BEFORE I describe the mechanical portion of my subject it may be useful if I make a few remarks on matters which, although personal to myself, have now become historical.
In October, 1859, I published in the Mechanic's Magazine a description of a cigar-shaped vessel to contain gas for support, and propellers placed in the same plane as the resistance, not yards below, as our French friends persist in placing the power. I subsequently concluded that the bird principle proffered greater chances of success.
Then on May 20, 1869, I described the flight of the albatross, which I now intend to treat upon. Bear in mind that this subject is more than 15 years old. The only result arising therefrom was a word or two at the meeting, in opposition, in the discussion that followed.
Well, in 1875 I built a flying machine for experiment. I made a steam engine which gave an actual 3 H.P., and which weighed altogether, engine and boiler combined, 80 lbs., and I applied its power in two separate experiments, the records of which will be found in the Reports of the Aeronautical Society, and also in the Encyclopaedia Britannica. These experiments cost me many hundreds of pounds, and one of the experiments was witnessed by the Duke of Argyll, the Duke of Sutherland, Lord Dufferin, and others; to whom I explained that a 30-H.P. engine would do 10 times the work of a 3-H.P. engine, but would not weigh more than five times 80 lbs. When this 3 H.P. engine lifted 120 lbs. before their eyes, I thought that the results warranted raising funds for further experiments, but I did not have the money myself, and I was unable to secure the assistance requisite to construct the larger machine.
On March 18, 1879, I constructed a model which, by its own power, traveled forward on the ground and rose a short distance from the ground. You will find this experiment recorded in the Report of the Aeronautical Society for that year, and I shall probably exhibit this model next year at one of the exhibitions.
I have sometimes been called sanguine, but I think this designation is a great mistake. I do not expect my countrymen to wake up to the importance of this subject during my lifetime. Fifteen years have passed since I gave the lesson of the albatross, and I expect it will take another 15 years before it is made use of.
Aerial navigation happens to be one of the subjects which I have studied, and it is a mistake to suppose that I am more anxious to effect that object than I am to effect improvements in marine propulsion and steam boilers and engines and other kindred subjects. Having quietly and patiently studied all these subjects, I now propose to give you a very simple and practical lesson on the flight of the albatross and its possible imitation by man.
You know, of course, that the albatross is the king of the sea, whose paradoxical soaring on motionless wings amazes travelers in southern seas. There are several varieties, but the great albatross is seldom found north of the 35th parallel of south latitude, and Mr. Wenham, in his celebrated paper on aerial locomotion, alluded to the bird as follows:
"One of the most perfect natural examples of easy and long sustained flight is the wandering albatross"--a bird for endurance of flight probably unrivalled. Found over all parts of the Southern Ocean, it seldom rests on the water. During storms, even the most terrific, it is seen now dashing through the whirling clouds, and now serenely floating, without the least observable motion of its outstretched pinions. "The wings of this bird extend 14 or 15 ft. from end to end, and measure only 8 1/2 in. across the broadest part. This conformation gives the bird such an extraordinary sustaining power, that it is said to sleep on the wing during stormy weather, when rest on the ocean is impossible. Rising high in the air, it skims slowly down, with absolutely motionless wings, till a near approach to the waves awakens it, when it rises again for another rest."
These are the observed facts, concerning which there is no dispute. The bird can remain indefinitely afloat upon the wind with no muscular exertion save the infinitesimal effort required for steering and balancing himself, and the question arises as to how he utilizes the wind.
Those who understand how to handle a sailing-vessel are aware that by "tacking" you can work a vessel to windward. The operation is effected by what is called "close hauling;" and any well-built fore-and-aft rigged vessel can sail within four points of the wind. If the line A B in diagram Fig. 84, indicates the direction of the wind, and the line C D the angle of the sail, then the line E F represents the actual force propelling the vessel forward. I presume that there is no one who will question the correctness of this. The wind may be blowing southeast, and the vessel can travel due east.
Now we come to the bird. I shall not go into the subject of the anatomy of the bird, or its food, etc., but would hope that there is no one here who holds that exploded theory that a bird fills its quills with a few cubic inches of gas and thereby becomes lighter than the air. Those bipeds, who shoot sea-gulls or other flying creatures, know full well that when the birds are maimed they fall with a thud; and under no circumstances can a bird materially diminish his own weight.
