James Means

“ It is a competition between the two ends of the alley to see which end can make the most of what energy it has. Let the athlete exert all his strength to propel the spheres; see them arrive at the end of the alley after their journey of four hundred feet, with sluggish speed; the boy lifts them to a height of five feet to the chute, gives them a gentle push, and they are returned to the athlete’s end, arriving, not as sluggards, but as filled with energy. A short tack up and a long tack down is what does it. ”

“ This is the difference between a bird and a balloon.” (p. 130, Am. ed.)
“No bird is ever for an instant of time lighter than the air in which it flies; but being, on the contrary, always greatly heavier, it keeps possession of a force capable of supplying momentum, and therefore capable of overcoming any lesser force, such as the ordinary resistance of the atmosphere, and even heavy gales of wind. The force of gravitation, therefore, is used in [8] the flight of birds as one of the most essential of the forces which are available for the accomplishment of the end in view.” ”

“ In the first place, it is remarkable that the force which seems so adverse—the force of gravitation drawing down all bodies to the earth—is the very force which is the principal one concerned in flight, and without which flight would be impossible. It is curious how completely this has been forgotten in almost all human attempts to navigate the air. Birds are not lighter than the air, but immensely heavier. If they were lighter than the air they might float, but they could not fly. ”

“ In this description of the gull’s soaring to windward, the movement is reduced to its simplest elements, and it leaves out of account the graceful sinuosity of the bird’s airy travels, just as the teacher of dancing leaves grace out of account when she teaches the beginner the elements of the steps. ”

“ The heavier a bird is, the greater is its possible velocity of flight—because the greater is the store of force; or, to use the language of modern physics, the greater is the quantity of ‘potential energy’ which, with proper implements to act upon aerial resistance, it can always convert into upward, or horizontal, or downward motion, according to its own management and desires. ”

“ The answer is, encourage experiments with soaring machines. Have regattas and large prizes. Appeal to the people’s love of sport, and show what possibilities of recreation have been suggested by the experiments of Otto Lilienthal. Tobogganing on ice we can have only a few weeks in the year: tobogganing on air is possible at all seasons. When we have made our aeroplanes or aerocurves automatic in their steering action, flights like Lilienthal’s will be, to say the least, no more dangerous than football and quite as interesting. ”

“ While the bird’s momentum lasts it holds him firmly against the wind. At the point A the bird inclines his wings so that the wind strikes them on the under side, and he is lifted and lifted until, at the point B, his momentum is so reduced that he must tack; then he gives to the wind the thin edge of his wings and slides down to the point C, and then, with velocity regained, he repeats the manœuvre. Altitude sacrificed becomes velocity or momentum, and momentum sacrificed becomes altitude. ”

“ The fish needs a propeller, because it has no gravity in water; the bird does not need it, because it has gravity, and in that gravity has the best and smoothest of all conceivable means of propulsion, if he can make the wind lift him uphill whenever he has slid far enough downhill. If so, man commits an absurdity when he flies in the face of nature and assumes a propelling force where none is needed or exists.”
Later on in this article, I wish to describe an instrument, experiments with which can be made to answer for us the question as to whether or not a motor is needed ”

“ Under these circumstances a bird is sustained very much as a boy’s kite is sustained in the air. The string which the boy holds, and by which he pulls the kite downwards with a certain force, performs for the kite the same offices which its own weight and balance and momentum perform for the bird. The great long-winged oceanic birds often appear to float rather than to fly. The stronger is the gale, their flight, though less rapid, is all the more easy, so easy indeed as to appear buoyant ”

“ We will answer as well as we may the second question, Upon how gentle a decline may we hope to see an aerial machine maintain its initial velocity? When a railway car is at rest upon a smooth steel track having a down grade of one and twenty-three one-hundredths feet in every one hundred feet, it will remain at rest if undisturbed; but let it be once started downward by ever so slight an impulse and it will run down the track, gaining velocity to the end of the grade. ”

“ When a strong current of air strikes against the wings of a bird, the same sustaining effect is produced as when the wing strikes against the air. Consequently birds with very long wings have this great advantage, that, with pre-acquired momentum, they can often for a long time fly without flapping their wings at all. ”

“ The athlete represents the steam locomotive which, with all its polish and glitter, wastes energy. The boy represents the balloon, the lifter, which stores energy in matter by giving it altitude. The chute represents the free highway which through all the centuries men have supposed to be lacking. ”

“ As the century draws to its close the interest in the subject of aeronautics steadily increases. There already exists a keen curiosity to know what the aerial machine of the future is likely to resemble, and also to know whether the nineteenth or the twentieth century will claim it for its own. ”

“ Take, for example, one hundred pounds of lead and let energy be stored in it by giving it altitude, just as energy is stored in the weight of a clock when it is wound.
What is known as one-horse power is the amount of energy which must be exerted in lifting thirty-three thousand pounds at the rate of one foot per minute, or five hundred and fifty pounds at the rate of one foot per second, or fifty-five pounds at the rate of ten feet per second. ”

“ Very often the same effect is produced by allowing the force of gravity to act, and when the downward momentum has brought the bird close to the ground or to the sea, that force is again converted into an ascending impetus by a change in the angle at which the wing is exposed to the wind. ”

“ To give an illustration, it may be stated that if a man weighing one hundred and sixty-five pounds ascends a flight of steps ten feet high in three seconds, he exerts for the time being just one standard horsepower.
A small balloon which can lift one hundred pounds of lead three hundred and thirty feet high in one minute exerts one-horse power. ”

“ Imagine a bowling alley four hundred feet long, perfectly level, with an athlete at one end and a boy at the [20] other. Let the chute which returns the balls have a drop of fifteen inches in every one hundred feet; imagine the game to be one of rapid transit instead of ten-pins. ”

“ It depends upon the principle [18] that the pendulum rod always seeks the perpendicular; for instance, when the machine is launched pointing steeply downward, the positions of the pendulum and aeroplanes are as shown in Fig. 5; therefore the steering aeroplane C will, as soon as velocity is gained, lay a strong hold upon the wind of flight, and have a tendency to bring the machine into a horizontal course. ”

“ The indications seem to be that we must try to construct a machine analogous to the sailing-yacht rather than to the steamship, though perhaps the aerial machine of the future will be, so far as power is concerned, analogous to the yacht Sunbeam with its auxiliary screw. ”

“ All of the machines failed to gain sufficient velocity to clear the cliff.
Those who wish to experiment with machines weighing only a few pounds will probably find that a height of seventy or eighty feet will be sufficient if the position gives a straight drop. When it comes to experimenting with a soaring machine as large as Lilienthal’s and carrying a weight representing that of a man, the summit of Mt. Willard, near the Crawford House, N.H., will be found an excellent place.
[15]
A Soaring Machine. ”

“ Every student of the subject of flight should read the interesting work just mentioned. We may not agree with all the conclusions which are reached, yet the author gives most stimulating food for thought. ”

“ Just how much power can be thus utilized cannot well be told in advance of experiment; but we have calculated that under certain supposed conditions it may be as much as some six-horse power for an aeroplane with one thousand square feet of sustaining surface ”

“ The investigators of this subject are now divided into two camps: on the one side there are men who, like Mr. Maxim, are endeavoring to construct machines which will carry motors and therefore be self-propelling; on the other side there are men like Mr. ”