Part 29

Hail is the name given to the small masses of ice which fall in showers, and which are called hailstones. When a hailstone is examined it is found usually to consist of a central nucleus of compact snow, surrounded by successive layers of ice and snow. Hail falls chiefly in Spring and Summer, and often accompanies a thunderstorm. Hailstones are formed by the gradual rise and fall, through different degrees of temperature (by the action of windstorms), and they then take on a covering of ice or frozen snow, according as they are carried through a region of rain or snow.

With regard to rain, it may be said, in popular language, that under the influence of solar heat, water is constantly rising into the air by evaporation from the surface of the sea, lakes, rivers, and the moist surface of the ground. Of the vapors thus formed the greater part is returned to the earth as rain. The moisture, originally invisible, first makes its appearance as cloud, mist or fog; and under certain atmospheric conditions the condensation proceeds still further until the moisture falls to the earth as rain. Simply and briefly, then, rain is caused by the cooling of the air charged with moisture.

Why Does a Human Being Have To Learn to Swim?

It is strange, isn’t it, that almost every animal, excepting man and possibly the monkey, knows how to swim naturally; others such as birds, horses, dogs, cows, elephants, can swim as soon as they can move about alone.

The trouble with man in this connection is that his natural motion is climbing. He has been a climber ever since he was developed from the monkey, and when you throw him into the water before he has learned to swim, he naturally starts to climb and as a climbing motion won’t do, for swimming, the man will drown.

This climbing motion is as much of an instinct in man and monkeys as the instinct in dogs which causes him to turn round once or twice before he lies down just as his forefathers used to do ages ago when, as wild dogs, they first had to trample the grass before they could lie down comfortably.

Why Do I Get Cold in a Warm Room?

I suppose you mean the instances when you get cold while in a warm room even when you are perfectly well. This will happen often when all of the moisture in the room outside of what is in your body, is evaporated by the heat in the room. The remedy is, of course, to keep a pan of water some place in the room as the air has become too dry.

While heat is necessary to evaporate water, the process of evaporation produces cold. The quicker the evaporation the sharper the cold feeling produced. Now your body is continually evaporating the water from your body which comes out in the form of perspiration through the pores of the skin. This is one of nature’s ways of taking the impurities and waste out of the body. You know, of course, don’t you, that more than one-half the waste material which the body expels from the system comes out through the pores of the skin rather than through the canals.

When the air in the room becomes too dry, the evaporation on the outside of the body proceeds faster and makes you cold. By keeping water in some vessel in the room you keep the air of the room from becoming too dry.

Why Do They Call Them Wisdom Teeth?

The wisdom teeth are the two last molar teeth to grow. They come one on each side of the jaw and arrive somewhere between the ages of twenty and twenty-five years. The name is given them because it is supposed that when a person has developed physically and mentally to the point where he has secured these last two teeth he has also arrived at the age of discretion. It does not necessarily mean that one who has cut his wisdom teeth is wise, but that having lived long enough to grow these, which complete the full set of teeth, the person has passed sufficient actual years that, if he has done what he should to fit himself for life, he should have come by that time at the age of discretion or wisdom. As a matter of fact these teeth grow at about the same age in people whether they are wise or not.

What Makes Freckles Come?

Freckles are generally caused by the exposure of unprotected parts of the body to the sun, but this will not cause freckles on all people. Only people with certain kinds of sensitive skins freckle. What happens when freckles are produced in this way is this: The sunlight shining on the face, neck or arms of anyone who has a tendency to freckle, has a peculiar action on certain cells of the skin which produces a yellowish brown coloring pigment, which remains for a time.

Then again the skins of some people are so peculiarly sensitive the cells develop this kind of coloring matter in almost any kind of light and such people are, so to speak, apt to be freckled for life.

The Flying Boat

When Did Man First Try to Fly?

~HOW MAN LEARNED TO FLY~

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.

~EARLY TYPES OF FLYING MACHINES~

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.