance in the choice of a suitable diet for a family, and for an individual, is not only thriftless but it commonly results in malnutrition, ill health, and shortened lives. The well-to-do are perhaps as often victims of this failure to regulate diet as are those handicapped by poverty. Any rational manner of life takes account of whatever ministers to the comfort, happiness, and welfare of individuals and of communities. It seeks the highest efficiency in right living, and avoids whatever is merely self-indulgence. A simple life is quite consistent with a high order of living and in a measure is indispensable to it. It is to be remembered that in changes of styles in clothing there is involved the financial gain of those who seek to market a new stock of goods. It is not fundamental to well-ordered living to discard cloth- ing of any sort while it is yet suitable and serviceable merely for the sake of changing to something new. Exercises 1. Who usually determines the selection of things needed in a household, both as regards their quality and the prices paid for them? 2. In what sense is the wife in a home, though not a wage-earner, as truly a supporter of the family as the husband? 3. Distinguish between, (a) waste and thrift; (ft) necessities of life and its luxuries; (c} comforts in living and extravagances. What factor very largely determines in which of these classes an outlay by any person or family shall be put? 4. What advantages may there be in cooking breakfast cereals the day before rather than on the morning of their use? 6. Where gas is used in cooking, or for laundry purposes, why is it wasteful not to turn the gas low as soon as the wash water or food begins to boil? 6. What precautions should be observed in the purchase of fruits other than securing honest measure and fair prices? What further precautions are necessary before use of these fruits as food? 7. Aside from a garden, name various ways of reducing expenditures for foods without sacrifice of proper quantity and wholesome quality. 8. In what ways is there relation between the high cost of living and follow- ing the fashions in dress? 9. To what extent are "styles" in clothing properly followed? 10. Give some arguments for the outlay involved in the maintenance (a) of free public schools; (6) of churches as places of public worship. 11. What is a wise rule to follow in the matter of outlays for amusements? 214 GENERAL SCIENCE 12. As an important item in the cost of living, what are some of the argu- ments advanced to warrant a system of insurance against fire, accidents, death, and disabilities from old age? 13. What may be used to clean sinks and bath-tubs of the "scum" from hard water? 14. What is the nature (a) of paint; (6) of varnish? Aside from any improve- ment in appearance, why should woodwork be painted if it is to be exposed to the weather? Why have furniture and woodwork indoors varnished? 15. What in general should characterize the furnishings of a home? 16. State the value of a basement for a house aside from the extra room it affords. FUEL AND LIGHTS FOR MODERN HOMES Possibly in no one respect are the comforts of modern life more fully manifest than in the heating and lighting of American homes. Whittier in "Snow Bound" pictures for us a winter's evening in a New England home of the first half of the nineteenth century: "Shut in from all the world without, We sat the clean-winged hearth about, Content to let the north wind roar In baffled rage at pane and door, While the red logs before us beat The frost line back with tropic heat; And ever when a louder blast Shook beam and rafter as it passed, The merrier up its roaring draught The great throat of the chimney laughed." However, we should not overlook the fact that all other rooms in this typical farm home were probably icy cold, and that with all the lavish use of wood as fuel in the big-throated fireplace, costing as it did little more than the labor incident to cutting and hauling it, there was none of the comfort enjoyed by us in the even temperatures so easily maintained in all parts of our present-day homes. AT OUR HOMES 215 The poet in his later years could well forget that in the big living room of his boyhood days, with face burning from the heat of the open fire, there was scarcely a place where his feet at the same time were not chilled in the rush along the floor of cold air from every doorway crack to feed the chimney's draft. In memories of the "Dear home faces whereupon the fitful firelight paled and shone" the hard- ships incident to a winter's cold in the homes of those early days were doubtless forgotten. FIG. 69. Birthplace of Elias Howe, inventor of the sewing machine. In time the woodlands were largely cleared for cultivation, the trees it may be having been burned just to get rid of them- The old-fashioned fireplace was closed. More and more generally from about 1830 onward stoves began to come into use as heaters and for cooking purposes. Coal as a fuel was discovered in Pennsylvania about 1820. The rapid increase in amounts used for industrial purposes, however, dates from about 1880. The production and distribution of the enormous amounts 2l6 GENERAL SCIENCE of coal now required in the United States at prices which on the one hand shall not affect disastrously the varied indus- tries of the country dependent upon steam power, and* on the other the comfort of the people in their home life, con- stitutes a "fuel problem" likely to continue till the natural resources of the country in its coal deposits shall have become exhausted. nil lion Tons 500 JOO 00 IOO \l\l\\\\\ FIG. 70. Production of coal in the United States 1830 to 1910. Without coal as a fuel, and without any available substi- tute for it in ample quantity, practically all the machinery of modern life must come to a standstill. Factories, shops, mills, furnaces, together with railway and steamship lines, cannot be operated on the same scale as now. Commerce, transportation, and manufactures will return to the lower volume of an earlier age, and present-day standards of living will likewise be lowered. That this may not come to pass other motive power than steam more and more must come into use. Coal as dug from the earth is carbon in varying per cent of purity. Its structure gives ample evidence of its being the AT OUR HOMES 217 remains of plant growths. The coal age in the earth's his- tory as given in Geology must have been a time when climatic conditions were unlike those of the present day. Vegetation grew rank in an atmosphere warm, and laden with moisture and carbon dioxide. During long periods of time accumula- tions of woody material of great thickness must have been kept from decay by submergence in the waters of marshy regions. Under the pressure of layers of earthy material washed in upon it, this vegetable matter largely shut away from the air became changed in course of time into the varied forms with which we are familiar as coal. The several layers (" veins") of coal, separated by layers of slate or other rock material, represent successive periods of accumulation and of submergence. Through later periods, and probably when vegetation did not flourish so luxuriantly, these thicknesses of vegetable matter became buried in the depths where as coal they are now found. It should be mentioned here that all this carbon represents " stored solar energy'' used by plants in the separation of the carbon from the carbon dioxide of the air. Enormously long periods of time must have been involved in this forma- tion of the coal layers so nearly indispensable to the welfare of mankind. It is calculated that at the present rate of increase in the production and use of coal the world's supply will become exhausted in somewhat more than a hundred years. Long before then, however, unless other forms of energy are employed for doing the world's work, the rise in prices due to a limited supply is likely to make them prohibi- tive for most people. All means for illumination in common use in homes depend upon the fact that when the temperature of a substance has been raised sufficiently high it becomes incandescent, i.e., it gives out light. In candle, kerosene lamp, and illuminating gas flames the carbon particles present in the gas or vapor 218 GENERAL SCIENCE are made incandescent by the heat of combustion as the vapors and gases burn. In the incandescent and arc electric lights the incandescence is caused by electrical energy being transformed into heat. Much resistance is offered to the passage of the electricity in the filaments of one, and through the air gap separating the carbon pencils of the other. The intimate relationship believed to exist between heat and light as forms of energy is shown in the explanation that as the temperature of a body rises by reason of increase of its molecular activity there comes a time when the ether dis- turbances originating in the quickened movements of its molecules, and radiating outward from the body in straight lines in every direction, become sufficiently frequent per second to affect the optic nerves in our eyes, resulting in a sensation of light and enabling us "to see." Bodies from which these light waves originate are said to be luminous. Most bodies about us are non-luminous, and we see them only because light coming to them is reflected to us and into our eyes. Much of the expense of artificial lighting systems lies in the fact that there is large waste involved in production of the heat necessary to incandescence. Illumination by "cold light," i.e., at temperatures as low as that of the light emitted by fireflies, would greatly increase the comfort and cheapen the cost of household illumination. SUMMARY The plumbing, heating, and lighting of modern American homes exhibits in a striking way the contributions of scientific achievement and inventive genius to the comfort and well-being of this generation. The homes of our grandparents, and the palaces of kings a century ago, lacked these things. What we now consider necessary to our well-being they had not dreamed of. Coal like the other natural resources of timber, ores, petroleum, and natural gas, is not exhaustless in quantity. As a source of power by reason of the heat liberated when it is burned, coal is at present indis- AT OUR HOMES 219 pensable in the industries and in commerce. The heat liberated from it may be considered solar energy stored during the centuries of a remote past. It was not till about 1880 that the "incandescent" light with its carbon filaments within an exhausted glass bulb, perfected by Thomas A. Edison (1847 )> became a commercial success. The extended use of the powerful arc lights for out-of-door illumination waited upon the development of the dynamo to maintain sufficient strength of current through long periods of time at relatively low cost. SOME FOODSTUFFS There is much more to any consideration of what one shall eat and what one shall drink than is involved in its market price as part of the cost of living, and its purity and whole- someness as these affect one's health. How much to eat (or how little), and the relative amounts of the different foods 1 in order to give a balanced ration, are too often given scant attention till ill-health and its limitations make orders from the physician imperative. A person's appetite naturally is not only nature's warning of need- for food by the body, but under normal conditions it should serve as a guide in choice of the foods best suited to meet these body needs. That which is appetizing, and for which one has great relish, is in general good for one. Unfortunately the appetite may become perverted or dulled, and its guidance alone is always unsafe. The use of any food or drink that creates a craving, and which demands more and more use of it (any " habit- forming " substance), is always to be shunned. One should never eat beyond his ability to fully digest what is eaten. Any meal is sufficient 1 The term food as used here and later is to be distinguished from "food- stuffs" as sold in the market, and the various " dishes" served at table for our meals. It has reference to the groups of chemical compounds named on page 222. 22O GENERAL SCIENCE where one can work to the next meal time without becoming exhausted in strength or ravenous in appetite. When people are well any lack of appetite should generally mean absence of bodily need for food. As a rule it is better to stop eating, especially when the meal has been at all hurried, before being quite fully satisfied in hunger. <. vo ?\> v>i f production on the eastern farm. Cattle fattened in the far West were slaughtered at Kansas City, Omaha, or 284 GENERAL SCIENCE Chicago, and the meat shipped to eastern towns for sale at prices as low as the cost of production there. Any simple statement of changes in the life of the nation due to these causes, and to an annual immigration, often exceeding a million a year, is not broad enough. Any dis- cussion of the economic conditions involved in these changes in production, trade, and industry, and any discussion of the geographical conditions that have directed and modified these new currents of national life, is incomplete in itself. Underlying it all, and interwoven with all this progress to- ward more of the comforts and conveniences in life and less of its hardships, is a degree of scientific achievement that is marvelous. In its applied form, as translated into terms of machinery, science has multiplied the working capacity of individuals in many cases a thousand fold, and has shifted the burden of large parts of the world's labor from man to machines. Inventive genius, applying the results of scien- tific discoveries, has perfected machines that demand workers of the highest intelligence to operate and care for them. Unskilled labor is ever put more and more at a disadvantage in this scientific age. A striking illustration of development of natural resources under stimulus of applied science and invention, and of a revolution wrought in the social, agricultural, and industrial life of the United States in connection with such development, is seen in the widespread use of automobiles, motor trucks, and gasoline-driven machinery of all kinds. Man's mastery of the air waited upon the development of light but powerful engines using petroleum oils for fuel. It was necessary that these heavier-than-air machines be given a velocity not only sufficient to sustain themselves, but to make long flights possi- ble even when carrying passengers or other load. Marvelous as was the rapidity in introduction and use of gasoline machinery for factory, farm, and highway, the development CONDITIONS AFFECTING INDUSTRIAL LIFE 285 FIG. 90. Interior of a silk mill. (By Underwood and Underwood.) 2 86 GENERAL SCIENCE of aerial navigation under stress of a world war, and its as- sured usefulness in times of peace, is occasion for even greater wonder. Petroleum as obtained from deeply drilled wells is a heavy liquid of a characteristic disagreeable odor, and often times is greenish in color. The rise of the petroleum industry in the United States dates from wells driven in 1859 near Million Barrels zio zoo 190 IOQ no /BO ISO 140 I3O HO no too 90 00 70 60 50 40 JO ZO 10 / / I / / / ^ / / / / / ^ / v^ Jr / ^^ / ^^ ^ **^ ^-- ^ r ..*-- -. - *>^* \\ * M B 2 n D C 5 v c o ? g :> x * -i i S -1 C '; \ 3 5 o a \\ | 5 < 1 3 ' n M n u n ii S i (i \\ n j FIG. 91. Production of petroleum in the United States from 1860 to 1910. Titusville, Pa. The accompanying graph shows the rapid increase in its production in this country. For years kero- sene was one of the most important products of the refining of petroleum. Its use in lamps for household illumination became world-wide. Knowledge of the importance of numerous other products from the refining of petroleum, and of the manner of their separation from one another, may be gained in the study of Chemistry. Among these products CONDITIONS AFFECTING INDUSTRIAL LIFE 287 are the aniline dyes, and long lists of substances handled in the drug trade. The oil fields of Indiana were opened in 1897, of Texas in 1901, of California in 1903, and of Oklahoma in 1905. The petroleum from the Texas and California fields has extensive use as fuel supply for shipping and for locomotives in rail- way service. So important is an ample supply of petroleum FIG. 92. Location of the larger oil fields of the United States. for the navies of the world and for shipping generally that all large sources of its supply, including on this continent the rich oil fields of Mexico, are subjects of greatest concern in international relationships. From the development of the petroleum industry in the United States has come great added wealth to the nation as a whole. But it has concentrated vast fortunes in the hands of a few individuals, and has given rise to business organizations exercising far-reaching influences in trade and commerce, and in the social and economic conditions affecting the lives of people generally. As in the case of coal with which it is so closely related in chemical nature and geological 288 GENERAL SCIENCE history, petroleum is a natural resource limited in amount. Its restricted production and possible exhaustion may reason- ably be forecasted. The use of farm machinery when operated by horses has more than doubled the area of farm land that one man can cultivate. Because of the wide use of farm machinery not as many men are needed in the farming districts. Farms which were sufficiently large when labor was done by hand have proven unprofitable when expensive machinery is employed. Abandoned farm buildings are not infrequently seen in many sections of the United States, bearing witness to a readjustment of rural conditions inevitable, perhaps, but not altogether satisfactory. In many sections there has been a marked increase in the size of farms, and a decrease in the number of families living on them. The standards of living during this time underwent change. People demanded more of the comforts of life in their homes, and less of the hardships and the drudgery endured by the forefathers in an undeveloped new country. Farms that had supported successive generations of prosperous American country-folk were declared to be no longer desirable places of residence. Better schools were provided for children in the towns. There was the possibility in towns and cities of steady employment in office, store, shop, mill, or factory for women as well as men. An income from wages was not subject to losses by bad weather and crop failures. All these conditions, together with the various advantages that town life offered in other ways, contributed to a phenomenal drift in population from the farms to the cities, especially in the eastern portion of the United States 1 . There was a radical 1 The Census Reports of the United States by decades show the percentage of the population of the country resident in cities and towns of 2500 or more inhabitants as follows: 1880 1890 1900 1910 29 . 5 per cent 36 . i per cent 40 . 5 per cent 46 . 3 per cent CONDITIONS AFFECTING INDUSTRIAL LIFE 289 change in the character of the rural population and of rural life generally over widespread areas. SUMMARY ' The relationship is very close between the geography of any region, the occupations of its people, and their advancement in trade, industry, and civilization. As the population of a country becomes more dense, complex ques- tions arise affecting transportation, cost of living, and employment of labor. There must be adjustments of government to varied interests that are more or less conflicting. Some knowledge of the college sub- jects of Economics and of Sociology becomes highly desirable. But one does not have to make a study of these branches in order to understand a great deal about the mutual dependence of the people of different sections of any country, and of the people of all parts of the world. Within the half century following the Civil War a marvelous develop- ment occurred in the United States affecting its industries, population, wealth, and the manner of life of its people. The history of this period will strongly emphasize the development of natural resources that took place, and the extensive changes and readjustment of conditions that occurred, incident to the introduction and use of machinery. An understanding of these changes in the life of the American people is impossible without a knowledge of the scientific achievements of this period, and of the years just preceding it. Exercises 1. Mention some of the differences involved in making a living by business or professional life, and by working at a trade. 