Man’s desire to conquer the air is older than recorded history. When a kite was flown for the first time the principle of aviation, or dynamic flight, was uncovered. For centuries man has sought the mechanical equivalents for the things that keep a kite flying steadily in the air,—the power that lies in the cord that keeps a kite headed into the wind; an equivalent for the wind’s own power; an equivalent for the tail which controls the kite’s lateral and longitudinal balance.

Each separate part of the modern flying machine, or aeroplane, was worked out long ago, with the exception of the gas engine light enough and reliable enough to be used for this work. The present generation knows dynamic flight as a commonplace thing, not because we are so much more clever than previous generations in designing flying machines, but because of the development of the modern gasoline or internal combustion engine.

Who Invented Flying?

No one invented flying, nor did any one man invent all the separate parts of the flying machine. They are the result of evolution,—of the combined work and thought of hundreds of men, many of whose names are unrecorded. To attempt to find the true beginning of the modern flying machine would be as difficult as attempting to discover who planted the seed of the tree from which one has gathered a rose. But the tree from which all the flying machines, or aeroplanes, of today have sprung undoubtedly is Dr. Samuel Pierpont Langley, third secretary of the Smithsonian Institution.

Some of the Men Who Helped.

Taking the most conspicuous names of scientists who worked out various details of the aeroplane during the past century we find that a century ago Sir George Cayley built a machine on lines very similar to those accepted today, and he went so far as to foretell the necessity of developing the internal combustion engine before dynamic flight could be a success. Mr. F. H. Wenham, in 1866, also built a flying machine along conventional lines and tried to fly it with a steam engine, which of course, proved too heavy.

M. A. Penaud, a Frenchman, in experimenting with models, seems to have been the first to discover the necessity of vertical and horizontal rudders in maintaining balance. Mr. Horatio Phillips, an Englishman, discovered, and patented, the use of curved instead of flat surfaces for the planes. Otto and Gustav Lilienthal are said to have been the first to attempt to balance aeroplanes by flexing or bending the wings. Various others, including Messrs. Richard Harte, Boulton, Mouillard, worked out ideas for balancing machines by the use of auxiliary planes which could be set at different angles with regard to the line of flight, thus forcing the machines to different positions by the force of the air rushing against them.

Dr. Langley, trained in scientific investigation, conducted an elaborate series of experiments covering many years and costing thousands of dollars to test and prove the value of the claims of the earlier investigators. Some things which he thought he was the first to discover,—such as the effect of the vertical and horizontal rudders,—he later found had already been proven by others. Independently he covered the entire field of experiment and after building hundreds of small models he succeeded, in 1896, in making a machine weighing several pounds equipped with a very light steam engine which flew safely as long as the fuel lasted. For his early experiments Dr. Langley was afforded financial assistance by Mr. William Thaw of Pittsburg. After the success of his small machines Dr. Langley was asked to undertake the construction of a large, man-carrying machine, and Congress voted him $50,000 to carry on the work. A large share of this was spent on the development of a very light gasoline engine. The machine finally was completed, but was twice broken through defective launching apparatus. Congress and Dr. Langley were so ridiculed by the public press that the machine was temporarily abandoned. Not, however, until after Dr. Langley had successfully flown a steam driven machine much larger than many of the racing aeroplanes of today.

But eight years after Dr. Langley’s death, which is said to have been due to the heart-breaking disappointment he suffered in trying to demonstrate the large machine, Glenn H. Curtiss, at the request of the Smithsonian Institution, rebuilt the old Langley machine and succeeded in making a flight with it at Hammondsport, N. Y., on May 28, 1914.

While longer flights probably will be made with this machine none will attain greater importance, because this first flight with it was sufficient to establish for all time the fact that Dr. Langley built the first man-carrying machine equipped with a gasoline engine and able to fly and raise itself with its own power. This was considerably more than was accomplished by other machines for some time after Dr. Langley’s death. The Langley machine not only lifted the weight it was designed to fly with, but also carried pontoon and other fittings, added by Mr. Curtiss to make flight from the water possible, which added 340 pounds to the original weight of the machine.