The albatross, when sailing over a very calm sea, is obliged to flap its wings in order to keep up its speed. But when a strong wind is blowing it obtains the very impulse that it needs without the necessity of using its wings as propellers; the waves are produced by the pressure of the wind upon the water and the weather face of the wave throws the wind upward, and gives the bird an upward thrust and impulse, of which it takes advantage, and thus saves itself the exertion of propulsion by flapping. The vertical direction of the wind above the wave-tops enables the bird to Ïclose haul" and thereby obtain gratuitous propulsion, which supplies his need until he reaches the next opportunity.
Now to prove the existence of this upward current. You have seen the spray thrown up from the tops of the waves, you have perhaps had a dash of it in your face while standing by the weather gunwale. A dash of spray over the bows of a cutter yacht has made you feel rather damp. These effects, and others I might name, all prove the existence of this impulse which serves the bird's wants, like the impulse imparted to a pendulum at the commencement of its oscillation.
Now if you look at my second diagram, Fig. 85, you will see what I mean. The line A B represents here the upward direction of the current, caused by the shape of the weather side of the wave and you will at once perceive the similarity of the forces, but you must bear in mind that one is horizontal and the other vertical.
It is quite immaterial which way the bird travels, except that its speed is much greater when it sails with the wind, or even "on a wind"--that is, with a beam wind. It can go dead to windward, but it can also go in any other direction, just as a vessel can, not only go to windward, but also with the wind free. There are, however, several advantages possessed by the bird over the ship which time will not permit of noticing.
You will therefore understand that the bird literally lies on the upward current: takes a propulsive thrust by depressing its head and sails to the next wave apex.
I must, however, warn you that this is only one kind of flight, and it is this one kind of flight which I shall now show you offers great facilities for man's imitation; and I now propose it as a first step toward conquering the air, not with cumbrous gas-bags and feeble screws rotated by leaky accumulators and a table-cloth for a rudder, but by following nature's perfect examples.
The method of flying which I have been attempting to describe to you is one which may be mastered by any intelligent man in a short time, and it is one which may be learned, in my judgment, with quite as much ease as bicycle riding.
His equipment will be a Boynton dress, a pair of stiff, immovable wings or aeroplanes, a light sea-anchor with a length of rope attached, and an accompanying boat. The frame of the planes will be extended behind so as to carry a horizontal rudder.
The Boynton dress and the aeroplanes will be firmly attached together. Each plane might be 18 ft. X 3 ft, and made stiff enough to bear three times the pressure that the total weight would impose upon them. If the total weight of man and equipment amounted to 250 lbs., I should test the strength of the planes by resting the center on its back and spreading upon the wings bags of sand to the amount of 750° lbs. If it sustained this weight fairly, then it would be safe for an experiment.
The albatross sometimes gets its initial velocity by starting from the apex of a wave while floating. In like manner the man could get his start by floating on the wave-top and using his sea-anchor, composed of several small hoops covered with canvas and open at one end. Holding on to the anchor and slacking out slowly, with his head to the wind, he would watch his opportunity, and pull the rope at the moment that he arrived at the top of a wave, when the wind would lift him just as a boy's kite is raised, and he could then go forward and pick up his anchor, emptying out the water as he did so. Every time he approached the apex of a wave (say from 10 to 20 ft. above it) he would depress the rudder, the effect of which would be to place his body momentarily in the position shown in diagram Fig. 85. This, with the impulse of the wind, would give him a high velocity which would not be very much lessened before he received another impulse.
Suppose a wind of 40 miles an hour were blowing, this line F would represent a propulsive force of about 50 lbs.; but the forward movement would probably reduce this to 30 lbs., and this would be an ample propelling force for the purpose.
If the initial velocity were obtained by the same means that birds obtain it, from a moderate elevation, it would be quite easy to skim over the water at 10 or 20 ft. above the waves.
The first experiment would, of course, be in company with a boat to render assistance in obtaining the first rise from the water, and in any other emergency. After a few experiments a mile or two would be easily covered, and after some practice the speed would far exceed that of the bird, because the weight is so much greater.
With a well-inflated Boynton dress and a good sea-boat in attendance there would be no danger to life.
If you ask of what use is this? I say business, pleasure, healthful exercise, and the accomplishment of the initial step toward actual flight.
If a man thus equipped can go in the teeth of a gale and carry a rope to a wreck that is business.
If a man thus equipped can travel at from 20 to 40 miles an hour over the waves, that is pleasure and healthful exercise.
But it will also teach him the enormous sustaining power to be derived from swift motion, and it will also explode many of the silly, unmechanical notions which are now held upon the subject.
We have had 100 years of balloons, and it is quite time that some advance should be made, leaving drifting bladders behind.
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