2. What general relationship exists between transportation facilities and the size of towns? 3. What very largely affects the choice of location and the development of any particular manufacturing industry? 4. What are the serious disadvantages to any country in having its industries centralized rather than widely distributed? 5. Give some of the principal reasons why people move into towns and cities to live. What are some of the decided advantages of life in rural districts? 6. What conditions affecting the workers in mill, factory, or shop correspond to the uncertain returns from farming? 19 2 go GENERAL SCIENCE 7. If an annual inventory be made by the wage earner and by the farmer, even as by the business man, what in each case would constitute a showing of profits? 8. Upon what besides taxable property does the wealth of any community depend? SOCIAL AND ECONOMIC CONDITIONS AFFECTING THE WAGE EARNER Incident to the rapidity with which changes in industrial life have been brought about in this country have come many FIG. 93. Thriftlessness and poverty. evils. Enlightened citizenship demands that provision be made for sanitary conditions of life everywhere, especially in the over-crowded sections of great cities. Ordinary prudence demands such thrift that when periods of depres- sion come to the business and industrial world, even as crop failures come to the farmer, no extreme poverty and distress will be experienced. Poverty is a common accompaniment CONDITIONS AFFECTING INDUSTRIAL LIFE 291 of thriftlessness and inefficiency, and freedom for many hours a day from all demands of labor is not necessarily conducive to better living. We wonder at statements made by competent authorities that four millions of people in this country are dependent upon charity, public or private, and that ten millions more are underfed and handicapped in life because of the condi- tions under which they live. Much can be done to remedy these conditions by means of public enlightenment and far-reaching economic legislation. The individual himself, however, is always responsible for making the most of all opportunities for self -betterment, and for avoiding whatever wastes his time, means, and health 1 . x The following are the "Financial Life Records" of one hundred average men who at twenty-five are healthy, vigorous, of good mental and physical capacity, and without means of support other than their own ability and efforts, as shown in data compiled and published by the Savings Bank Sec- tion of the American Bankers Association: At the age of 25 35 45 55 65 75 Dead 5" 16 20 g 6* Wealthy 10 2 i C 2 In good circumstances IO 2 In moderate circumstances Those without financial means ... 100 Not self-supporting 40 35 65 16 46 30 6 53 34 IOO IOO IOO IOO IOO IOO Of the sixty-three dead at seventy-five years of age, sixty left no estate (property of value sufficient for matter of record). Those listed as not self- supporting were more or less dependent upon children, relatives, or charity. Records of Surrogate's Courts show that for every 100 men who die the estates of three are $10,000 or above; of fifteen are from $2,000 to $10,000; of eighty-two are of no considerable value. Of every 100 widows eighteen are left in comfortable circumstances; forty-seven are obliged to go out to work for a living; and thirty-five are left dependent, or in want. In 1914 in the United States there was spent for tobacco 520 millions of dollars, and for alcoholic beverages 1720 millions of dollars. 292 GENERAL SCIENCE The hours of freedom from labor, both of men and of women, should yield rest and refreshment and intellectual advancement, and not be spent in ways that dissipate money, time, energy, or ability. The thrifty farmer a half century ago was astir at five o'clock in the morning, and abed at eight o'clock at night. Few if any of these intervening FIG. 94. Benjamin Franklin hours had been used for anything other than labor for the family welfare. The hours of a day's labor for the housewife were even longer. The vigor and vitality, the worth and excellence of these people, made possible the conditions of life that we enjoy. Right use of the time and energy secured by a release from the drudgery of life means a higher civiliza- tion, and larger individual happiness; its wrong use may mean degradation for the individual, and destruction to society. One great purpose of attendance upon schools is to learn CONDITIONS AFFECTING INDUSTRIAL LIFE 293 what are wise courses to follow in life, and how most advanta- geously to use the accumulated knowledge of mankind. The lessons of chief importance in school and home alike are those that teach the wisdom of the ages concerning human conduct that knowledge which the later experiences of life only verify and emphasize. Any education is faulty and incomplete which does not include instruction and practice in those ways of life often referred to as its " virtues" 1 . These cannot be fully taught or sufficiently practised in school alone. Maxims such as are named below characterize a well-ordered life. They are applicable to all individuals in all the walks of life: Avoid those indulgences that lead one to live beyond his means. Choose those pleasures in life which are healthful, and which cost little in money and effort. Abhor waste of any kind waste of strength, or time, or means. Remember that one's savings rather than his income measures his increase in wealth, and that more wisdom is necessary to spend wisely than to save. Choose that kind of an education which shall aid in living a more efficient and wisely ordered life. The worth of an education to anyone is largely meas- ured by what kind of a person it helps him to become, and by what he is en- abled to accomplish because of it. Make no exchange of health for pleasure, wealth, or position. He who makes so bad a bargain finds his attainment worthless for lack of health. Avoid any conduct, any business practice, any traffic legal or illegal, that advances the interests of one person or class at the expense of another, and results in harm to others rather than their good 2 . " Sayings" such as these sum up invaluable experiences of mankind. They correspond to the truths or " facts" 1 Every generation of American boys and girls should become familiar with the form and significance of some of the sayings of Benjamin Franklin statesman, publicist and scientist. Some of his "wisdom" as it affected American home life of earlier generations may be found in "Poor Richard's Almanac". (Houghton, Mifnin Company: Boston. Paper, fifteen cents.) 2 Such courses may be classed as criminal in character whether as a business, trade, or practice. However, there is need to distinguish carefully between practices fundamentally criminal, though often legalized, and the person engaged in them who may be innocent of any criminal intent. 294 GENERAL SCIENCE upon which the scientist must base his theories, and the various other facts which business and professional men take into consideration in formulating their procedure in the affairs of life. It is as necessary to take them into account in one's manner of living as it is for the scientist to take account of the facts that affect his theories and his practice. To ignore the realities of human existence, and to fail to adjust conduct to them, is as if the scientist failed to make his theories fit the facts to which they relate. There should be direct relationship between the training of the laboratory in high school science, and a preparation for those activities in which one may engage later in life. This relationship can be wholly apart from any skill acquired in handling apparatus and machines. In the affairs of life, as in the laboratory and study room at school, the particular difficulty or "problem" that demands attention at any time requires ability to get the facts bearing upon it, and ability to discriminate in the relative importance of these facts. It is necessary to decide, too, the course to be pursued in view of one's understanding of the facts so that labor of hand and head shall count most. When any such plan of action fails to give the results desired, then there must be ability and willingness to review the whole situation, to correct errors in fact and in judgment, and to undertake anew the application of the changed plan. This in a simple way is the procedure of the scientist in making advances in learning. It is the course pursued by successful business and professional men, and it is a course which begun in school may be continued throughout life. It is to be remem- bered that one's school days are but a beginning in becoming educated. No acquaintanceship with books and their stores of human learning is a substitute for industry. Health and efficiency at- tend upon the combined exercise of body and brain. Habits CONDITIONS AFFECTING INDUSTRIAL LIFE 295 of industry like other habits, and correct notions of the dig- nity of labor, are largely formed in childhood and youth. Idleness too commonly leads to vice, and the energies of youth demand a healthful outlet in employments suited to age and strength. To expect a boy or girl to grow up in idleness and without responsibilities till sixteen years of age or thereabouts, and then at once to become a steady efficient worker, is to ignore human experience and the power of habit. SUMMARY No nation can be considered truly prosperous, and no social condi- tions are satisfactory, where everyone regardless of occupation may not have wholesome surroundings of life if they will, together with ample provisions to safeguard health and life. Perhaps at no time in the world's history have its workers who are industrious and thrifty been able to possess so much that contributes to comfort and well-being as now. To this condition scientific achieve- ment has contributed largely, putting within reach of those of moderate means what in former times was available to few if to any. Many of the comforts and conveniences and furnishings of an unpretentious modern home were unknown less than a century ago. The large use of machinery for doing the work of the world has con- tributed to lessening the hours of labor, and doing away with much of life's drudgery. Whether work is a curse or a blessing to individuals, and to people generally, depends upon whether or not it uplifts them in physical, intellectual, and moral well-being. Freedom from labor, and many hours of leisure because of shortened hours of labor, must be judged in the same way. The same rule, too, can be applied rigorously to those who because of the possession of wealth find it unnecessary to labor for a livlihood. Advances in civilization, and improvement in the life of any indi- vidual, depend in large measure upon avoiding the mistakes of those who have learned by experience. It is foolish not to be guided by what others have learned. One of the chief purposes of schools is to bring this knowledge before the pupils of each generation for their benefit and use. 296 GENERAL SCIENCE There are ways of acquiring and applying knowledge that are pecu- liarly scientific, and not least of the worth of a training in science studies is a "scientific attitude" of mind toward all the affairs in life. One of its characteristics is in basing opinions upon facts only, and in testing out these opinions to see that they are in accord with facts. This requires ability to collect and associate all available information gained from personal experiences, from experimental work, and from books. Conclusions thus reached may be followed in any of the affairs of life with reasonable assurance of success. XIII. THE FARM POULTRY AND EGGS One of the noticeable differences between meat from the hen, and that from wild fowls generally, is its color. The domesticated fowl has a large amount of white meat as result of less use of the muscles, and a consequent lessened supply of blood to them. This is especially true of the muscles of the breast which are used in flying. The great weight of the domesticated hen makes flight for any considerable distances impossible. The same thing is largely true of domestic turkeys, geese, and ducks. The bone structure of the domesticated fowls is denser and stronger in order to support the heavier weight of body. The mounted skeletons of birds of flight, such as the various songbirds, show when examined a remarkably light structure, the bones commonly being hollow. The quill feathers, too, strong but light, show a wonderful adaptation for use in flying. The hen walks on her toes which terminate in nails (claws) very serviceable in scratching for food. The scaly and more or less featherless part of the leg corresponds to the human foot. Through it pass tendons that move the toes. The muscles of the _" drumstick" from which these tendons arise exhibit in their color and development the great use the hen makes of her feet. The drumsticks correspond to that part of the human leg from knee to ankle, while the thigh bones of a fowl are closely joined to its body and are covered by the body skin. 297 298 GENERAL SCIENCE The wings correspond to the arms of people, and both upper and lower arm bones are coveredfby the skin of the body. Imagine a person with the whole length of arm to the wrist doubled upon itself and tied close down against the body, and the fingers and hand covered with feathers. Then consider the difficulties experienced in efforts to feed one's self and to keep clean. The neck structure in fowls gives a wonderful variety in movements and in serviceable- ness, securing both strength and flexibility. One use of the bill (beak) by birds and fowls is in keeping their feathers clean and in place. The leg structure of birds that perch (roost) is such that the weight of the body causes the toes and claws so to grasp the support that when asleep they cannot fall off. Dif- ferences in the kinds of domestic fowls due to breeding is a matter of importance to poultrymen. When combined with the care of the home garden, the responsibility associated with the keeping of poultry provides for both boys and girls an educational training at home as valuable as any " course" in schools. There is an abundance of literature of great worth upon both Gardening and Poultry Raising, much of which may be had at slight outlay. But the educational .value of these occupations for boys and girls lies in the initiative, the persistence, and the good judgment demanded by the home work. It combines physical and mental effort in a manner similar to that which characterizes advancement in first-hand study of the sciences, and success in the affairs of life generally. Agriculture as a school subject needs application of its teachings even as does Home Economics. It may be secured in part at least through the care at home of a flock of fowls, and of the vegetables in the garden. This is in addition to caring for the lawn, the fruit and flowers, the trees and shrub- bery about the home. Along with the increase in skill and THE FARM 299 ability in this work there should be developed business habits and enterprise quite as valuable as that gained in other life experiences. Both poultry raising and gardening have become highly developed industries in many localities. This is especially true in the vicinity of cities that afford good markets. In both fields of effort capital, executive ability, and a clear understanding of the conditions and details of the business, are necessary to success. The value of the egg production FIG. 95. Feeding the flock. in the United States amounts to millions of dollars annually. This seemingly negligible source of national wealth is an item of importance in the cost of living and in the wholesomeness of diet. A chicken when hatched has bone and muscle, beak and claws, skin and feathers, eyes and internal organs. All these have been developed from the material stored within the shell as food for the life germ or embryo. The more one considers it the more wonderful this seems. The white of the egg is largely albumen and water, and the yolk con- tains much albumen. This albumen is one of the important substances in the class of foods known as proteins. It hardens 3 oo GENERAL SCIENCE when heated as in the familiar case of eggs hard boiled. In the process of digestion when acted upon by the gastric FIG. 96. Candling eggs. and pancreatic fluids it is changed to peptone which more readily dissolves and osmoses. Chemically albumen is very closely related to a substance gluten found "~ in THE FARM 301 grains and to casein found in milk. (See pages 222, and 328.) When a food solid is treated with strong nitric acid, any protein is colored yellow. If it is then washed free of the acid and dipped into strong ammonia water, the color may change to orange. A piece of white silk ribbon shows these same tests for protein, while a white cotton fabric is un- affected. The cotton is cellulose, a vegetable fibre, and con- tains no protein. The preservation of eggs from times of over abundance and low prices to other times when the supply is much less, has been solved for the large centres of population by keeping great quantities of eggs in cold-storage warehouses. From these storehouses they can be supplied for sale as the market requires. Their food value is unchanged if they have been properly cared for, though they may be somewhat less palat- able than when fresh. Eggs for storage should be chosen with care, and any not strictly fresh must be rejected. There is much more food in a dozen large eggs than in the same number of small ones, and size may very properly be con- sidered in the sale price of eggs. The quality of an egg as to age and fitness for food can easily be determined by holding the egg between the eye and a strong light, preferably an electric light shining out through a hole in a box within which the light is placed. This testing should be carried on in a darkened room, too, so that one's sight is unaffected by any light other than what comes through the egg. With a little practice eggs may be graded almost as fast as they can be handled since with a little experience the condition of the egg is known at a glance. For family use on the farm the home product is often stored in large jars filled with a solution of " water glass", or sodium silicate, by means of which the pores of the shell are closed to air and to the germs that cause decay. In 302 GENERAL SCIENCE this case as in cold storage the eggs should be turned from time to time that the yolk may not settle to one side and become attached to the shell. Brooding hens turn the eggs upon which they are sitting, and when eggs are hatched in an incubator they must be turned one or more times. SUMMARY The hen as type of all domestic fowls illustrates the modifications accomplished in animal structures by long-continued selective breeding. Certain characteristics in build, coloring, and egg production have been intensified by retaining in the flocks year after year only those fowls which exhibit the desired characteristics in most marked degree. If domesticated fowls were turned loose and allowed to run wild in an uninhabited region, few if any of them would be likely to survive the conditions for which they long before had become unfitted. It is likely, however, that if any should survive