The connection between Dr. Langley’s work and present machines is now very easy to trace, though not obvious until 1911, when the Smithsonian Institution published memoirs written by Dr. Langley in 1897, and some memoirs of Mr. Octave Chanute, a French engineer who resided in Chicago, and who forms one of the main connecting links. The chain is practically completed by notes left by the late Lieut. Thomas Selfridge, U. S. A., America’s first martyr to aviation.

Dr. Langley’s knowledge is represented in modern aviation by three distinct lines. The central and most direct line is through Dr. Alexander Graham Bell, inventor of the telephone, to the Aerial Experiment Association, and thence to Mr. Glenn H. Curtiss, and finds its expression in what is known as the Curtiss type of machines.

Another line is that carried by a Mr. A. M. Herring to Mr. Chanute and by him transmitted to Mr. Wilbur Wright, finding expression in the Wright type of biplane.

The third line is that leading to the modern monoplane school; M. Bleriot having first copied in toto the tandem monoplane form, generally known as the Langley type, and later, with the development of better gasoline engines, developing into the monoplane as known today.

With the exception of M. Bleriot it is doubtful if the others fully realized the source of their inspiration,—not to call it information.

Dr. Bell was interested in Dr. Langley’s work for more than ten years before Dr. Langley gave up. He observed many of the trials, and his reports of the first successful flights are incorporated in the official publications of the Smithsonian Institution. Dr. Bell began some independent experiments, but following Dr. Langley’s death he formed the Aerial Experiment Association, to carry on the work left by Dr. Langley. The members of this organization were, Mr. Curtiss, at that time the most successful builder of light motors; Lieut. Thomas H. Selfridge, U. S. A.; Mr. J. A. D. McCurdy and Mr. F. W. Baldwin, two young Canadian engineers. Mrs. Bell financed the project, furnishing the sum of $35,000 for the experiments.

The Wright Brothers, for Wilbur Wright was joined by his brother Orville in the experiments, were the first to reap success from the seeds of Dr. Langley’s sowing. Mr. Chanute had been experimenting with a biplane form of motorless glider with little success, because of lack of means for balancing the machines in the air, until he was joined by a former employe of Dr. Langley. He appears to have imparted to Mr. Chanute the secret of the stabilizing effect of the Penaud tail, or combination of vertical and horizontal rudders. Thereafter hundreds of successful gliding flights were made with the Chanute biplane, though Chanute seems not to have grasped the full significance of the rudders,—though it was well understood by Dr. Langley. To the Chanute machine, as described to him, Mr. Wright added first the idea of flexing or warping the wings, after the fashion set by the Lilienthals. He found, however, as Dr. Langley had found years before, that in attempting to correct lateral balance in this way caused the aeroplane to swerve to such an extent that the fixed vertical rudder, as originally employed, did not correct the upsetting tendency that was developed. Mr. Wright then arranged his rudder in such a way that when the wing was warped the rudder turned in a way to offset the swerve. This combination was patented all over the world and has resulted in much complicated litigation.

To this machine the Wright Brothers added a gasoline motor in December, 1903, and with it made numerous flights during 1904-5. Their claims were not generally credited however until a later date for their experiments had been conducted with considerable secrecy, and during 1906, 1907 and until late in 1908 they did no more flying.

In the meantime M. Bleriot had made a copy of one of the early Langley tandem monoplane models and made some fairly successful flights with it in Europe. Later, as gasoline motors developed in power for weight, he reduced the rear surface until the modern monoplane evolved.

While Bleriot was working in Europe, Dr. Bell’s Aerial Experiment Association in America was evolving still another type of machine, and the members of the association made the first successful public flights in America. Mr. Curtiss won the Scientific American Trophy for the first time on July 4th, 1908, by a straightaway flight of more than a kilometer. The balancing system employed by the A. E. A. differed from that employed by the Wrights and by Bleriot in that small auxiliary planes took the place of warping planes for righting the machine. This they claimed to be a superior method, first, because it eliminated the use of the rudder as being absolutely essential to the balance of the machine; second, because it enabled them to make the main planes rigid throughout, and consequently stronger than the flexible planes.

There are several other names that must be mentioned in connection with the early history of successful flight; these are the Frenchmen, Messrs. Henri Farman, Maurice Farman, the brothers Voisin, and Santos Dumont. These produced some of the first notably successful aeroplanes in Europe but seem to have discovered nothing which has had any marked effect upon the later development of flying machines. M. Farman adopted the auxiliary planes used by the A. E. A. and modified them to suit his ideas.

Volumes could be, in fact, have been written about the exploits of the first demonstrators of the practical heavier-than-air flying machines,—of the crossing of the English Channel by Bleriot, of the flights by Wilbur Wright at Rheims, France; of Mr. Curtiss’ winning of the first Gordon Bennet International speed trophy and his flight down the Hudson from Albany to New York; of Orville Wright’s flight at Fort Meyer, and the death of Lieut. Selfridge who was flying with him. The barest record of these interesting accomplishments would fill volumes. Of the aeroplane proper it is enough to say here that since 1908 its development has been too rapid for accurate recording. In strength, in speed, in reliability, in size and carrying capacity, it has developed at a remarkable rate. At this writing the speed record is about 130 miles per hour; the duration record is more than 24 hours, non-stop; the distance record is some 1,300 miles in one day; the altitude record some 26,000 feet. New records succeed the old ones with such rapidity that probably before this can be printed all these present records will have been greatly eclipsed.

Meantime the aeroplane has developed greatly in other directions. In flying over land with the early types of machines many fatal accidents occurred, particularly to the fliers who gave exhibitions everywhere during 1909, 1910 and 1911. A majority of these accidents were indirectly due to the fact that a very smooth surface is required for landing a fragile machine running at high speed. The obvious expedient was to develop machines capable of rising from and alighting upon the water.

During the winter of 1910 and 1911 Mr. Curtiss, who had continued independent experiments upon the disbandment of the Aerial Experiment Association, succeeded in producing the first machine to safely leave and return to the water. For the development and demonstration of this type of flying machine he was awarded the Aero Club of America Trophy, and when during 1912 he produced still another type of water flying machine, the Curtiss Flying Boat, he was again awarded the Aero Club Trophy and also voted a Langley Medal by the directors of the Smithsonian Institution.

Not until the development of the flying boat did the general public begin to take a participative interest in aviation, but as soon as the comparative safety of this type of machine became apparent the new sport began to be taken up rapidly both in this country and in Europe. The experiences of naval fliers and amateurs alike went to show that water flying offered not only the fastest and most comfortable mode of rapid travel, but also the safest, for during 1913 several hundred thousand miles were flown by navy aviators and amateur enthusiasts in Curtiss water flying machines without a single serious accident.

What aviation will mean to future generations,—even to this generation in the course of a few years,—it would be foolhardy to try to guess. Mr. Rodman Wanamaker already has agreed to furnish the financial support for Mr. Curtiss’ attempt to build a machine to fly across the Atlantic Ocean, from America to Europe. If the venture is successful it is expected the crossing will be made in a fraction of the time taken by the fastest Transatlantic liners. The discovery of new metals and new manufacturing methods will certainly result in the development of light motors that may be relied upon to run for days without stopping, and automatically stable aeroplanes seem to be not far away. This will result in overland flight as safe and sure as we now enjoy over water.

At present the greatest value of the aeroplane seems to be for military reconnaissance and all the great powers are striving their utmost to secure supremacy in the air. France, Germany, Russia and England have to date spent millions in developing aeroplane fleets. Only the government of the United States has failed as yet to appreciate the military significance of the flying machine. If the relative aeronautical strength of the world’s nations were represented alphabetically the U. S. would naturally scarce have to change its initial, U being slightly in advance of Z which would stand for Zululand. But even with its modest equipment the navy fliers of the United States proved the great worth of the aeroplane and the flying boat, when during the recent trouble in Mexico the air scouts gathered in a few minutes information that could only have been secured by days of cavalry scouting before the advent of the flying machine. Indeed, the name of Lieut. P. N. L. Bellinger, the most able of the naval fliers at Vera Cruz, has figured more prominently in the despatches from the front than that of any other officer connected with the expedition.