their successive generations would rapidly revert to the smaller more active forms seen in the differ- ent kinds of game birds. A study of the skeleton of a hen in comparison with the skeleton of a human being shows that the hen walks on her toes. The lower, scaly, and often featherless part of the leg corresponds to the human foot. Where fowls are kept too closely penned up, and without sufficient freedom of range, they are less hardy, more likely to sicken and die, and are often infested with vermin. Shelter from cold and wet is essential to their healthy state. Most of the contents within an egg is material for the nourishment and growth of the embryo. The chick in due time, when the necessary conditions for hatching have been favorable, acquires the strength to break the shell enclosing it and to make its way out. The growth of the young chick from the embryo stage is by cell division just as growth occurs in the human body and in plants. A wonderful thing about it, however, is the variety of the organs (masses of cells doing the same kind of work in the body) that are made out of the material stored in an egg. Eggs may have in them all this stored material and yet be worthless for the hatching of chickens because destitute of the embryo. Its development when the egg is forming involves fertilization, which cor- responds to the fertilization of the ovules of flowers (page 265). Seeds THE FARM 303 that lack the embryo, regardless of the supply of food stored in them to nourish the growth of a young plant, never can germinate. The storage of eggs for considerable periods of time in condition fit for food takes into account the fact that their shells are more or less porous, and are an insufficient protection from the germs which cause decay. By sealing the pores in the shells with water glass, or by storing eggs at a temperature too low for the germs to multiply, the fitness of eggs for food may be maintained for long periods of time. They may be kept from times when eggs are abundant and low in price till when more scarce and of higher market value. Much of the value in the sales of eggs and poultry in the United States, amounting as these sales do to millions of dollars annually, represents thrift. Non-productive labor, and food materials for fowls which otherwise might be wasted, are thus turned into profit for the individual and wealth for the nation. Where poultry raising is carried on as a business, rather than an occupation incidental to general farming or as a pleasing home employ- ment, careful attention to all details of it is necessary, and considerable business ability is required in order to make it a success. In agricultural colleges courses in poultry raising are given for college credit. Much helpful literature is available free or at little cost, however, so that ordinary intelligence, coupled with painstaking care and an exercise of good judgment, will win success in the school of experience. Exercises 1. Is there any relation between the food value of eggs and the color of their shells? 2. What are the best ways of preserving eggs on a commercial scale? State what strength of solution of "water glass" is used to preserve eggs. Which are the best months for the storage of eggs? What purposes are accomplished in the storage of eggs? 3. Reproduce a diagram showing the cross-section of an egg, and on the diagram locate (a) the shell; (6) the outer and inner membranes; (c) the thicker and thinner parts of the white; (d) the chalaza; (e) the lighter and darker parts of the yolk; (/) the germ (embryo). 4. What food constituents of large value in eggs? For what foodstuff are eggs a substitute? What foods are best served with eggs at table? What are the digestive solvents for the albumen of eggs? What per cent of water is there in eggs? 304 GENERAL SCIENCE 5. Name several cooked foods that have eggs in their make-up. Of what use are eggs in making coffee? Why is it that the fresh shells may serve a like purpose? 6. What eggs other than those of hens are used for food? To what uses are spoiled eggs put? How is this possible? 7. Describe how eggs are "candled". What is the purpose of the air space found in the large end of the egg? What is the relative size of this air space in fresh and in stale eggs? 8. To what countries are eggs exported from the United States? Account for their export to Canada which is an agricultural rather than a manu- facturing or commercial country. 9. Name the various tissues of the body of the chick when hatched. Out of what substance within the egg have these been developed? Ascertain the literal meaning of the word protein. 10. In some general and striking way express the annual value of both the poultry and egg production of the United States (or of your own State). 11. How does the extent of the poultry industry exhibit national as well as individual prosperity? 12. Why is raising ducks and geese so much less common than raising hens? Why are so few turkeys raised? 13. What advanced high school science includes a study of the structure of domestic fowls? Why should studies of poultry be included in a high school course in agriculture? 14. What is true of the physical endurance necessary in raising poultry as compared with the demands of general farm work? 15. Name several of the breeds of fowls commonly kept for profit by poultry raisers. Mention some of the well-defined characteristics of each kind. THE HORSE Any discussion of the farm would be incomplete without a study of the horse. As one of man's most faithful and serviceable domesticated animals, the horse has long con- tributed in large measure toward the production and distri- bution of the world's food supplies. It is but a few years since the horse was relieved from the tasks of transportation on street-car lines, and as the sole source of power in moving boats over inland waterways. The stage coach was long ago replaced by the railway, and now even in warfare the motor truck lessens the need for horses. The part played by the horse in the world's history, as used by man in the THE FARM 305 ways of peace and for purposes of conquest, would make a most interesting narrative. The horse belongs to the vertebrates, or animals with spinal columns, and is in the division known as mammals. To this group belong such domestic animals as cattle, sheep, pigs, dogs, and cats, together with various wild beasts such as bears, wolves, lions, tigers, and elephants. The whale, too, is a mammal and suckles its young, and man himself belongs to the mammals. On the other hand, fish and birds hatch from eggs. From studies of the remains of animals found buried in the earth's strata geologists are able to give a detailed story of the ancestry of the horse. This history runs back through geological periods to animals entirely different in appearance from the horse of historic times. This evolution of the horse as it is called is an illustration of the changes that have occurred in plant and animal forms during countless ages. Those forms best adapted to changing conditions have sur- vived. They have perpetuated the characteristics and organs which have best served their needs and have been in most frequent use. Man himself has develope'd and per- fected various breeds of horses, cattle, poultry, and other animals, and a no less wonderful change has been wrought in the kinds and qualities of plant life by selective breeding. The achievements of the last half century in improving plants and animals for man's use and enjoyment has been scarcely less than marvelous. Horticulture, animal husbandry, and general agriculture especially have profited largely by well- directed persistent applications of scientific knowledge in these respects. The teeth of the horse in front are powerful incisors in both upper and lower jaws, enabling it to bite off grass rather than pull it off as the cow must do because of lack of the upper incisors. The back teeth of both horse and cow have 3 o6 GENERAL SCIENCE grinding surfaces suited for the use of- coarse dry fodder. Both horse and cow belong to the "order" of animals known as the herbivora, as contrasted with the flesh-eating carnivora such as the dog, cat, and tiger. The teeth of mammals vary widely in number, form, and arrangement. The canine teeth of the carnivora are fitted for grasping and tearing their prey. Instead of being set closely together as in human FIG. 97. Teeth of a horse. beings the teeth of mammals generally are more or less scattered along the jaws. In the horse the absence of teeth between the molars in the back of the jaw and the incisors in front leaves a place well suited for the bits of the harness. SUMMARY Unlike birds and the domestic fowls which hatch from eggs laid by the parent bird, horses belong to the group known as mammals which bring forth their young alive, and nourish them on milk from the body of the parent. In the jaws of mammals generally the teeth are more or less scattered. Advantage of this is taken when the horse is harnessed for driving. The bits are put into its mouth in a place where teeth are lacking. THE FARM 307 The teeth of flesh-eating animals are characteristically sharp pointed, fitted for grasping and tearing their prey. But the horse belongs to the herbivora with broad flat molars suited for grinding coarse vege- table fodder, and with chisel-shaped incisors for biting off grass in feeding. The horse ranks as one of the most intelligent of the lower animals, and is capable of being highly trained. As one of man's most useful servants, and as a companion obedient to all demands made upon him, the horse has played a prominent part in the affairs of mankind. Exercises 1. What has early training, or lack of it, to do with the behavior of horses? 2. What constitutes "good habits" whether in persons or in horses? 3. Name several uses of horses for which automobiles are not well suited. 4. What considerations of public health make fewer horses in town and city a desirable thing? COWS, AND THE DAIRY INDUSTRY The cost of meat as a regular part of the food supply of an individual and a family is a matter of serious consideration. The industrial development of the country and the conse- quent increase in its population of consumers, together with the conversion of lands once cheap and devoted to cattle raising into high-priced farms devoted to other agricultural pursuits, operates even in times of peace to raise meat prices to a point almost prohibitive to those of small incomes. So complete is government supervision of the meat prod- ucts of the great packing houses that there is little need of any fear of the wholesomeness of meat sold in the markets. It is in the prepared forms of meat, such as sausage, that there may be use of preservatives and of adulterants (cheaper material as a "filler"). No meat should ever be used without having been thor- oughly cooked. From insufficiently cooked lean pork trichina may be introduced into the human body causing sickness and death. Tapeworms come from uncooked fish, 308 GENERAL SCIENCE beef, and pork. The high temperature of the cooking process kills these larvae, and at the same time destroys any other living germs. The milk supply is a much more serious problem so far as purity is concerned. It is one of the chief foodstuffs of people, especially for infants and small children, and it may easily become a menace to health. The dairyman is indeed a neighbor to us all in his care, or carelessness, as these affect FIG. 98. Pasteurizing milk. Heating and cooling done by circulation first of hot and then of cold water. our health. Since it is almost inevitable that town dwellers are dependent upon the milkman for their daily supply, city authorities acting as Boards of Health exercise close supervision over the conditions under which milk is sold in a city. The use of stoppered bottles for milk should always be insisted upon. But this is no sufficient guarantee that the bottles may not have been carelessly sterilized, or washed in water containing disease germs. The germs of typhoid, THE FARM 309 diphtheria, scarlet fever, and possibly of tuberculosis may be carried by milk that has not been pasteurized, i.e., heated from 150 to 160 F. and kept at that temperature for twenty minutes. Milk peddled in open cans and buckets FIG. 99. Dr. Stephen N. Babcock, inventor of the test for determining the per cent, of butter fat in milk. (Courtesy of Agricultural College, Univer- sity of Wisconsin.) is always to be avoided. The demand for a pure milk supply of necessity increases the cost of milk to the consumer. Modern dairy farming with its high-priced high-bred cows, its expensive dairy outfits and farm buildings, expensive 310 GENERAL SCIENCE farmlands, and high wages for labor, requires large capital and much business ability to make it a success. There must be no waste in by-products, no heavy outlays for feed that can be produced on the home farm, no waste in fertilizer for keeping this farm land at its highest productive stage, and no failure to make the products of the dairy yield the best financial returns. In other words successful dairying requires the intelligence and business ability in all its details that any successful business demands. Illustrative of the industrial changes wrought in the last generation in this country as a result of the widespread use of machinery, it is interesting to note that a large share of the butter product of the country is now made up in the cities rather than on the farms as was formerly the case. Suspended in the watery part of the milk are finely divided fat particles. They are held in this condition by the protein in milk known as casein. Liquids of this character are called emulsions. By the use of cream separators at the dairy farm the butter fat is taken from the milk and sold to representatives of some creamery, located it may be in a distant city, where the butter is made in great quantities by machinery instead of hand labor. The milk thus left on the farm is fed to pigs and calves. The drudgery of butter- making has been transferred from the women folks on the farm to an admirably equipped factory where every stage of the manufacture into butter is clean and sanitary. The cow in lying down kneels on the front legs first, with the hind quarters down last, reversing the order in getting up. In the case of the horse, the hind quarters go down first and are raised last. Scarcely any of the non-edible portions of the carcasses of cattle are wasted. The fat is not only used in cooking as suet, but for making oleomargarine. Portions unfit for these uses are valuable in candle-making and in the manu- THE FARM 311 facture of soap. The hides are converted into leather. From the hoofs, horns, bones, and the scrap parts, gelatine and glue are made. The bones are ground for chicken feed, and for fertilizer, or are charred to be used as boneblack in refining sugar to make it white. Both the hair and the blood have their uses. FIG. 100. Pasteurizing apparatus for use in a home. SUMMARY Meats of all kinds must be thoroughly cooked to destroy any trichinae there may be in .the lean meat from the hog, or tapeworms in the lean meat from cattle. Cooking is likely to render harmless any poisonous products present. So readily does milk serve as a carrier of germs of such diseases as typhoid and diphtheria that utmost precautions must be observed concerning the care of it from milking time to its delivery to the con- sumer. No one having an infectious disease should be permitted to have anything to do with handling milk. All dairy utensils must be thoroughly sterilized before use, and only water known to be uncon- taminated should ever be used in washing and rinsing them. Milk from which the butter-fat has been separated for sale to butter- making establishments is kept on the farm for use as food for calves, chickens, and pigs, and these animals become added sources of income in connection with the dairy industry. 312 GENERAL SCIENCE Exercises 1. Tell what difficulties are experienced in providing and distributing an ample supply of pure milk in large cities. Why is it that milk more than other foodstuffs may become responsible for much sickness? 2. What constitute sanitary conditions for a farm dairy? 3. What becomes of the cows found unprofitable for dairy use because of age or other reasons? 4. In what respects is dairy farming as a life occupation (a) rather attractive; (b) undesirable? In what respects is there less of drudgery about it than formerly? 5. To provide an ample food supply the year around for his cows, and to avoid excessive expenditures for ground feed, what crops may the dairy farmer raise? 6. Name several important considerations that largely determine whether or not a region is well adapted for dairying. 7. From livestock sold and shipped to distant packing houses for beef, what is the farmer as a consumer likely to buy back eventually in one form or another? Why are not all these various forms of foodstuffs and manu- factured products prepared in the home community? 8. How has it come about that both the tanning industry and the manufac- ture of shoes are carried on at a few centres only, involving as this does the expenses of transportation to and fro of the raw material and of the manu- factured product? 9. From what parts of the world are there importations of hides and beef? 10. What has caused the great increase in creamery-made butter, and the lessened amount of the "country-made"? Aside from the taste given to butter by salt, what purpose is there in its use? LESSONS ON CORN To travel all day by train through the corn fields of the Middle West at a time when the crop is in its stage of most luxuriant growth gives one an idea of bounty, prosperity, and promise that cannot be gained by any reading of crop statistics. The development of the agricultural resources of the corn-growing states of this country, and their growth in population and wealth within a half century, constitutes a wonderfully interesting chapter in the history of the United States. They have become in a very real sense the granary of the nation. THE FARM 313 Corn was once the sole crop of the season on the western farms as cotton has been on the southern plantations, and there was an accompanying impoverishment of the soil. Financial distress followed from crop failures and from low prices. As diversified farming has replaced this practice more and more, and suitable rotation of crops has taken the place of a one-crop system, improvement in agricultural conditions has been marked. FIG. 101. Corn production of the world. (Robbins.) In 1916 the world's production was 3,818,700,000 bushels. (U. S. Department of Agriculture.'