Flying seems certain in the very near future to take its place as the fastest, safest and most comfortable mode of conveyance. The flying boat will render quickly accessible the vast country lying along the great rivers of South America, Africa, and Australia; it will bridge the great lakes and the oceans; bring near together the islands of the Pacific and Indian oceans. It will make imperative, because of the speed with which distances will be traversed, of a language common to all peoples; and treble man’s life without extending his years by making it possible to see and do three times as much in the same length of time.

Ten years ago on that day, December 17, 1913, Wilbur and Orville Wright made four flights on the coast of North Carolina near Roanoke Island, a spot historic in America’s history as the site of the first English settlement in the Western Hemisphere.

The first flight started from level ground against a 27-mile wind. After a run of 40 feet on a monorail track, the machine lifted and covered a distance of 120 feet over the ground in 12 seconds. It had a speed through the air of a little over 45 feet per second, and the flight, if made in calm air, would have covered a distance of over 540 feet.

Altogether four flights were made on the 17th. The first and third by Orville Wright, the second and fourth by Wilbur Wright. The last flight was the longest, covering a distance of 852 feet over the ground in 59 seconds. After the fourth flight, a gust of wind struck the machine standing on the ground and rolled it over, injuring it to an extent that made further flights with it impossible for that year.

The gliding experiments of Lilienthal in 1896 led the Wright Brothers to become interested in flight. The next four years were spent in reading and theorizing. In the Fall of 1900 practical experiments were begun with a man-carrying glider. These experiments were carried on from the sand hills near Kitty Hawk, North Carolina. The first glider was without a tail, the lateral equilibrium and the right and left steering were obtained by warping of the main surfaces. A flexible forward elevator was used. This machine was flown as a kite with and without operator, and several glides were made with it.

A second machine was designed of larger size, and many glides were made with it in 1901. This machine was similar to the one of 1900 but had slightly deeper curved surfaces. Experiments with this machine demonstrated the inaccuracy of all the recognized tables of air pressures, upon which its design had been based.

In 1902 a third glider was constructed, based upon tables of air pressures made by the Wright Brothers themselves. The lateral control was maintained by warping surfaces, and a vertical rear rudder operated in conjunction with the surfaces. Nearly a thousand gliding flights were made with this machine.

In 1903, the Wright Brothers designed a machine to be driven with a motor. They also designed and built their own motor. This had four horizontal cylinders, 4 in. by 4 in., and developed 12 h.p. Two propellers, turning in opposite directions, were driven by chains from the engine. After many delays the machine was finally ready and was flown on the 17th of December, 1903, as related above.

In the Spring of 1904, power flights were continued near Dayton with a machine similar to the one flown in 1903, but slightly heavier.

The first complete circle was accomplished on the 20th of September, 1904, in a flight covering a distance of about one mile. Altogether 105 flights were attempted during the year, the longest of which were two of five minutes each, covering a distance of about three miles. All of the flights were started from a monorail.

After September a derrick and a falling weight were used to assist in launching the machine.

It was not till 1908 that the Wright Brothers found purchasers for their invention. In that year they made a contract to furnish one machine to the Signal Corps of the United States Army and to sell the rights to their invention in France to a French company. In both cases they agreed to carry a passenger in addition to the operator, fuel sufficient for a flight of 100 miles, and to make a speed of 40 miles an hour.

After making some preliminary practice flights at their old experiment grounds near Kitty Hawk in May, 1908, Wilbur Wright went to France to give demonstrations before the French Syndicate and Orville Wright to Washington to deliver the machine to the United States Signal Corps. The machines used by Wilbur Wright had been standing in bond in the warehouse at Havre since August of the year before. Owing to damage done to the machine in shipment, it was not ready for the official demonstrations until late in the year.

Meanwhile Orville Wright in September, 1908, started demonstrations of the machine contracted for by the United States Government. On the 9th he made two flights, one of 57 minutes, and the other one hour and 2 minutes, world’s records. On the 10th and 11th, these records were increased and on the 12th a flight of 1 hour and 15 minutes was made. On the 17th, the tests were terminated by an accident in which Lieutenant Selfridge met his death and Mr. Wright was severely injured, so that he was not able to complete the tests until the following year.

Four days after the accident, on the 21st of September, Wilbur Wright made a flight of 1 hour and 31 minutes at Le Mans, France, which record he improved several times during the following months, and on the 31st of December, won the Michelin Trophy by a flight, in which he remained in the air 2 hours and 24 minutes.

Where Is the Wind When It Is Not Blowing?

The answer is, of course, that there isn’t any wind then. To understand this perfectly we must study a little and find out what wind is. In plain words it is nothing more than moving air.

If you make a hole in the bottom of a pail of water the water will run out slowly. If you knock the whole bottom out of the pail filled with water, the water will rush out before you know it.

That is about what happens to make the wind. The air is constantly full of air currents, like the currents you can see in a river. Down the middle of the river you may notice a softly-flowing current going straight. Along the shores there will be little side currents going in all directions, and you may find some little whirlpools. That is exactly what we should see in the air if we could see air currents.

Where Does the Wind Begin?

The movement of these currents of air leaves many pockets of space where there is no air, and when one of these is uncovered the air rushes in and creates a wind in doing so. These air currents are continually pressing against each other to get some place else. They change their direction according to the pressure that is being applied to them. Sometimes the pressure will be very light in one part of the air, many miles away perhaps, and then the air in another part, which is under great pressure, will rush with great force into the part where the pressure is light, and thus form a big wind. When the pressure stops the wind stops.

We have probably felt the wind which comes out of the valve of the automobile tire when the cap is taken off to pump up the tire. It is a real wind that comes out. The reason is that the air in the tube of the tire is under great pressure, and when the opportunity is given to get where the pressure is light it starts for that place with a rush and comes out of the valve a real wind.

What Causes the Wind’s Whistle?

The whistle of the wind is caused very much like the whistle you make with your mouth or the noise made by the steam escaping through the spout of the kettle. You do not hear the wind whistle when you are out in it. You can hear it when you are in the house and the wind is blowing hard. When the wind blows against the house it tries to get in through all the crevices, under the cracks of the doors, down the chimneys, wherever it finds an opening. And whenever it starts through an opening that is too small for it, it makes a noise like the steam coming out of the spout of the kettle, provided the opening is of a certain shape.

Not all the noises made by the wind, however, are made in this way. The wind in blowing against things makes them vibrate like the strings of a piano or violin, and when things vibrate, as we have already seen, they produce sound waves, which, when they strike our ears, produce sounds of various kinds. The wind even on ordinary days makes the telegraph and telephone wires hum, as you can prove to yourself by placing your ear against a telegraph or telephone pole, and whenever the wind makes anything vibrate, a great many queer sounds are produced, which often frighten us more than they should.

Why Does the Air Never Get Used Up?

Simply because it is constantly being replenished. The three gases, oxygen, nitrogen and carbonic acid gas, which are found in the air about us, are constantly being used up. All living animal creatures are at all times taking oxygen out of the air to live on. Certain microbes are using up quantities of the nitrogen all the time, and the plants live on the carbonic acid gas. But while these different kinds of life between them use up the air, they give back something also. The plants give off oxygen. The bodies of the animals and plants when they die decompose, and as they are full of nitrogen, that is given back to the air in that way, and then all living creatures are always throwing off carbonic acid gas through their lungs, and thus everything that is taken out of the air is put back again. The plants live on carbonic acid gas, and give us back oxygen. The living creatures live on oxygen and give off carbonic acid gas, and when they die their bodies put back in the air the nitrogen which the microbes take out, and so, consumption and production are about equal all the time.

Why Can’t We See Air?

We cannot see air because it has no color and is perfectly transparent. If at times it appears that there is color in the air it is not the air you see, but some little particles of various substances in it. Sometimes you think when you look off toward a range of mountains or hills, for instance, that the air is blue. You know the grass and trees on the mountains are green, so it cannot be they that have turned blue, and so you think the air is blue. But it is only the sunlight reflected to your eyes from the little particles of dirt and other substances which fill the air at all times which makes the blue that you see, and not the air.

Pure air is a mixture of gases without any color and is perfectly transparent. Air is nearly entirely composed of a gas called nitrogen—the remainder being oxygen with a little water and carbonic acid gas, which latter is thrown off in breathing. This is, however, but a very small percentage.