} Need of conservation of the fertility of soils that were formerly regarded as inexhaustible in crop capacity has become too apparent to ignore. It has been found that by the use of alfalfa (or other plants of the same family of legumes), and by the rotation of crops, materials for plant food are restored to the soil. Through the agency of " nitrogen-fixing" bacteria, soil fertility can be maintained in a degree somewhat comparable with the improvement of soils in the dairy districts through the use of barnyard fertilizer. The corn-growing districts of the world are limited by 314 GENERAL SCIENCE reason of climatic conditions. To mature the crop requires about four months from the late frosts of spring to the early freezes of fall. So vigorous is the growth of the corn plant that abundance of water and of plant food must be available. The demand for moisture is especially heavy at the time when the ears are forming. The corn plant has a most ex- tensive root system of the fibrous form penetrating the soil to long distances in all directions. In the growing season the FIG. 1 02. Relation of corn crop (dotted line) to rainfall (solid line). quantity of water that passes from the leaves into the air by transpiration demands an excessively large supply daily from the soil. To conserve the moisture content of the soil requires that the surface layer be kept finely pulverized, and that the ground be kept free from weeds which rob it both of moisture and of food material. The corn plant has a relatively large amount of leaf surface, and a correspond- ingly large amount of chlorophyll by means of which the production of food for plant growth occurs. THE FARM 315 Corn is a good example of plants bearing two kinds of flowers. Those of the " tassel" at the top of the plant have stamens in whose anthers an abundance of pollen is produced. Lacking the part of the flower known as the pistil they are staminate flowers. The "silk" of the corn consists of unusu- ally long styles of pistillate flowers at whose outer ends are the stigmas. At the inner end of each style is an ovule, which develops * in to a! grain (kernel) of corn. The corn ear is a mass of seeds securely enveloped by leaves (husks) closely crowded together upon a much shortened stem. The development of the ear and the consequent production of a crop of corn depends upon the fertilization of the ovules by the pollen cells that fall upon the stigmas. Any complete discussion of the fertilization of flowers, and of the fascinat- ing teachings of plant growth and reproduction, requires a study of Botany. There are many examples of pistillate flowers on one plant and staminate flowers on another. This is true of the cottonwood, poplar, willow, and box-elder trees. When a union of the parts from the pollen and the ovule has occurred, there results a new cell capable of development under favorable conditions into a new plant of the same species. The seed consists of this new plant as an embryo, together with a store of food for it when germination occurs and a protective covering for both. The corn depends upon the wind to scatter its pollen so that every ovule may be fertilized, and the ear of corn have no missing kernels. That this is commonly accomplished is illustration of the lavish provision of nature in the supply of pollen. A large amount of it must inevitably be wasted. Unfavorable weather conditions at the time when the pollen is being shed, either very dry and hot, or a long continued rainy period, may seriously cut short the crop of corn. 3i6 GENERAL SCIENCE Whether corn-raising is profitable or not depends upon the cost of production relative to the market value of the crop produced. To increase the number of bushels grown per acre on the farms of the nation without any corresponding increase in cost of production adds to individual and national wealth. The agricultural colleges of the country are en- gaged in experimental work to this end. They also give courses of instruction concerning the character of soils and their improvement, the nature of tillage for particular crops, the selection and advantageous use of seed in crop growing, the cultivation of growing crops, and the manner of harvest and storage and disposal of these orops. To these courses in Soils, Crops, and Farm Management, are added others in Dairying, Animal Husbandry, and Horticulture, thus illus- trating the diversity of interests involved in general agricul- ture. As preparation for these courses there is need of some knowledge of high school Botany, Chemistry, Geography, and Physics. The list of uses of corn is a long one. The dry stalks with their leaves are excellent fodder for cattle. Cut into short lengths when green, the whole stalk with its leaves is exten- sively used for filling silos to furnish feed for cattle, especially on dairy farms. Less hay is needed where silage is provided, and the quantity of milk from dairy cows is increased. The corn itself (as ground feed preferably) may be worth more to the farmer when converted into beef and pork than when marketed as corn. Bread, cakes, puddings, and hominy are appetizing corn foods. Corn meal by reason of lack in gluten requires wheat or rye flour mixed with it in making corn bread. Corn starch both for table and laundry uses, corn syrup, grape sugar, and corn oil are all extensively manufactured. Sweet corn from the garden and in cans adds variety to the vege- table food supply. THE FARM 317 SUMMARY Corn can be raised only in those regions where the growing season is four months or more free from frost. Its vigorous growth is most noticeable during the long summer days of hot sunshine, and when it is warm throughout the nights. The demands of corn upon the soil for moisture are very heavy, especially at the time when the ears are forming. So wide and deep does it root that where the soil was thoroughly prepared in the spring, and when the surface is kept loose and free of weeds, a corn crop will stand a long period of dry weather without serious harm. The long streamers of leaves are admirably adapted for exposure to sunlight, and for absorption of large amounts of carbon dioxide from the air, and for ridding the plant by transpiration of the large quantities of water required in its growth. The so-called veins running parallel and lengthwise of the leaves are a continuation of woody fibres found in the stalk. The corn plant bears two kinds of flowers. The ovules after being fertilized become kernels of corn, and they are arranged along a short- ened stalk or cob. The pollen is so abundant that under all ordinary conditions every ovule is fertilized, and there are no kernels lacking on an ear. The value of the corn crop exceeds that of any other product of the United States. So important is the selection of seed corn, its proper care till planted, and the testing of it for its power to germinate, that special instruction is given in all these details in agricultural colleges. By careful atten- tion to improving the kind of corn best suited to any region, larger returns per acre may be had with the same outlay. This is a matter of profit to the owner of the crop, and an increase in the wealth of the nation. Starch for cooking purposes, and for laundry uses, is made in enor- mous quantities from corn. So are glucose as a syrup for table use, for cooking, and for confectionery, and grape sugar with all its varied uses. One variety of corn when well popped gives delicious and wholesome eating. Sweet corn in season has much use as a vegetable fresh from the garden, and as green (unripened) corn it is canned in enormous quantities. Exercises 1. What is the meaning of the term "corn" in the Bible? 2. What is the first that is known of maize, or Indian corn? Give the GENERAL SCIENCE THE FARM 319 Indian legend of the origin of maize as told in Hiawatha. Tell something of corn in connection with the history of the early settlements in this country. 3. Name seven of the greatest corn-raising states of the United States. What portion of the world's supply of corn (maize) does the United States produce? Where are the corn-raising districts of the world? Why do such limitations upon its production exist? 4. At what season of growth is considerable rainfall indispensable to the corn crop? What is true of the amount of sunshine (clear days) required by corn as a crop? 6. What kind of soil, and what kind of land surface, favor the raising of corn on an extensive scale? 6. Which portion of the kernel is relatively rich in starch? 7. What is (a) hasty pudding; (b) hominy; (c) corn syrup; (d) grape sugar? 8. Name several of the forms in which corn is put on the market as a food. Discuss the manner of preparation of some one of the "breakfast foods" made from corn. 9. What is denatured alcohol? Why is it denatured? What are some of its uses? 10. Describe a scheme for testing seed corn as taken from the ear. Why not use corn which has been long shelled for seed? What per cent should germinate before it is considered good enough to plant? Why test corn at all? 11. What is kaffir corn? How is it unlike maize? APPLE RAISING AS AN INDUSTRY When at a fruit stand one purchases an apple to eat or orders home from the grocery a bushel of apples for family use, there is occasion to wonder why this product of farm and orchard in a large part of the United States should be so expensive as compared with the cost of tropical and semi- tropical fruits shipped in from more distant regions. In the earlier history of this country apples were available in most homes for generous use, oftentimes the year around. There was apple sauce and baked apples for the table, together with apple pies and apple puddings. From bins and barrels in cellar and cave there were apples to eat at all times in accordance with one's choice in flavor and in quality. The apple in some one or more of its many uses as food formed an important item of diet. GENERAL SCIENCE . FIG. 104. Apples from a tree unsprayed. Only those in the basket are mar- ketable. FIG. 105. Apples from a tree sprayed. Those not marketable are in the basket. THE FARM 321 By reason of the codling moth, whose larva (lar'-ve) are the " worms" found in apples, the production of market- able apples without the labor and expense of spraying FIG. 106. Work of the codling moth. the trees several times in a season is almost impossible. This insect pest is an importation from the apple-growing districts of Europe, and its advent has caused the loss of millions of dollars annually in the apple crop of the country. 322 GENERAL SCIENCE Many of the old time orchards have been allowed to go to destruction, given over to the ravages of worms .and to such diseases as the fungus growth called " apple scab." For- merly every home had its apple trees about the house, and every farm its orchard. Now apple raising is a highly spe- cialized industry employing a large investment of capital and expensive outfits in machinery and appliances. It demands much business ability successfully to finance, raise, and mar- ket the crop. m The agricultural colleges of the country have done much in their courses in horticulture to make possible the success that to-day attends the effort to supply again to the American people an abundance of apples as a most wholesome and appetizing fruit. To fight successfully the insect pests that attack the crops of the farmer, and the various parasitic growths like the apple scab, the rust on wheat and oats, and a long list of bacterial diseases, there has been rapidly developed the need of a scientific education in agriculture as an occupation. Biological and physical sciences as applied in agriculture are an indispensable preparation for success- ful farming. Instruction once gained only through expe- rience on the home farm is now given as courses in college. The material used as a spray for the codling moth com- monly contains some compound of arsenic. Paris green is often used. The purpose is to coat both the leaves, and the fruit (preferably just after it has been formed, and shortly after the blossoms have fallen) with a fine spray of the poison- ous material. The larvae hatched from eggs laid by the moth in the early spring are killed by feeding upon the foliage and fruit. Lime when slaked is a fine white powder, and when mixed with the water containing the Paris green and applied to the foliage in the spray, shows by its whitening effect just how evenly and completely the application has THE FARM 323 been carried out. Any material for the purpose of destroy- ing insect life on plants is known as an insecticide. " Bordeaux mixture," containing copper sulphate along with some lime in the water, is used as a spray for the purpose of destroying fungus growths. It is a fungicide. To apply these sprays in the form of a fine mist that shall completely cover the foliage, twigs, and young fruit, requires FIG. 107. Spraying the trees. An outfit suitable for a small orchard' a force pump operated at a pressure of one hundred pounds or more. The expense of equipment, and the amount of labor required to keep apple trees healthy and their fruit fit for use when grown, is a serious handicap in fruit growing on a small scale. To the botanist the group of plants known as the fungi is of the greatest interest. They have in them no chloro- phyll for the manufacture of food for themselves. They live and thrive upon what they appropriate from other plants or from animals. The yeast plant is a fungus, and 324 GENERAL SCIENCE so are the moulds that grow upon foodstuffs, and the rusts and mildews that are so destructive of grain crops. They are parasites (see page 40), and are the cause of losses in agriculture estimated at hundreds of millions of dollars annually. Bacteria form a class of plants closely related to the fungi. In man's struggle for existence the microscope has made possible a knowledge of these hidden agencies which have so long worked havoc with his food supply, with his health, and with life itself. In the field of agriculture science has scored some of its greatest triumphs. Intelligent as well as persistent efforts are necessary in order to be assured of success in a never ending warfare against insects and plant diseases. It must not be forgotten that in this warfare the birds are man's friends, and an active agency in the destruc- tion of insects. SUMMARY It is an easy matter to buy and set out apple trees, and to get them to grow till large enough to bear. But there is occasion to wonder why the apples growing upon them are so poor oftentimes, and the trees so" short lived. It is only by persistent efforts that the destruction wrought by the codling moth can be combated successfully. Various fungus growths sap the strength of the trees, and finally kill them. To spray successfully trees with large tops, using the poisonous com- pounds either as a liquid or as dust, requires a powerful force pump, or a compressed air outfit. To move the equipment and the materials used from tree to tree through an orchard, and to furnish the necessary labor for several applications every season, involves much expense. But it is only by spraying that the trees and their fruit can be saved. The fungi are a class of plants wholly destitute of chlorophyll, and therefore utterly unable to prepare food for themselves from the raw materials of sap water from the ground and carbon dioxide from the air. As parasites the fungi thrive by living upon the food prepared by other plants that do have chlorophyll, thus robbing those other plants and possibly in time starving them to death. The annual losses in the agricultural productions of this country -from fungus growths on THE FARM 325 various fruits and cereals are estimated at hundreds of millions of dollars. Oranges, lemons, and other like fruits, have rinds that protect them from the bacteria which cause decay. But the skin on apples is thin and easily broken. In spite of a wax-like covering that in some apples is quite noticeable, not only does water escape through the skin so that the apple shrivels, but bacteria penetrate it and cause rot. When apples have been carefully selected and handled, wrapping them separately in paper lessens the likelihood of their decay. WHEAT AND WHEAT GROWING So common has been the use of wheat flour in the United States that it is difficult to readjust the manner of living when compelled to do without it either wholly or in part. So widely distributed geographically are the wheat-growing regions of the earth, and such is the range of climatic con- ditions under which different varieties of wheat may be grown profitably, that a world-wide crop failure is unlikely. But it is quite possible under normal conditions that the world's demand for wheat may increase more -rapidly than any increase in its production, resulting in a rise in its price, and of the flour made from it, until the cost of wheat bread is prohibitive for many. Better methods of wheat culture may increase the average yield per acre materially through better tillage, and more careful selection of seed. It is possible that large areas of land now considered unfit for wheat growing, especially in the semi-arid regions, may be brought into use with newly propagated varieties of wheat suited to these unusual climatic conditions. It is possible that scientific farming may secure increased fertility of soils in spite of repeated croppings with wheat. Any gains of this nature are, how- ever, likely to be slow. They can only serve to delay the coming of the time when wheat bread with butter or with 326 GENERAL SCIENCE THE FARM 327 milk shall no longer serve as a simple and well-balanced food supply, inexpensive enough to come within the means of every one who is willing to work. With the development immediately following the Civil War of the trans-Mississippi region, and then later of the great Canadian Northwest, together with the use of the wheat lands of Australia and of Argentina in South America, the wheat supply of the world increased much faster annually than did the wheat-eating population of the world. But there are no longer any such extensive areas of fertile soils waiting the plow to convert them into wheat lands ready for the seeding. During all this period of relatively cheap wheat and flour it is estimated that one- third of the earth's population has subsisted chiefly upon rice as a cheaper grain. It is owing in part, also, to the large use of machinery to plow, to reap and bind, to thresh and market the grain econom- ically, so far as labor is concerned, that the prices have been maintained at so low a level. With farm lands increasing in value, and with a higher price for labor in the wheat- growing districts, there is an increased cost of production. The need of labor is very great at the harvest seasons. At other times a relatively few men with modern outfits of farm machinery can give the necessary care to the largest wheat farms. This condition does not operate to distribute the population of the country, nor to make easy the problem of bringing together the work that needs to be done in agricultural districts and the men who are seeking work. Where wheat raising can be carried on with corn growing, and with other and diversified farm interests, the require- ments for labor are better distributed throughout the year, and employment is given to more persons the year around. The large per cent of gluten in wheat gives it a food value 328 GENERAL SCIENCE far in excess of corn or rice. Gluten is a protein food of great worth for tissue building. It is the gluten, too, that gives to flour when mixed with water the peculiar consistency that makes possible its being " raised" into the familiar forms seen in loaves of bread and cake. When once raised, and then subjected to sufficient heat in the process of baking, the loaf retains its shape by reason of the hardening of the gluten. The wheat kernel is rich, too, in those mineral constituents which build up the bones of the human body. These compounds, to become available for bone building, must be dissolved. Other grains less extensively grown than wheat, such as oats and rye, are also rich in gluten and in mineral content. Rice is almost wholly a starch food, and as such lacks in tissue-building value. In the milling process it is possible largely to eliminate the gluten. The flour is somewhat whiter in appearance and makes whiter bread, but it has less of food value. The bone-building value is likely to be deficient in these white flours. From the big flour mills, such as those in Minne- apolis, flour is shipped to all parts of the world. The daily output of one mill may be thousands of sacks. The outer part of the kernel as separated from the pulp is sold as feed for farm animals under the name of bran. The mill product known as " shorts" contains much of the bran along with considerable of adhering starchy portions. Dairymen in the past have bought and fed to their cows large quantities of both bran and shorts. Under stress of war conditions much of these parts of the wheat^are retained in the flour and other wheat products for human consumption. The old- time grist-mill has largely disappeared from rural communities where it was found in the earlier days. In the great wheat districts the crop is loaded from elevators into cars, and railway transportation enters into the problem of feeding the millions who use wheat. THE FARM 329 SUMMARY The leaves of the wheat plant like those of corn are lance-shaped and parallel veined, and at their base form a sheath about the stem. The roots, too, are fibrous as in corn, but the stems are hollow rather than filled with pith. The general characteristics are such as to class the wheat plant among the grasses. The same is true of the cereals gen- erally. The hollow stem of the grains gives a maximum of strength for the amount of material necessarily provided by the plant in the growth of the straw. An increase in the wheat-growing areas of the world through develop- ment of varieties of wheat suited to regions where it cannot now be grown successfully; an increase in the yield per acre of the varieties now LEADING COUNTRIES /M ACREAGE rr/LLIONS OF ACRE'S /f JO 4S 60 BUSHELS PER ACRE Russian Empire United States /nd/a Argentina France ._ Austria Hungary Italy . Canada FIG. 109. Wheat production of various countries, and bushels per acre- In 1916 the world production was 3,823,667,000 bushels. (U. S. Department of Agriculture.') raised; and the maintenance unimpaired of the fertility of wheat- growing soils, are problems of the greatest importance in feeding the world's population now and in the future. While other cereals such as rice and corn are rich in starch, the large content of protein in the gluten of wheat makes all the wheat foods especially valuable as body builders. On the great wheat farms of the United States and in Canada so much of the labor of raising the crop is done by machinery that the de- mand for labor is small except at harvest. At that time the crop must be gathered within a few days' time to prevent loss. Not infrequently harvesting goes on during moonlit nights. The extra help needed dur- ing the harvest must at other times of the year find employment else- where. Diversified farming on the other hand provides employment for laborers the year around. 