Air has been and still can be reduced to a liquid state, and with the use of it in this form many seemingly wonderful things can be done, which are interesting to look at, but have not as yet become commercially practical.

Why Does Thunder Always Come After the Lightning?

This occurs simply because lightning or light travels so much more quickly than sound. Light travels at the rate of 186,000 miles per second, and sound travels only at the rate of 1090 feet per second when the temperature is at 32 degrees. Now, the thunder and lightning come at the same time and place in the air, but the light travels so much faster that you see the lightning often quite some seconds before you hear the thunder. In fact, you can tell quite accurately how far away from you the flash of lightning and clap of thunder are by taking a watch and noting the number of seconds which elapse between the flash of the lightning and the time when you hear the roll of the thunder. If as much as five seconds elapse you can figure that it was about a mile away from you, since sound travels only about 1100 feet per second and there are 5280 feet in a mile. When the thunder and lightning come close together you may know that it is near by, and when they come at the same time you may be sure it is very close. When, therefore, you see the lightning and then have to wait several seconds for the noise of the thunder, you may rest easy about the lightning hurting you, because you know then it is too far away to harm you, and when it is so close that the lightning and thunder come simultaneously, there is no use being afraid, because if you were to be struck you would have been struck at the same instant or before you would have had time to notice that the lightning and thunder come together.

How Big Is the Sun?

It is very difficult to gain a clear idea of how very large the sun really is. We know from the scientists who have measured it with their accurate measuring instruments that it is 865,000 miles through it, and that at its largest part it is 2,722,000 miles around. Now, you can see why I said it is very difficult to get a clear conception of the sun’s size. A mile is quite a long distance to walk on a hot day. Now, the earth is 8000 miles through. If there were a tunnel right through the earth, like the subway, and you started to walk it, it would take you 83¹⁄₃ days if you walked day and night without stopping to rest or eat, if you kept going at the rate of four miles every hour. This would be a long, hot walk, for, of course, the inside of the earth is hot, as we have already learned. It would take an automobile, going at the rate of 40 miles an hour night and day, about nine days to make the trip through such a subway from one side of the earth to the other. That makes it look like a pretty big old earth, doesn’t it? But let us see what would happen if we started to do the same thing on the sun. The sun is 865,000 miles through. If you were to walk through a similar tunnel on the sun at four miles per hour it would take you 20 years, not counting the stops, and an automobile going 40 miles an hour day and night would take two years and a half to make the trip one way.

The sun is ninety million miles from the earth and an automobile travelling at the rate of forty miles per hour day and night on a straight road, without stopping, would be 257 years in getting there.

When we stop to think of how big the bulk of the sun is it is altogether beyond us. We have a general idea that our earth is a pretty large affair as worlds go, and yet we cannot conceive how much the bulk of the earth amounts to. Still, the sun is so large that it could contain a million worlds like our own.

How Hot Is the Sun?

We think the sun is pretty hot in summer when the thermometer goes up to 90 degrees in the shade or out. We begin to get sunburned long before it reaches that high. But right on the sun’s surface it is between 10,000 and 15,000 degrees hot. That is, of course, a degree of heat which we cannot conceive. How much hotter still it is on the inside of the sun we don’t as yet know. It must be awfully hot there.

Why Is It Warm in Summer?

It is warm in summer because at that season of the year the heat rays of the sun strike our part of the earth through less air. The blanket of air which surrounds the earth is very much in comparison as to thickness like the peeling of an orange and surrounds the earth in just the same way. If you stick a pin straight into an unpeeled orange you only have to stick it in a little way before you reach the juicy part of the orange, but if you stick the pin in at an angle the pin will travel a much longer ways through pure peeling before it strikes the juicy part. Now, then, in summer the rays of the sun come down to us straight through the peeling of air, and less of the heat is lost by contact with the air, and that makes it warmer in summer. The explanation also accounts for your next question.

Why Is It Cold in Winter?

In winter the heat rays of the sun strike at our part of the earth at the angle at which you stick the pin into the orange when you wish to make it travel through the most peeling. In winter the rays strike the earth at such an angle that a great deal of the heat is lost in travelling through the air, because they have to come through so much more of the air. Of course, the sun’s rays strike some part of the earth straight down through the peeling of air at all times, and at the equator this occurs all the year round, so it is always summer there, while at the North and South Poles the rays always strike the earth at the greatest possible angle, and it is always very cold winter there. In between, when it is neither hot nor cold, we have spring and fall, due to the fact that the rays come down at an angle, but not so great an angle.