330 GENERAL SCIENCE Exercises 1. Name the chief wheat-growing states of this country. In what parts of the United States is wheat not largely grown? What apparent reasons for this difference in crop interests? Compare conditions for corn and wheat raising as to (a) climate; (6) character of soil. 2. Name in order of production the wheat-growing countries of the world. 3. Why is it that wheat is not grown more extensively? What possible substitutes are there for wheat in the feeding of people? 4. What are the earliest records of wheat raising? When was wheat introduced into this country? 6. Name several kinds of breakfast foods wholly or largely made of wheat. FIG. no. Percentage of the wheat crop of the world (1915) grown in differ- ent countries. (Robbins.) 6. What period of time under favorable circumstances is required for the germination of wheat? 7. Upon what does the market price of wheat largely depend aside from the cost of production? 8. At what times in the year does the wheat crop require most labor? What attention is given it at other times? How does the labor required com- pare with that bestowed upon a corn crop ? What labor conditions neces- sarily exist in wheat-growing sections? 9. What variety of wheat is most largely grown in your section of country? Name some other varieties. Give their respective merits, and any spe- cial conditions necessary to their growth. What is meant by "hybridi- zation" in plant growth? 10. Describe in detail (a) the preparation of land for wheat raising; (b) the methods of seeding; (c) any cultivation or other care of the crop till har- vest; (d) the harvesting of the wheat. THE FARM 331 11. What were the early methods of wheat harvesting? What has been the effect of harvesting machinery (a) on the labor required to raise wheat; (b) on the cost per bushel? 12. How much wheat is used per acre as seed? How deep is it put into the ground? When is wheat fit for harvesting? 13. Describe early methods of threshing? What advantages are there from threshing in the field immediately after harvest? In what sections only can this practice be followed? What are several purposes in stacking wheat or in housing it in barns before threshing? W 7 hat is the "chaff" when wheat is threshed? FIG. in. Cutting and binding wheat in the old way. 14. What is the range in yield of wheat per acre in the United States? At eighty cents per bushel, what value is represented in the 900 million bushels of the 1 9 1 4 wheat crop ? Allowing six bushels per person for home consumption in the United States, what was the excess for export? 15. Describe the various steps in making wheat flour. What is meant by the "bolting" of flour? 16. In milling wheat, about what per cent is separated as bran? How does bran differ from shorts? What is "whole wheat flour," and how does it differ from graham flour? What is "self-raising" flour? 332 GENERAL SCIENCE 17. Of what nature is the "rust" on wheat? What harm results from it? What is meant by parasitic plants? What course may be pursued to save wheat from rust? What treatment of seed wheat may be employed to lessen "smut?" ORIGIN AND NATURE or SOILS To the careless and indifferent mind the term soil may have little significance. As dust it gets into our eyes, and it makes the life of the house-keeper a burden. As mud it clings to one's shoes, and it makes travel and transportation by high- ways both irksome and expensive. To the botanist, how- ever, soil is the source whence the higher types of plants get their food material in large part, and in which the mightiest oak and the tiniest violet alike find root. To the zoologist it is the abode of innumerable forms of animal life. To the farmer engaged in raising crops the depth, the texture, and the chemical nature of the soil tilled by him is of utmost importance. He must have knowledge of the kind of crops likely to be most productive. He must learn ways of con- serving the fertility of the soil, and of managing it most profitably. Courses in agricultural colleges involving a study of the origin of soils, their waste and restoration, their characteristics and management, and the effect upon soil structure of plant and animal life, require a knowledge of Chemistry, Geology, Physical Geography, and Physics. In an attempt to classify and name soils, no mere descrip- tion can take the place of actually handling some well-chosen types, and of learning through first-hand acquaintance to recognize and name all local varieties of soil. Very largely soils may be described by making combinations of the terms gravel, sand, clay, and loam, along with descriptive adjectives advisedly chosen, e.g., a light sandy loam, a stiff clay soil. Silt is composed almost exclusively of very fine particles of earthly material such as the sediment from running waters when their current is checked. When dry it crumbles read- THE FARM 333 ily. Clay consists largely of yet finer particles that rub between the fingers when dry much as does flour, and when wet form a soft plastic mass which hardens into lumps on becoming dry. A loam is characterized by no particular size of particles, but is loose and friable even when quite wet. Running water as an agent in erosion has been discussed in a preceding lesson. It is to be noted here, however, that in the transportation of eroded soils there is accomplished a sorting of material according to fineness which results in beds of sand in some places, a mud deposit as silt in another, and clay banks elsewhere. From an agricultural point of view this sorting is an unfortunate one when these lands come under cultivation. It is one of the problems of scientific farming to know how best to modify any particular soil by the addition at least possible outlay in time, labor, and capital of those materials which improve its fertility, struc- ture, and conditions for tillage. Any sample of soil gathered from field, garden, or roadside commonly has in it vegetable matter in different stages of decay. This may be burned out by keeping a weighed sample of the soil at a red heat for some time in an open iron or porcelain dish. Any loss of weight due to this treatment of a thoroughly dry soil represents the amount of organic matter of both animal and vegetable nature that was in it. The very large per cent of the soil sample remaining is the mineral portion. Rock material in a finely divided state constitutes very largely the "soil" in which plants root themselves. From it they obtain the water and all other food material necessary to their life and growth except carbon dioxide. Soils have been formed by disintegration of the rocky crust of the earth, a process that has been going on for all the ages. When their fertility (crop productiveness) has once been wasted it is restored naturally only after long periods. The 334 GENERAL SCIENCE nature of these soils, aside from the organic matter in them and the material in the rock originally, also depends upon the chemical changes that may have accompanied or fol- lowed the disintegration of the rocks. Water is perhaps the chief agent by means of which the rocks have been broken down and reduced to a finely divided * FIG. 112. Stratified rock, the origin of which dates back to a time when the material in it was deposited as a sediment in layers originally horizontal. condition. By its freezing and thawing, by its solvent action and its powers of erosion when in motion, even the hardest of rocks are slowly worn away. Rocks exposed to the direct rays of the sun on mountain sides are subject to rapid expansion and contraction of their surface layers due to daily temperature changes. As they crumble the fragments are blown away, or are washed down the slopes. Carbon dioxide gas in solution, and waters THE FARM 335 strongly alkaline, have rapid solvent action upon certain rock materials, accompanied by chemical changes that con- tribute to their reduction. Decaying vegetation in the soil yields acids, and these acting on the rock material aid in bringing about its disintegration. The rock known as granite contains among other con- stituents the minerals feldspar and quartz each of which has a definite chemical composition. The feldspar when it is exposed to the action of the atmosphere slowly disintegrates, giving rise to clay. The quartz particles as sand grains may remain mixed with the clay to form loam, or may be separated from it by running water and both deposited in beds sepa- rately as sand and clay. Vast areas of soil often of great depths have been transported by the action of streams and laid down where we find them. In these soils sometimes clay predominates, and sometimes sand. SUMMARY Rocks are a mixture of various chemical compounds such as quartz, feldspar, hornblende, gypsum, and "limestone". The rock constituents of definite chemical composition are called minerals. It may be supposed that originally the earth's land surface was composed of rock only. By reason of expansion and contraction due to temperature changes, by the expansion ol water in the rock crevices when it froze, by the chemical action of carbon dioxide in the air com- bined with water as carbonic acid (H 2 CO 3 ), and by various other agencies, this rock crust became broken and pulverized giving rise to soils. So long as it remained in place this soil covering protected the rock below from further weathering. Running water, however, trans- ported this broken rock material elsewhere, and deposited it in enor- mous quantity and to varying depths as sand, clay, and loam. Mixed with the earthy material of the soil is more or less of vegetable material in all stages of decay. And in and through it, especially the surface layers, are varied forms of animal and plant life so that instead of being dead inert material the soil commonly may be considered as teeming with life. XIV. PHENOMENA OF LIGHT SHADOWS AND ECLIPSES The illumination in front of the headlight of a locomotive or of an automobile, or one caused by some powerful search- light, is a familiar sight. The effect is the more startling when the air is filled with minute water particles at times of a fog, or when there is much fine dust or smoke in the air. If into the space thus strongly lit up a large opaque body enters, there will be a region of shadow extending outward from the body and away from the source of illumination. This shadow is the space from which the light is cut off by reason of the opaque body. A cross-section of this shadow region gives a form or outline like that of the body. If a screen is placed outward beyond the opaque body to receive the shadow form (cross-section), and it is moved further and further outward, it will be found that when the opaque body is larger than the light-giving body the shadow reaches outward indefinitely far. The area of its cross-section increases all the time. If the opaque body is smaller than the light-giving body, the cross-section grows smaller and smaller, and the umbra of the shadow has a definite end. The astronomer thinks of a body belonging to the solar system, and receiving its light from the sun, as at all times having on the side opposite the sun a shadow region pro- jected outward into space. The shadow of any planet always accompanies it in its course around the sun, as does the shadow of any satellite in its course around a planet. To the astronomer an eclipse of the moon is simply the passage of the moon into the shadow of the earth. In 336 THE PHENOMENA OF LIGHT 337 the somewhat indefinite but distinctly circular outline of this shadow he sees confirmation of his belief that the form of the earth is spherical. A so-called " solar" eclipse is to him the result of the moon coming between the observer and the sun. The shadow of the moon overspreads him as an observer, and it is really a case of an eclipse of the observer. It would be so called by observers elsewhere than on the earth itself. In those somewhat infrequent occur- rences where the moon comes directly in line between sun and earth, the astronomer is given a very few minutes of time when the sun's disc may be completely covered by the moon. He then has an opportunity to observe through the telescope the phenomena of the sun's atmosphere as it extends far out into regions not hidden by the moon. By aid of the telescope it is possible to get photographs of these appear- ances. The description of what is seen at these times of a total eclipse of the sun, and the interpretation of this as given in texts on astronomy, makes fascinating reading. Some knowledge of the beliefs of astronomers concerning the universe, and of the basis for such beliefs, should be included in the schooling of all persons. It was from a study of the times of disappearance of one of the moons of Jupiter which suffers eclipse every few days, and from his interpretation of what these signified, that Roemer calculated the velocity of light as about 186,000 miles per second. So exact are the calculations of astronomers, and so regular are the movements of the heav- enly bodies, that it is possible to state (from calculations) the time of occurrence of any eclipse in the past or in the future, its duration, and where visible. The astronomer deals with distances and periods of time too great to be comprehended readily. But so exact are his measurements, and the calculations based upon them, that any slight depar- ture of his observations from calculated results leads to 338 GENERAL SCIENCE search for some unknown cause of the variation. Neptune, one of the eight planets of the family of the sun to which our earth belongs, was located (discovered) by astronomical calculations. The telescope verified its existence when the instrument was directed toward that part of the heavens where the hitherto unknown planet had been mathemati- cally located. SUMMARY A shadow is the space from which light is more or less completely shut off by an opaque body. It extends outward from the body on the side opposite the illumination. The forms seen on screens and walls, and commonly called shadows, are cross-sections of the shadow region. An eclipse is a phenomenon where an illuminated body darkens or completely disappears by reason of its entering the shadow of another body. An eclipse of the moon occurs when by reason of its revolution it comes into the shadow of the earth. Astronomers can calculate the times of occurrence of eclipses with the greatest accuracy. The outer portion of the sun is an atmosphere of gases and vapors thousands of miles deep, and this atmosphere is so highly heated as to be luminous. From this "solar atmosphere" light and heat come to the earth. In it are found in gaseous form nearly all known chemical elements. The existence of non-luminous bodies far out in space, and wholly invisible because they are non-luminous, is made known to astronomers by the effect they have upon the motions of bodies which can be seen. Where the actual position or path of motion of a luminous body differs materially from its calculated place, astronomers feel justified in asserting the existence of one or more invisible bodies whose pull of gravitation occasions the change in position or in motion. IMAGES BY REFLECTION IN PLANE MIRRORS For a satisfactory understanding of the common phenom- ena of image formation in plane mirrors such as looking- glasses, a knowledge of the theory of light as taught in Physics is required. Whatever light may be (page 344), it is very THF PHENOMENA OF LIGHT 339 evident that the mirror has served to change its course, and to reflect it (throw it back) into the eye where the optic nerve is affected and sight a's a sensation results. Studies in Physiology and Psychology as well as Physics have to do with what occurs after light enters the eye, but it is the study of light before it enters the eye that concerns us here. It is evident that the location of the image in a plane mirror is determined by the light direction after reflection. The image as an apparent reproduction of the object is found to be located back along the lines of light that have come from the mirror into the eye. No matter to how many different eyes (people) this re- ^ fleeted light from the mirror f ! \ comes, it appears to originate in ! ! an image of the real object that has the same position behind the mirror for all observers. To FIG. 113. An image of any draw Straight lines from the eyes of point as seen in a plane mirror all observers back through the mirror to any Single point in that are equidistant from the mirror ^i_ J.-L v T-.L -L i surface, and corresponding image means that the light which points in both are in the same the Corresponding perpendicular (normal) to that & surface. originated at point of the object, must have been incident upon all parts of the mirror surface. In this way only could it be reflected to all observers so that the image of the point is at one and the same place for all. The complexity of this conception is much simplified by conceiving that from every point in either a luminous body, or of one illuminated (shining by reflected light), there is sent off a continuous series of every expanding light waves whose form is that of hollow concentric spherical shells. Now to represent the directions in which such waves are sent out, 340 GENERAL SCIENCE lines can be drawn outward in all directions from the point of origin as a center. There will be as many of them as there are radii (ra'-di-i) from the center of any sphere an innumerable number. Wherever any one of these lines comes to the surface of the mirror, at that point there is a change of direction. The incident line of light then becomes a line of reflected light. These reflected rays, then, are as many as there are points in the reflecting surface. An explanation of this location of images in plane mirrors may be given by diagrams. Let any two radial lines repre- senting rays of light be drawn from the same point of an object (such as one of its extremities) to points on a line representing a mirror surface 1 . These rays or directions after the reflection will still be diverging lines. If they both enter the eyes of any one observer, the apparent source whence they both seem to come will be back along both lines of reflection, and at the point of the apparent intersection of these lines. All observers getting reflected light from this same point of origin will locate in like manner all images of it at the same image point. An image of the opposite ex- tremity of the same object as a source of light is fixed in the same way. So are all intermediate points. Any observer getting at least two rays of light from every point on the side of the body toward the mirror will locate in the same way the image of every one of these points. These im- age points will have the same order of arrangement with re- ference to one another as was true for the points whence the light originated. For diagrams in the class room the im- ages of the two extremities of an object only are located, and the parts between are filled in without construction work. With polished surfaces it is believed that the effect of the mirror is simply to change the direction of 'the lines or rays of light at the mirror surface, their directions relative to one 1 Preferable these points should be close together. THE PHENOMENA OF LIGHT 341 another remaining the same. But when light falls upon unpolished surfaces, the reflection is of such a character that the reflected rays no longer maintain the same relative direc- tions to one another. They are so scattered in their relative directions as to make image formation as discussed above impossible. Reflection of this sort is called diffusion. It is to diffused light that we owe the freedom from images in all smooth surfaces by which we are surrounded, and the even- ness in distribution of light within our rooms and out of doors. FIG. 1 14. Diffusion of light is scattered irregular reflection owing to rough- ness of the reflecting surface. (Tower, Smith & Turton.) SUMMARY In reflection of light the ether waves are thrown back from the re- flecting surface into the same medium whence they came. But a change in their direction due to their passage obliquely from one medium into another of different density is known as refraction. An image is an apparent reproduction of an object. This appearance is due to the fact that the light which originally comes from the object itself enters the eye in a direction such that it seems to originate in the image position. The image of any point of an object is at the place of intersection of two or more lines of light from that point after they have been re- flected or refracted. This intersection is often apparent rather than real as in case of images in plane mirrors. All these image points have the same relative position to one another as do the corresponding points in the object, thus reproducing the object so far as form and general appearance goes. Where light is reflected from surfaces not sufficiently smooth, the relative directions of the light rays is not the same after reflection as 342 GENERAL SCIENCE before. This phenomenon is known as diffusion, or diffused reflection. No images are formed as result of it. Some of these image positions are such that a screen placed there will show the image upon it. One could lay hold of the image by grasping it in the hand if it were only something tangible. Such images are said to be real. Virtual images are those where this is impossible, their positions being apparent and not real. The light does not even get where the virtual image seems to be. In plane mirrors the virtual image of an object is so located that every point in the image is as far back of the reflecting surface as the corresponding point of the object is in front of it, and a line connecting these two points forms a right angle with the mirror surface. COLOR PHENOMENA In order to enjoy the natural colorings of sky and cloud and landscape, and the marvelous combinations and blend- ings of color in flowers and in the plumage of birds, it is neither necessary to make a study of Physics nor to under- stand the theories by which scientists explain color phe- nomena. One may become skilled as a painter of land- scapes, of historic scenes, or of portraits; he may be a master in the art of dyeing, and produce the brilliancy and variety seen in the various fabrics, and at the same time know nothing of the scientific explanation of these color effects. But the explanations of the nature of light and color as given in Physics simplify what otherwise would re- main an inexplicable and bewildering number of unrelated phenomena. The teachings of science concerning color phe- nomena is a good illustration of how advancement in learn- ing by individuals and by mankind in general becomes pos- sible through the efforts made by scientists to ascertain the nature and meaning of the various phenomena of life. When a beam of sunlight is passed through a glass prism, and into a room from which all other light has been excluded, it is possible by a proper adjustment of the prism to get on a screen or a white wall a band of overlapping colors like THE PHENOMENA OF LIGHT 343 those of the rainbow the so-called solar spectrum. The screen or wall serves simply to intercept and throw the " colors" back into the eyes of observers. These colors were in the sunlight that passed through the prism, and they were changed from their straight line direction as they passed into the glass and again still further as they emerged from it. This change in direction of the light is caused by change in density of medium. The color elements contained in sunlight are bent unequally, and they diverge more and more the farther the screen is away from the prism. This makes the spectrum longer and longer without completely sepa- rating the colors, or preventing their blending into one another. If now in the path of the emergent ray a blue glass plate is held, it is the blue light of the spectrum only (or largely) that gets through the plate. The other colors are almost wholly absorbed by the coloring material in the glass. If a piece of common window glass is used all the colors pass through it, while with red glass nearly all the colors but red are stopped by the glass. When both blue and red plates are put in the emergent beam together, none of the colors appear on the screen. Each of the plates has absorbed the colored light which the other let pass. By choice of the proper pigments to go into glass, and by varying their pro- portions, beautiful color effects indoors may be obtained with windows by combining in varied patterns glass of different colors. We say that glass is blue or red or any other color according to the kind (color) of the light it transmits. When only the blue light of the spectrum appears on the screen, and a sheet of paper (or any white object) is held in its path, the paper in a darkened room appears blue. But if a red screen be used instead of a white one, it looks black as result of absorption of the blue light. There is then lack 344 GENERAL SCIENCE of light to be reflected. If a red glass be used in the spectrum beam, any blue object upon which the red light falls will appear black, and a white body as a screen will look red in the red light which falling on the screen suffers reflection. Color in itself is just a light phenomenon due to the kind of light affecting the eye. Color as a property of bodies is determined by what color elements of any incident white light are reflected from it, and in what proportions. Thus it is that "selective absorption" accounts largely for the colors of objects round about us with all their wonderful variations. An object is said to be white when it reflects all the color elements of the white light incident upon it. Light reflected from bluing left in cotton cloth, combined with the yellowish light reflected by the natural coloring material in the cotton fibre, causes when received into the eye quite the same color sensation as does sunlight when reflected from a white wall. It is an illustration of what is meant by ' ' complementary colors . ' ' The theory that light is wave motion in an ether medium explains color phenomena. The mathematical accuracy of the theory is very striking. Briefly, the theory for color is that the nerves of sight seem to be attuned to respond to certain very definite numbers of vibrations per second coming to them as " ether waves". The eye is able to distinguish more or less sharply between at least seven different sets of these vibration rates the so-called spectrum colors. This is very much the same condition for the eye as that which enables the ear to distinguish vibration rates coming to it through the air or other material medium as the "tones" of music. The richness (quality) of any sound is increased by the blending of certain combinations of sound waves per second, making possible all the variations whereby we are enabled to distinguish the voices of our friends and acquaintances wherever heard. In like manner the blend- THE PHENOMENA OF LIGHT 345 ing of ether waves of different frequency (number per sec- ond) gives rise to all color effects, however wide their range in beauty and character. The waves per second said to give rise to the colors of the spectrum from red at one end of the scale to violet at the other extreme, are numbers so great as to be incomprehensible. This does not in any way make the theory less tenable, or its mathematical relationships less sure. It has been mathematically demonstrated that when once the wave theory is accepted all these color positions in a spectrum follow naturally. Spectrum analysis in Physics, in Chemistry, in Astronomy, and in the arts and industries, with its arrangement of color lines in order of refrangibility, makes possible a knowledge of the chemical composition of highly heated bodies at distances as great as that of the sun. Even the stars, at distances enormously greater, re- veal in their stellar spectra, something of their composition and of their motions. The fact that the solar spectrum not only contains the different colors distinguishable by the eye, but that they blend imperceptibly into one another in order of wave frequency, suggests that in the sunlight there are all lengths of ether waves 1 . The prism serves to sort out and group those of the same or approximately the same frequency. Not only does light from different sources vary in the num- ber of the color elements present, but it varies even more in the proportions in which these are blended. When physicists make studies of the solar spectrum in a room from which all other light is excluded, they find that in the region beyond the violet end there is evidence of the existence of ether waves of greater frequency (shorter wave- length) than the violet. These waves are of too great fre- 1 The lengths of the various ether waves causing color sensations is calcu- lated by dividing the velocity of light (about 186,000 miles per second) by the number of waves per second for any color. 346 GENERAL SCIENCE quency for the eye to recognize. Photographic plates put out in this ultra-violet region, and kept wholly screened from any light (ether waves capable of affecting the eye), suffer much the same changes as when exposed to sunlight. In fact the best part of sunlight for photographic purposes is that of the violet end of the spectrum. It is said to be rich in actinic rays. At the other end of the spectrum, and beyond the red of the spectrum sufficiently far to be in a region destitute of light, delicate thermal (heat) instruments detect the existence of long ether waves (waves of lesser frequency). These waves are incapable of affecting the eye to produce light sensations, but they are capable of heating effects. Not only are there ether waves recognized by us as heat and light, but there are electric waves propagated through space which are inti- mately related to the other wave motions. Perhaps the best illustration of this to-day is the transmission of electric sig- nals through the ether medium in wireless telegraphy. There is suggested in all this the possibility that all the so- called " forces," or forms of energy, transmitted through space without dependence upon any material medium, are closely related to one another and to the ether as a medium of transmission. It suggests, too, the possibility of forces wholly unknown to man as yet, and perhaps never to become known by reason of lack of any means by which to compre- hend them. SUMMARY Light is one of the forms of energy, and is capable of affecting the eye to cause sight or vision. Without eyesight knowledge of the exist- ence of light would be impossible. At the same time light exists whether or not there be any eye to receive and take note of it. The study of light in Physics has little to do with sight as a sensation. The accepted theory concerning the nature of light supposes the existence of a medium known as ether, and the transmission of the THE PHENOMENA OF LIGHT 347 light energy as a series of waves in this medium. The number of these waves per second (the wave frequency) may so vary as to give rise to all manner of wave lengths entering the eye from a luminous body. The eye, however, responds to only a relatively narrow range of these ether impulses. It recognizes but seven different colors or color groups in the solar spectrum. There is no sharp line of separation of these colors from one another. FIG. 115. Dispersion of light as it enters at D, and again as it leaves a falling raindrop at V'R'. The internal reflection of this light at RV rather than its transmission through and beyond the falling drop makes possible a rainbow in the east when the sun is in the west in late afternoon. (Tower, Smith & Turlon.) The great variety in colors coming from bodies results from the blending of different wave lengths in different proportions, giving rise to color sensations of a composite character. It is quite possible that there are other forms of energy transmitted through the ether medium unrecognized by man because of a lack in his own body of any "receiving apparatus." Advances in science may, however, succeed in arresting and so transforming any such forms that their existence and nature will become apparent. Wireless teleg- raphy, and the use of the dynamo for the production of electric cur- rents, are illustrations of the uses made by inventors of the discoveries of scientists. The discovery of "X-rays" and of radium, and the 348 GENERAL SCIENCE applications already made of these advances in scientific knowledge, suggest that much is yet to be learned about forms of radiant energy. If objects reflected all the light incident upon them their colorings would be wholly dependent upon the kind of light that came to them. However, it is found that varied proportions of the different wave lengths are absorbed into bodies upon which they fall according to the material in the bodies. This phenomenon, known as selective absorp- tion, results in color waves being reflected from a body that may be entirely unlike those which fell upon it. Color then in some cases actually does become a characteristic of bodies, indicating the presence in them of certain kinds of matter. Exercises 1. In the formation of rainbows where must the dispersion occur? Explain how it is that the dispersed sunlight gets back to the observer from the part of the sky where the bow is. 2. Account for differences in color of the adjacent parts of petals of flowers. 3. Why are upper cloud masses of an advancing thunderstorm often silvery white in appearance, while the under surfaces of the same clouds may be inky black? 4. Distinguish between reflection, transmission, and absorption of light. Since ether waves may be transmitted through bodies, what must be true of the existence of an ether medium within them? 6. Why are heat and light said to be forms of energy? By what means are both supposed to be sent on (propagated) through space? Distinguish between sight and light. XV. THE EARTH AS A PLANET DAY AND NIGHT, AND THE EARTH'S ROTATION It is not strange that the ancients believed the earth was the center around which the sun, moon, and stars revolved, or that from the time of Ptolemy (A. D. 100-170) to Coper- nicus (1473-1543) it was taught that the earth was the centre of the universe. In these days we believe that the earth's rotation accounts for the daily round of the heavenly bodies as they rise, pass meridian, and set. But it is neces- sary to make a more or less conscious effort really to think in terms of the Copernican rather than of the Ptolemaic teaching. The very language we use tends to preserve the older views. We say that the sun sets, the moon rises, etc., and we fail to devise any better expression of our meaning. It is not wholly a misfortune, however, that so much of mental effort has to be made to distinguish between what is real and what is apparent in the phenomena occasioned by the earth's rotation. In the study of Astronomy there are ever recurring demands actually to "see" (to visualize) mo- tions of celestial bodies in space that are similar to those of the earth. The development of an imagination based upon known realities, and of a power to grasp abstract mathe- matical notions, is of greatest educational importance. If the earth as a spherical body were to become fixed in space (to stand still), then for an observer at any one place all objects above his horizon would remain in sight all the time, and objects below that horizon would always be hidden. In case the observer were to travel about, his horizon would change with the place of observation. New bodies would come into view as his horizon dipped below them in whatever 349 350 GENERAL SCIENCE direction he advanced, while others at the same time would be passing out of sight below the opposite horizon (the direc- tion from which the observer is moving). If, on the other hand, an observer remains at the same location, and is carried round and round by reason of rotation of the earth, the same phenomena of the rising and setting of celestial bodies is experienced. Why the rate of the earth's rotation is what it is must remain unknown. But this rate is uniform, and its period for one rotation is the natural time unit known as a day. The rate of rotation so far as known varies for the different planets, and their day periods differ somewhat from ours. The whole of the earth's surface moves on together in its motion around the axis. Those portions at and near the equator, which have a much longer circumference to be carried through in the same time of rotation, must have a correspondingly greater eastward velocity. Near the poles the number of miles through which any position on the surface must be carried to make a completed round of motion is less, and the eastward velocity there of the earth's surface is relatively small. Because of the earth's spherical form, as an observer travels northward his northern horizon dips lower and lower. The North Star, which at the equator is approximately upon the horizon, seems to rise higher and higher as he advances northward. Its altitude (distance above horizon) is for him all the time the same as his distance from the equator (his latitude). Both the altitude of the star, and the latitude of the observer, are expressed in degrees. SUMMARY The rising and setting of the sun, moon, and stars is a direct result of the rotation of the earth. As the earth in its rotation carries us as observers around on its surface, our eastern horizon passes star after THE EARTH AS A PLANET 351 star in turn and moves on beyond them. This causes them to seem to rise and pass across the sky. In due time our western horizon passes them shutting them from our sight, and we say that they have "set." In like manner the earth's rotation brings the sun above the horizon of an observer, causes it to pass across the sky, and then to