Why Have We Five Fingers on Each Hand and Five Toes on Each Foot?

All animals, it seems, from a study of nature were started with ten fingers and ten toes, the fingers originally having been the toes of the fore legs. In a good many cases the environment in which animals have lived has caused a change in the formation of the ends of the limbs as well as in the limbs themselves. The horse, for instance, has developed into a one toe or one finger animal, while a cow is a two finger animal. The hen has only three toes on each foot and a part of another. But if we go back into the history and examine how the horses’ foot used to look we will find that he originally had five toes. The same is true of the cow and also the hen. Something happened to cause the change, for the rule of five fingers and five toes on the end of each limb has been universal. If you examine a chicken in a shell just before it is ready to come out, you can distinctly count five toes on each foot and at the ends of the wings you will see five little points, which under other conditions would develop into fingers, perhaps. Some of these toes of the new-born chicken do not develop. It can be accepted as a rule that creatures were intended in the original plan to have five fingers on each hand and five toes on each foot, making our count of tens, which is the world’s basis for counting, and has always been.

Why Do We Have Finger Nails?

Finger nails and toe nails are only another phase of the development of man from the animal that originally walked on four feet. Animals that walk on all fours use the finger and toe coverings which in man is the nail, to scratch in the ground, to attack enemies, and to climb with, and our nails of the present day are what the development of man into a civilized being has changed them to. At that, there are still uses for finger nails and toe nails, or man in his changing to a higher plane would have found a way to develop away from them. They are useful to-day in making our fingers and toes firm at the end, and enable us to pick up things more easily. The time may come when man will have neither finger nails nor toe nails.

Why Are Our Fingers of Different Lengths?

There is no known reason why our fingers should be of different lengths to-day; in fact, it is thought by some people that the hand would be stronger if the fingers were all of the same length. Certainly, however, the hands would not then be so beautiful, and it might not be so useful. The human hand to-day is perhaps the most versatile thing in the world. You can do more things with the hand than with any other thing in the world. The probability is that the shape of the hand to-day and the length of the fingers are the result of the different things the human being has called upon the hand to do during man’s development up to the present time.

We must go back to the time, however, when man walked on fours, for that is probably the real explanation. Originally man’s fingers were of different lengths because all four-footed animals had the same peculiarities. The shape and length of the toes and their arrangement were the ideal arrangement for giving the proper balance and support to the body, and in moving about and in climbing produced the best toe hold.

Why Does It Hurt When I Cut My Finger?

It hurts when you cut your finger, or, rather, where you cut it, because the place you have cut is exposed to the oxygen in the air, and as soon as it is so exposed a chemical action begins to take place, just as when you cut an apple and lay it aside you come back and find the cut surface all turned brown. If the apple could feel it would hurt also, because the chemical action is much the same. The apple has a skin which protects its inside from the oxygen in the air, and you have also a skin which protects you from the oxygen as long as it is unbroken.

What happens, of course, is this: When you cut your finger you sever the tiny little veins and nerves which are in your finger. They are spread all over your body like a net-work under the skin, close to the surface in most places. The nerves when cut send a quick message to the brain, with which they are connected, telling that they are damaged, and the brain calls on the heart and other functions to get busy and repair the damage along the line. There may be some hurt while this process of repairing is going on, but the principal part of your hurt, outside of what we call your feelings, is due to the fact that the inside of you is thus exposed to the chemical action of the air. Then I can hear you say next:

Why Don’t My Hair Hurt When It Is Being Cut?

It does not hurt to cut anything that has no nerves. There are no nerves in the hair which the barber cuts. If he pulls out a hair it hurts, because the root of the hair has nerves, which telegraph notice of the damage to the brain. When a dentist takes out or kills the nerve in your tooth you cannot have any more toothache in that tooth, because there is no nerve there to send the message to the brain. You can cut your finger nails without feeling pain, because they have no nerves at the ends, but underneath, where they join the skin of the finger, there are a great many nerves, and it hurts very much to bruise the nails at that location.