disappear from view as the western horizon passes it. Thus day and night as periods in which the sun is above or below horizon follow each other in endless succession, and will continue to do so as long as the earth continues to rotate. Places at the equator are carried eastward by the earth's rotation at the rate of over one thousand miles per hour. This velocity lessens toward the poles where it has a zero value. Directly related to these rotation rates are the directions of the great atmospheric and oceanic currents. It is because of the rotation of the earth that we have a basis for use of the terms axis, poles, equator, and parallels of latitude in connection with earth studies. ROTATION COMBINED WITH REVOLUTION, AND CHANGES IN SEASONS It is difficult for one who lives in the middle latitudes to realize what is true of seasonal changes in the far north or in the Torrid Zone. Experiences gained through travel assist in comprehending them. ,To understand the revolution of the earth about the sun, whether studied in Physical Geog- raphy or in Astronomy, requires more than mere reading about it. Long sustained observations of celestial phe- nomena as " studies of the sky" when intelligently pursued afford a good basis for such an understanding. The lessened meridian altitude of the sun at noon-time, from June to December, and the consequent increase in obliquity of the sun's rays, is accompanied by lessened heating effects day by day. But the lowest temperatures of the season occur later than December because of the cumula- tive losses in solar heating. Accompanying these changes are shortened periods of sunshine (shorter "days"), intensifying 352 GENERAL SCIENCE the results of a lessened insolation and of the ever increasing losses of heat by reflection as the angle of obliquity increases. The daily path of the sun rises continually higher in the heavens from December to June, the sun rising farther and farther north, crossing the meridian higher and higher up from the south point of horizon, and setting farther and farther north. This makes an ever enlarging diurnal circle b' FIG. 116. Diurnal circles of the sun at different seasons: axa', at summer solstice (June 21); bzb', winter solstice (December 21); EyW, vernal and autumnal equinoxes (March 21, and September 21). dd' is the diurnal circle of a star which for an observer in northern latitudes never rises nor sets, i.e., a star always above horizon. above the horizon, and longer and longer daytimes. Upon these changes in obliquity of the sun's rays, and upon the duration of the periods of sunlight, depends the changes of seasons. These changes are scarcely considered from day to day, and less frequently are they given their real significance in terms of the revolution of the earth about the sun. When one looks out toward the sun at any time, it is difficult to realize that the distance between the earth and the sun is approximately the enormous value of 93,000,000 miles. So distant is the sun from the earth that of the heat given off by the sun only about one two-billionth part is received by the THE EARTH AS A PLANET 353 earth. Yet great as is this distance, the earth in six months time will be at an equal distance on the other side of the sun. In other words the earth will have traveled about half way around in its orbit. When one calculates the number of miles in half of the earth's path about the sun, and divides the result by the number of minutes in six months of time, it is not surprising to find that the earth's velocity in its orbit is about one thousand miles per minute. This is about a thousand times faster than the swiftest express train. In this revolution of the earth about the sun it must be kept in mind that the moon accompanies the earth in its advance. The earth is at all times in rotation as it moves on, and the moon is all the time revolving about the earth as a centre. Though the rate at which the earth moves varies considerably in different parts of its orbit, the time period for complete revolutions is of unvarying length, and it constitutes the natural time unit known to us as the year. In this year period there are about three hundred sixty-five and one-fourth days. In the arrangement of days into months to make up the calendar it has been necessary to let every fourth year 1 contain 366 days, February then having in these "leap years" twenty-nine days. The times of changes of seasons are thus made to occur on the same dates every year. The periods of revolution of the other planets or their " years" vary widely, depending upon their distances from the sun. Mercury, the innermost of them, gets around in about eighty-eight of our days, while Jupiter requires twelve and Neptune one hundred sixty-five of our years. SUMMARY The paths of the sun across the sky are not the same day after day. It is a matter of common observation that from June to December the 1 An exception to this is that the first year of each new century as 1800, 1900, 2000, etc., is a leap year only when divisible by four hundred. 23 354 GENERAL SCIENCE sun rises farther and farther south on the eastern horizon, is lower and lower down from the zenith at noontimes, and sets farther and farther south on the western horizon. From December to June these changes are in reversed order. The duration of the sunlight period, i.e., the length of the days 1 , varies with these changes. In the northern hemisphere the longest days are in June when the sun's path across the sky is highest up toward the zenith, and the days are shortest when those "diurnal circles" are lowest down toward the south. This is due to the progress made by the earth in its revolu- tion about the sun. The observer is brought into new positions in the earth's orbit day by day from which to look out toward the sun as the earth's rotation brings him around on the daylight side. Upon the duration of the period of sunlight, and upon the obliquity of the sun's rays for any observer, depends the amount of solar heat received by him, and the changes of seasons for that locality. The year as the period of the earth's revolution, and the day as the period of the earth's rotation, are natural time units of unchang- ing values. It is true that the earth's velocity in different parts of its orbit varies, but the length of the year period does not change. The earth is "on time" so far as completion of its journeys of revolution are concerned. The lengths of the times from passage of the centre of the sun's disc across the meridian of any observer till it is next on meridian vary a little at different times of year. This necessitates the use of an imagi- nary day known as the "mean solar day." Its length is the average of the lengths of all the solar days of a year. Our clocks and watches keep mean solar time. Exercises 1. Why do we experience so much difficulty in realizing the fact that we live upon a rotating earth? 2. What is meant by (a) horizon; (b) sunrise? 3. Since the daily paths of the stars across the heavens, i.e., their diurnal circles, result from the earth's rotation, and since the direction of the earth's axis is at all times parallel to itself and always points toward the same place in the heavens, what must be true of the relative positions of the diurnal circles (a) of different stars; (b) of the same star? 1 It usually is possible to distinguish from the context whether the word "day" has reference to the period of the earth's rotation (24 hours), or to the duration of daylight (not night-time). THE EARTH AS A PLANET 355 4. Distinguish between rotation and revolution for the earth. What is meant by the orbit of the earth? 5. How much nearer the sun is the earth in our winter season than in summer time? What is true of the relative lengths of the times of revolution of the earth, i.e., of the lengths of the years? What does this argue of the averages of the earth's velocity in its orbit, and of the extent (length) of that orbit year by year? 6. Why are those circles of the earth known as the Tropics located 23^ on either side of the earth's equator rather than some other distance? 7. Account for eclipses (a) of the moon; (b) of the sun. 8. The diameter of the earth is 8000 miles; of the sun 880,000 miles. How many times greater volume has the sun 1 ? 9. What is the cause of the varying obliquity of the sun's rays as found in the lesson on Solar Heating? THE MOON, AND ITS PHENOMENA It is in the changing phases of the moon, and in its varying angular distances from the sun, that we can actually see the revolution of one celestial body about another. The moon is only 240,000 miles from the earth, a small distance in the scale of the celestial sphere. In its revolution about the earth the moon comes in between earth and sun (though seldom in a direct line), and moves on away from the sun farther and farther as measured in degrees along the curved background of the sky. When it is on the side of the earth opposite the sun, and 180 from it, an observer on the earth sees the side of the moon that is illuminated. Then as the moon continues in its path around the earth it approaches closer and closer to the sun as seen from the earth till once more it is on the same side as the sun. The dark side of the moon is then toward the earth. The moon has no light (or heat) of its own. There is an abiding satisfaction in being able definitely and quickly to grasp the relationship of sun, moon, and earth in space as the moon's form and its position relative to the sun are noted. It makes an excellent preparation for 1 The volumes of spheres are to each other as the cubes of their diameters. 356 GENERA SCIENCE any later studies in Astronomy. In estimating distances in degrees on the surface of the sky, it is helpful to remember that from the south point of the horizon to either east or west points, or to the zenith, is 90. The diameter of the full moon is about J^, and the distance between the "pointers" in the bowl of the "Big Dipper", by means of which the North Star is readily located, is about 5. The full moon is always on the side of the earth opposite the sun. In winter-time the sun rises far to the south of east, and sets far to the south of west. This is because the north pole of the earth is then tipped away from the direction of the sun. It follows that the rising of the full moon at sunset will be far northward of the east point of the horizon. By reason of the earth 's motion of rotation the diurnal circle of the full moon then will be high up in the heavens, and down to a point of setting far northward of the west point of the hori- zon. This occasions the long and very bright moon-lit nights of midwinter. These are in marked contrast with those of summer when the path of a full moon across the heavens is much lower toward the south, and the light of the moon much less intense because of the greater obliquity of its rays. To attempt to reason out what must be true of natural phenomena such as these requires always the check of actual observation at every opportunity till one is assured that his conclusions accord with the facts. Acquiring a clear understanding of the phenomena presented in the changing positions of the moon, and verifying one's concep- tions by repeated observations, enables one to catch some- thing of the spirit of the scientist as he seeks to master what has hitherto been unknown. In many respects the moon itself is an uninteresting sub- ject for study. Astronomers have been unable to detect any evidences of life upon it, or to note there the physical condi- tions essential to life like that known here on the earth. THE EARTH AS A PLANET 357 There is no atmosphere, no water, no protection from the intense solar heating. For two weeks at a time the sun shines continuously on the same places. There are no clouds in the sky to prevent radiation of this heat, and it must become extremely cold through the two weeks of continuous absence of sunshine that follows. A lunar landscape lit up FIG. 117. A portion of the moon's surface as seen in a telescope. Note the shadows cast by mountains, and others within the craters of lunar vol- canos now extinct. The sunlight is from the left side. by the sun's rays in such a way as to throw into shadow reliefs the rugged mountainous surface of the moon is, how- ever, a most interesting sight when viewed through a good telescope. Photographs of the moon's surface when made by aid of the telescope give a good idea of what the astronomer beholds. Our moon has a diameter of about two thousand miles, or one-fourth that of the earth's diameter. Its volume then is approximately (J^) 3 or J^ 4 that of the earth. Its weight, however, as calculated by astronomers is but J^o of that of the earth, showing that the material of which the moon 358 GENERAL SCIENCE is composed has less density than the earth. How it is that astronomers calculate the masses of the planets and their satellites, their volumes and their relative densities, is exceedingly interesting to those who have considerable knowledge of mathematics. While the earth has but the one satellite or moon, Jupiter has nine, and Saturn nine or ten. Some of these have been discovered only within recent years. SUMMARY In the changing positions of the moon relative to the direction of the sun from the earth we can actually see the moon's revolution about the earth. This change in distance of the moon from the sun must be measured in degrees upon the curved surface of the sky. As the moon moves on in its orbit its illuminated side as lit up by the sun is at times toward the earth. It then appears as a "full" moon circular in outline. At other times the dark side is toward the earth, while the crescent and gibbous phases are views of but portions of the illuminated spherical surface. The change in extent of the sun- lit side visible from the earth varies chiefly by reason of the moon's changes of position in its orbit. Lack of water and of atmosphere, and a probable extreme range in temperature from a time of two weeks of continuous sunshine to a two weeks' absence of sunlight, makes it unlikely that any forms of life such as are known here on earth can exist on the moon. The duration of the hours of moonlight, and the variation in its in- tensity, depends as with sunlight upon how high up toward the zenith of any observer the diurnal circles of the moon are. In this northern hemisphere it is in the winter time that the full moons "run high" in the heavens, and long bright moonlight nights occur. While the crescent moon as seen in the west at sunset is to the east of the sun, and the crescent moon seen in the morning before sunrise is to the west of the sun, it does not follow that the moon has passed the sun and changed sides with regard to the sun. Such a change does occur at the "dark of the moon," and just before "new moon." In the former case what has occurred is that the waning crescent of the "fourth quarter" is coming nearer and nearer to the sun, both its THE EARTH AS A PLANET 359 distance and its direction now being measured from the opposite edge of the surfs disc. Easter is the first Sunday following the first full moon that occurs next after the Vernal Equinox (time in the spring when the days and nights are equal). TIME, AND TIME-KEEPING, AND STANDARD TIME Time-keeping resolves itself into a choice of convenient units as subdivisions of natural time periods, and the use of devices for counting and registering these smaller units with an unfailing accuracy. Since the time of Gal-i-le'-o (1564-1642) use of the vibration periods of pendulums (or those of coiled springs in watches) has displaced the hour- glass and other devices of the ancients for measuring time. They had the years and the days for large time units the same as we, but accuracy in the measurement of smaller time units waited upon the discovery of the laws of the pendulum. It is quite indispensable that the time-pieces of a com- munity its homes, shops, factories, mills, and schools shall be so set and regulated that they show at all times the same readings. Railway service in all parts of any section of the country requires the same time standard by all con- cerned in its administration, and travelers must adapt their times to this standard. Since the earth rotates through 360 of circumference in twenty-four hours, its rate of rotation is 15 per hour. Any place 1 5 eastward of an observer has noon by the sun (that instant when the sun's centre is on the meridian of the place) just one hour earlier than noon with the observer, or four minutes earlier for every i of distance. Places westward of the observer have their meridians come to and pass the sun four minutes later for every degree farther westward. Observers living east and west of one another will have different "local time" whether their time-pieces are kept 360 GENERAL SCIENCE with it or not. It is more convenient, and in all ways more practical, for all the people in any certain section of country to have all time-pieces read twelve o'clock when it is noon at places situated on some one geographical meridian chosen as a standard. By having these standard meridians 15 apart the time-pieces in adjacent time-belts will be exactly one hour apart. A traveler going from one such section into another will change his watch reading just one hour at some convenient or established place, leaving the readings of the minutes and the seconds unchanged. If the traveler jour- neys eastward, his watch is set ahead an hour for every change from one time-belt into another in order that its readings may conform to the time of the belt into which he has come. In going westward the watch must be set back an hour each time. It is interesting to note what befalls a traveler in the matter of time-keeping who makes long journeys east or west around the earth. If changes of one hour at a time are made from time-belt to time-belt as discussed above, the watch readings will conform always to the times of the places where the traveler may come. But confusion soon arises as to what day in the week it is. The day period from noon to noon (or midnight to mid- night) is lengthened in going westward. The traveler has need to set his watch back one hour for every 15 passed over, and while the time at the place whence he started might show one whole day passed, the traveler's watch after being set back shows but twenty- three hours passed. He has "lost" an hour. To travel 30 westward means a read- ing at the place where the journey began two hours later than at the place where the traveler then is, or two hours lost. To complete the 360 of the earth's circumference and the twenty-four changes of watch that this requires involves the loss of one whole day. In other words, at the THE EARTH AS A PLANET 361 place where the journey began there has been recorded twenty-four hours or a whole day more of time than has been counted by the traveler with his repeated "setting back" of his time-piece. He is a day behind the calendar upon his return. While his watch reading is in accord with the time at the starting place, his day of the week is made right only by passing over one day in the calendar. If his return is on Tuesday evening by his reckoning, then he must consider the next day Thursday. As a matter of custom this jumping over one of the days of the calendar is done by west bound travelers when crossing the Pacific Ocean, and when near the so-called international date line. To travel eastward involves a similar series of changes and adjustment of days. But in this case the watch must be set ahead an hour at a time, and at the international date line two days in succession have the same name. There has been a day gained by the traveler, and his calendar is a day ahead of the places to which he comes, making it neces- sary to live one of his days over again so far as the name of the day is concerned. Each new day upon earth may be considered as having its beginning at this international date line, and as traveling around the earth westward. When this same day is just be- ginning at places on that side of the date line to reach which the day "has traveled around the earth," it is twenty-four hours old on the beginning side of the line. The whole earth will then be covered by the same calendar day. But at that very instant the next succeeding day is beginning on the "east side" of this imaginary line to pass on in turn around the earth, while the preceding day is growing older and finally is to pass off from earth when the new day in turn comes to the "west side" of the date line. It is not so strange as at first it may appear that news- papers, with headlines that tell of startling events in Europe 362 GENERAL SCIENCE or the Far East, are on sale in cities of the United States at hours in the day earlier than these events are said to have occurred. Telegraphic transmission of news has out-stripped the earth's rate of rotation, and the differences in time of the continents gives ample opportunity for publication of the news apparently "before it happened." To visualize such conditions as these, and to be able concisely to express in detail these relationships of time-keeping over the world, is a worthy test of one's ability to think clearly and surely to conclusions based upon involved data. SUMMARY The calendar as a system for time-keeping makes use of the periods of rotation and of revolution of the earth the day and the year as un- changing time units. Shorter units are obtained by an arbitrary divi- sion of the average length of solar days into hours, minutes, and seconds. Pendulums and springs, by proper adjustment of their lengths, may be made to vibrate at an unvarying rate of once per second, or any other short period desired. By means of wheelwork the number of these vibrations can be shown on a dial as so many hours, minutes, and seconds past noon or past midnight. A ready means of remembering the relative times of places east and west of one another is to recall that "east clocks are fast clocks," the noons of places east occurring earlier than at places west of them. To travel west with the sun has the effect of lengthening the day of the traveler, so that in going around the world he has had one less number of days in that period of travel than has another person who has re- mained at home. The traveler has "lost a day," and somewhere on his journey westward must drop a day from his calendar. In journey- ing eastward around the earth the traveler's days are shortened as he goes to meet the sun, and as the result he has gained a day in making a journey around the earth. It thus becomes necessary somewhere in the journeying to have in succession two days of the same name, i.e., to set his calendar back a whole day. " Standard time" is a system of time-keeping whereby the clock readings throughout a whole section of country are the same regardless of the actual time at these different places as indicated by the sun. THE EARTH AS A PLANET 363 All time-pieces are set to read noon throughout the time-belt when only the places on a certain meridian running through the central portion of this region really have the sun on meridian. While in theory these time-belts are seven and one-half degrees of longitude in width on both sides of each of the time meridians, as a matter of fact there are great departures from any such arrangement to conform to the convenience of the traveling public. Sunrise during the Spring and Summer is so much earlier than the hour fixed by custom for starting the wheels of the nation's industries that in many ways it is advantageous to have the industrial day for people generally begin at six o'clock rather than at seven A. M. This makes the mid-day meal come at eleven instead of twelve o'clock. Many difficulties, both civil and legal, would be involved in any change in the hours established by custom and by statute for beginning and closing the varied activities of life's affairs. Instead, a "Daylight-Saving Plan" now followed in the United States and in other countries decrees that at a certain date in the Spring all clocks shall be set ahead one hour, and then set back one hour at a fixed date in the Fall. The round of daily activities during the Spring and Fall then actually begin one hour earlier every day and close one hour earlier at night than during the other part of the year. But the times as shown by the clock remain the same the year around. During the Summer under this plan the sun is yet an hour's time from meridian when the clock reads noon. People order their ways of life by clock time rather than by sun time. XVI. THE HEAVENS "The heavens declare the glory of God, and the firmament sheweth his handiwork. Day unto day uttereth speech, and night unto night sheweth knowledge. There is no speech nor language where their voice is not heard". Ps. XIX: vv. i, 2, 3. Poets and philosophers in all ages have gained inspiration as they have contemplated the heavens, and striven to formu- late and express the thoughts of the Infinite to which these studies have given birth. Early literature contains number- less allusions to astronomical myth and fact. To catch the subtle meaning of many a passage of literary excellence re- quires some acquaintance with Astronomy. A knowledge of high school physics renders comparatively easy the read- ing of books on general astronomy. But one does not need to be an astronomer in order to know something about the universe outside the earth, and to com- prehend something of the significance of what is visible to him of the celestial sphere both by day and by night. Not only may a person become more appreciative of the beauty of the sky as apparently it moves in ceaseless round above him, but some definite knowledge of what is seen enriches and stimulates his intellectual life. An intimate knowledge of plant growths by field and forest and stream makes life more enjoyable to us; intimate acquaintances among people gives pleasures to life which no crowds of those unknown to us and to whom we are indifferent can give. So an acquaintanceship " amongst the stars" yields an ever- increasing pleasure as the years go by. To be an astronomer onfc must become skilled in mathematics; but there is avail- able to every one in the realm of Astronomy a vast fund of 364 THE HEAVENS 365 quickening non-mathematical knowledge of an elementary character. So vast are the values for time, space, and size in the celes- tial sphere, values that approach the infinite in their magni- FIG. 1 1 8. Constellations of the northern heavens always above horizon in most parts of the United States. tude, that the human mind must resort to comparisons involving enormously large units in many cases. Only a few of the more serviceable of these numbers need be remem- bered, and these only as approximate values. The velocity of light, 186,000 miles per second 1 , serves the astronomer as 1 The velocity of sound is only a little more than one-fifth mile (noo feet) per second. 366 GENERAL SCIENCE a convenient substitute for a yardstick. This velocity of light is so great that to encircle the earth (25,000 miles) it would require but one-seventh of a second. To reach the earth from the moon (240,000 miles) light requires some- what more than one and one-fourth seconds, and from the sun (93,000,000) somewhat more than eight minutes (499 seconds). It is interesting to compute the number of miles light travels in one year in view of the fact that astrono- mers calculate the distances of the stars as so many "light- years" from the earth. From the star believed to be nearest the earth we are told it requires light more than four years to reach the earth; from Sirius the "Dog Star" that is so conspicuous in the southern sky in a winter evening more than eight years ; from the North Star about forty-seven years; and from those stars most distant, and yet visible on photographic plates made by aid of the telescope, perhaps many hundreds of years. When we consider that a star whose light we are still getting that we still "see" may have been blotted out of existence unnumbered years ago, something of the extent of the Universe is borne in upon the human mind. The number of the stars, while not at all a " countless multitude," is nevertheless so great as to cause amazement when we think of them as light-giving bodies like our sun. The number visible to an observer with the naked eye only at any one time and place is perhaps less than .two thousand, or about five thousand in the whole heavens since many just above the horizon are not readily seen. But the number of stars that may be counted on photographic plates of the whole heavens as made by use of the largest telescopes is perhaps several hundred millions. In an exercise of the imagination based upon such facts as these, and that is at all times in accord with facts, there is developed the noblest THE HEAVENS 367 "to think the powers of the human mind, enabling man thoughts of the Almighty after Him." Perhaps the readiest way in which to recall at any time the relative distances of the planets from the sun is to make use of the following device known as Bode's Law: Name Mer- cury Venus Earth Mars Aster- oids 1 Jupi- ter Saturn Uranus Nep- tune Symbol 5 9 e T 76, 208, 235 Dissipation, 71, 73, 80 Distillation, 93 natural, 94, 106 Diurnal circles, 148-149, 350-351, 354, 356, 358 Drowning, 23-24 Drugs, habit-forming, 75-80, 82 Dwellings, 206-209, 218 Dynamo, 168-172 Earth, the, 157, 193, 349-3 54 Easter, 359 Eclipses, 337-338 Economic conditions, 281-296, 327 Education, 17,80-81, 210-212, 257, 284, 293-294, 298, 349 Efficiency, 31-32, 65-69, 72-75, 83, 163, 167, 207, 211-213 Eggs, 279, 299-303 candling of, 301 preservation of, 301-303 Elasticity (and plasticity), 155 Electric lights, 218-219 Electricity, 168-172, 184-190 Electrolysis, 184-190 Electromagnets, 168-172 Electro-plating, 170, 185-186, 190 Embryo, 302, 315 Emergencies, 233-239 Emetic, 234 Emulsion, 177, 179, 310 Energy, 160-163 electrical, 1 68, 172, 190, 218 molecular (and heat), 143, 147, 161, 218 of ether motion, 346-347 of the human body, 26-27, 29, 31, 40, 67, 134 solar, 161, 217 in relation to plants, 268, 274 transformation of, 160-161 transmission of, 160-163 Enzymes, 174-175, 231 Equilibrium, 165, 167 Erosion, 103-108, 333 Ether medium, 144, 162-163, 172, 218, 344-348 absorption of motion of, 147, 162 wave frequency in, 162 Evaporation, 86 Evolution, plants and animals, 302, 305 Exercise, physical, 31, 36, 65-69, 72^ J75, 241 Exercises (see Questions). Expansion (see Volumes of bodies coefficient of, 141-142 Eyes, and their care, 10-15 parts of, lo-n Eye-strain, 12-15 378 INDEX Faraday, 168 Feathers, 276, 297 Ferments, and fermentation, 6, i7S Fireless cooker, 145 Fires; 235-236, 239, 254-256 Flame, 17-18, 235-236 Flies, 57-60 Flowers, 265-266, 315 Food inspection, 47-49, 51 Foods, classes of, 27, 222-224 quantity needed, 219-220 Food stuffs, 45-48, 209, 220 adulteration of, 48, 226 composition, table of, 225 Forces, 151, 155, 157, 160, 163 Forests, 254-258 Friction, 154 Frost, 92, 94 Fruit, 262, 267 Fuel, 214-217 Fungi, 322-325 Fusion, heat of, 95-96 Garbage, 61 Garden, 241-246 Gases, 86, 98-99 liquefaction of, 116-118 pressure of, 117-118 temperature due to compression and expansion of, 90, 117- 118, 125, 138 Gasoline, 177, 235 Gluten, 300, 327-328 Gravity, and gravitation, 155-158, 338 Growth, 64, 71, 83, 302, 315-316 Gypsum, 195 II Habit formation, 74-76, 80-84, 219, 295 Hand, structure and uses, 2-3 Headache powders, 77 Health, i, 29, 31-36, 42-43, 49, 5$, 61-69, 72-74, 208-209, 219- 221, 223-224, 237, 241, 293 in relation to weather, 113, 133- 137 Heat, 116-117, I43-I47 and electricity, 161, 218 as molecular energy, 143-144, 161 conduction and convection of, I43-I4S liberated by condensation or compression, 95, 117 measurement of, 94-95 of solution, 99 of vaporization, 95-96 radiation of, 144-145, 147 reflection of, 149 solar heating, 112, 149, 35i~352, 367 specific heat, 87 Heat equator, 131 Heavens, the, 364-369 "Highs" and "lows," 129-131, 137- 140 direction of their movements, 129-131, 138-140 Homes and their surroundings, 206, 214-215, 245-246, 283 heating and lighting, 214-215, 218-219 rooms and their furnishings, 206-208 Horizon, 147-149, 349~35* Horse, 304-307 Humidity, 20, 93-94, 136-137 Hygiene, i, 25, 32, 35-36, 42-43, 65- 69, 72-79 Hypothesis, 98, 101 INDEX 379 Ice, 50, 116 density of, 88 Images by reflection, 338-342 how located, 340 Immune, 36-37 Incandescence, 18, 217-218 Industrial life, 281^-290 Industries, chemical, 188-192, 195, 199-203 iron, 197-204 petroleum, 284-287 relation to coal supply, 196-199, 216 Inertia, 154 Infection, 36-54, 61, 208, 236 Initiative, 2 43 Insects, 57-62, 278 Instinct, 277-278 Insurance, 235, 239 Intemperance, 66, 69 Ions, and ionization, 181-183, l86 > 190 Iron (and steel), 197-204 cast iron, 92, 201-202 galvanized, 203 pig iron, 201, 204 properties of, 201-202 tempering of (as steel), 203-204 uses of, 196-197, 202-204 Irrigation, 105, 108, 244, 247 K Kerosene, 17, 235, 286 Knowledge, 83-84, 210 Labor, 281-284, 288-289, 292-295 on farms, 327-328 Laws, of correlation of forces, 1 70 of definite proportions, 16 Laws, of gravitation, 155-156 of life, 68 of machines, 167 of science, 98 of "survival of the fittest," 265, 279 of weather, 137 Leaves, 262, 264, 267, 270 Levers, 163-167 Life, 64-68, 71, 78, 356 Light, diffusion of, 179, 341 in relation to heat, 217-218, 346 phenomena of, 336-348 reflection of, 339~34i, 344 refraction of, 341, 343 velocity of, 337 Lime, in water, 178-180 for builder's uses, 191-192, 195 Liquids, 86 Literature, relation of to science, in, 242, 258, 364 Litmus, 180-182 Lumber, 255-256 Lungs, and their capacity, 22, 25 Lymph, 71-72 M Machines, 163-164, 166-167, 169- 170, 196, 239, 284-285, 288, 295 for farm uses, 310, 327-331 the human body as a machine, 26, 29, 66 Magnetism, 170-172 Malaria, 38, 6 1 Mammals, 305-306 Manhood, 81-83 Marble, 193-194 Mass, 152, 155-156 Matches, friction, 176 Matter, 151-158 indestructibility of, 152 living matter, 151-152 properties of, 152-155 3 8o INDEX Medicines, purpose of, 33-36, 65, 78 Mercury, boiling and freezing tem- peratures, 142 coefficient of expansion, 141 properties of, 141-142, 146-147 Metabolism, 174-175 Metals, 188-189, 194-205 importance of, 196-197 Milk supply, 226, 308-311 pasteurization of, 309 Mind, 8-9, 65-66 Molecules, 85-86, 173-174, 181 Moment, 165-167 Momentum, 166-167 Moon, 157, 353, 355-358 number of moons for other planets, 358 phases of, 355, 358 physical characteristics, 357-358 Mosquitoes, 39-40, 6c-6i Mouth, 4-6, 8-9 connected parts, 4-5, 9 Narcotics, 73-79 Natural resources, 103-105, 107, 218, 254-256, 284-287 Nerves, 2-3, 5, 8-9, 31, 33, 79 nerve shock, 236, 239 Nitrogen, 112-113, 2 57 Obliquity of solar rays, 147-149, 351- '352 Oils, 231, 272-273 Ores of the metals, 194-201 Osmosis, 99-101 osmotic pressure, 100 Oxidation, 16-18 Oxygen, 16-18, 175, 226 liquid oxygen, 117-118 Pain, n, 33, 35 Paint, 203, 208, 272-273 Paper, 273-274 Parasites, 40 Pasteur, 36, 39 Patent medicines, 76-77, 79 Pendulum, 359, 362 Perspiration, 27-29 Petroleum, 284-288 Phenomena, 152 Planets, 337~338, 353, 367-369 Plant growth, conditions for, 243, 247-251, 253 Plants, studies of, 263-274 flowers, 265-266 leaves, 263-265, 267-270 propagation of, 266-267 roots, 243-244, 248-249, 263, 267 seeds, 265-266 usefulness of plants, 255-259, 263-265, 268-274 Play, 69-71 Pollen, 265-266 Potato, 229 Poultry, 297-303 structure of bodies of fowls, 297-298 Poverty, 73, 212-213, 290-291 Preservatives, 47-48, 51, 307 Producers, 281-283 Proteins, 27, 220, 222-225, 231, 299- 300, 328 test for, 301 Protoplasm, 64, 71, 79, 222, 226 Protosynthesis, 228 ^ Protozoa, 36-38, 40 Ptomaines, 41, 47 Public health, 47-51 Pulleys, 164 Pumps, 122 Pure foods, 48, 51 Q Quarantine, 43, 45 Questions, lists of, 15, 30, 51-52, 63- 64, 84, 97, 101, 108-109, 123, 131-132, 140, 150, 158-159, INDEX Questions, lists of 163, 168, 172, 180, 213-214, 232-233, 239-240, 247, 254, 259, 275, 280, 289- 290, 303-304, 307, 312, 3i7- 318,329-332, 348, 354-355 Rainfall, 90-92, 94, 136, 138-139 Rats, 61-63 Recreation, 68-72 Refrigeration, 118, 145 Resistance, 154, 164, 167 Respiration, 19, 24, in Rest, n, 66-72 Revolution of earth, 148, 154, 157, 351-355 "leap year," 353 lengths of years, 353 velocity of, 353 Right living, 65-84, 207-208, 211- 213 Rocks, 334-335 limestone (see Gypsum), 192- 196, 202 sandstone, 194 stratification of, 192-193 Roots, 243-244, 314 Rotation of earth, 128, 131, 349-351 rate of, 350-351 "Safety first," 238-239 Saliva, 6 Sand, 247-248 Sanitation, 46-51 Schoolrooms, conditions in, 13-14, 20-21, 23, 41 Schools, purposes of, 26, 42, 49, 51, 68, 80-82, 84, 207, 2 1 1-2 1 2, 252, 257, 292-296 Science, achievements of, 284, 289, 295 Seasons, 351-354 Seeds, 265-267 Serums, 37, 41, 45 Sewage, 56 Shadows, 336-33?, 357 Sickness, 32-33, 35, 42, 57, 65, 74, 175 by inheritance, 32 treatment of, 33 Silos, 316 Sleep, 19, 25, 32, 66-68, 72 Soap, 177-178, 19 Social welfare, 41-43, 46-49, 61-62, 69-71, 74-75, 287-288, 290- 295 Soda, manufacture of, 190-191, 195 Soils, 247-254, 332-335 classes of, 247-248, 251, 332-333 fertility of, 251, 313 humus in, 251, 333 origin of, 333~335 sorting of by water, 333 temperature when water-soaked, 96 tillage of, 243, 246, 248-254 water content of, 248-249 Solar heating, and obliquity of rays, 142-149 Solar spectrum, 342-347 Solids, 86, 98 Solutions, 88-90, 98-99, 101 Specific heat, 89, 146-147 Spectrum analysis, 345-346 Sports, 70 Sprains, 3 Sprays and spraying, 122, 321-323, 325 Standard time, 359-363 Starch, 222, 226 -229, 231, 317, 328 Stars, 366, 368-369 Sterilization, 45, 234, 236, 311 Stimulants, 72-99 Storage batteries, 120, 187 Strain (and stress), 154 INDEX Streams, 103, 106 Sublimation, 92 Submarines, 119-120 Sugar, 222, 224, 227-231 Sun, 351-354, 367-369 atmosphere of, 337~338 distance of, 352-353 Teeth, 8, 10, 277, 305-307 Telegraphy, wireless, 172 Temperate living, 67-70, 73-74 Temperature, 86, 140-147 boiling, and freezing, 86, 99, 146 in relation to volume, 140-141 of human body, 27-29 Tempering, 203-205 Tenacity, 155 Tendons, 2 Theories, as to light, 338-339, 344~ 347 in astronomy, 337 of conduct, 293-295 of education, 294, 296-29; of science, 71, 152, 160, 162, 181-182, 186 Thermometers, 140-142, 146-147 clinical, 35 Thermos bottle, 117, 145 Thrift, 134, 209-213, 235, 290-203 Timekeeping, 359-363 international date line, 361 local time, 359 standard time, and time belts, 360-363 Tobacco, 74, 79, 211 Tonsils, 5 Tornado, 125-127 Toxins, 40-41, 45 Transpiration, 270, 314 Transportation, 53, 85, 281-283 Trees, 254-263 planting, and uses of, 256-259 studies of, 259-263 Tuberculosis, 25, 39 Typhoid, 37-38 V Vaccination, 37-38 Vaporization, 90-96 heat of, 94-96 Varnish, 273 Veins, valves in, 34 Velocity, 157, 337, 350-351 Ventilation, 20-21, 23-25, 122 Volumes of bodies, changes in, 20, 88, 93, 116-124, 141-142, 146- W Wage earning, 283-284, 290-291, 295 Washing powders, 178, 191 Waste, 26, 29, 32, 35, 42, 49~5o, 61- 62, 66-68, 74-75, 82, 103- 105, 134, 160, 206, 212, 218, 257, 279, 293 Water, and plant growth, 269 as a drink, 7, 49, 224 carbonated, 88-89 "hard" water, 178-180 in the breath, 23 in relation to health, 53-57 peculiar behavior of, 141 properties of, 86-90 purification of, 53-57 sources of infection, 50, 53-54, 56 supply of, 53-57 uses of, 52-53, 56, 85 Water in the atmosphere, 93-94, 123-126 Weather, 133-140 and health, 113, 133-136 due to highs and lows, 137-140 forecasts of, 137-139 protection from, 133 Weight, 156 INDEX 383 Wells, 54 Winds, constant and variable, 128- Wheat, 325-328 130 food value of, 327-328 Wood pulp, 273-274 regions where grown, 325-328 Work, 160-163 Winds, 94, in, 113-114, 123-131, Y 137-139 Yellow fever, 39-40 UNIVERSITY OF CALIFORNIA LIBRARY This Jyfok isLDUE. on the last date, stamped belojg. TO32 1969 MAR 1 1969 RECEIVED '7 '69 -8 A LOAN DEPT LD 21-100l.12,'46(A2012si6)4120 .. YC 22703 387901 Q i 5? UNIVERSITY OF CALIFORNIA LIBRARY