Of What Use Is My Hair?

Your hair is a relic of the days when the entire body was covered with hair, just like some animals to-day, to protect the body from the heat, cold and wet. Man has, however, for so long a time worn clothes over most of his body that the need of the hair to protect him from these elements has all but disappeared, and so also has the hair, excepting in such places as the top of the head and face and other exposed parts. If you were to go out into the woods without clothes and live a long time your body would probably again become covered with hairs. The time is coming, however, it is believed, when human beings will have no hair at all on their bodies. You have hair on your head, but if you were to wear a hat or cap all the time you would soon be bald. Hair is of no use to us to-day excepting to adorn our bodies and add to our appearance. This it seems to do to-day, probably because we are accustomed to seeing it, and will make no difference in our looks relatively if the time comes when we have no hair at all.

Why Does My Hair Stand On End When I Am Frightened?

It does this under certain conditions, because there is a little muscle down at the root of each hair that will make each hair stand up straight when this muscle pulls a certain way. It is difficult to say just how these muscles are caused to act in this way when we are frightened. We know that when thoroughly frightened our hair will sometimes stand straight up, and we know that it is this muscle at the root of each hair that makes it possible, but why it is that a big scare will make this muscle act this way we do not as yet know.

What Makes Some People Bald?

The chief cause of baldness is the lack of care of the hair. It is as necessary for the roots of the hair to have a free circulation of the blood and that the hair itself should have plenty of air as it is necessary for the brain to have a good circulation. A great many men become bald through wearing their hats most of the time. The hat pulled down tight over the head presses against the scalp and interferes with the circulation of the blood in the scalp. Then, also, many hats do not have any means of ventilation, and that keeps the pure air away from the hair. The hair then becomes sick and dies, just as flowers wilt if you keep them away from the air. You will notice that women do not become bald so easily. One reason is that even when the women wear large hats, as they often do, there is plenty of room for the air to circulate through the hair, even when the hat is on, and women’s hats are not pulled down tightly on the scalp. Therefore, they do not press on the arteries and veins in the scalp and interfere with the circulation of the blood. Another reason why women do not become bald is that the hair of women has long been their “crowning glory”; a man likes to see a fine head of hair on a woman, and as women have long tried to please men in every possible way, they take better care of their hair than men do, because they like to have the men consider it beautiful.

What Makes Some Things in the Same Room Colder than Others?

The objects in a room which has been kept at a given even temperature of heat will be all the same temperature, because heat spreads from one thing to another equally.

Still, if you put your hands on various objects in such a room some of them will feel colder than others. You touch the tiling of the fireplace and that will feel cool to you. On the other hand, the upholstered furniture will feel quite warm. The piano keys feel cool, while the wood of the piano and case is warm. The difference is due to the fact that heat or cold will run through some objects more quickly than through others. It will run through the tiling on the hearth and the piano keys more quickly than through the upholstering on the furniture or the wood of the piano case. When you touch a thing with your finger you supply some of the heat of your body to the object through your finger. If the object is the tiling on the hearth or the keys of the piano the heat runs through it quickly and you get a cold impression in your finger. On the other hand, if you touch the upholstery on the furniture, through which the heat runs slowly, you get a warm feeling for the very same reason. Thus, anything which carries the heat away from our contact quickly we call a cold feeling object, and if the object touched does not carry the heat away so quickly we call it a warm feeling object.

Why Does the Hair Grow After the Body Stops Growing?

The hair on our bodies is one of the things that is continually wearing or falling away, and since, like the skin, it is necessary to protect certain portions of the body, the hair keeps on growing long after the grown up period has arrived. The skin is a very necessary protection of the whole body, but is constantly being worn away, and is all the time being replaced. Your hair falls out when it is not healthy. Unless proper care is given to it, it will fall out and not grow in again, and then we become bald.

Will People All Be Bald Sometime?

There is a theory that before many years have passed human beings will lose all of the hairs which now grow on different parts of their bodies, due to the fact that we wear so much clothing and keep so much of our bodies away from the sunlight. If that time comes we shall have a hairless race of men and women.