Miracle at Kitty Hawk: Unpublished Letters of the Wright Brothers (Part I)

“It is possible to fly without motors, but not without knowledge and skill. This I conceive to be fortunate, for man, by reason of his greater intellect, can more reasonably hope to equal birds in knowledge than to equal nature in the perfection of her machinery.”

Bettmann / Getty

"One gets a certain thrill from discovering something others had not known," Orville Wright remarked to Fred C. Kelly, who was then working on a biography of the Wright brothers. After Orville's death, the family gave Mr. Kelly exclusive access to the Wright letters now in the Library of Congress. "I think," he writes us, "that they are the most important unpublished letters now available anywhere in the world. They deal with a subject that has brought a greater effect on the world than anything since the discovery of America." The Atlantic will serialize them in three installments, of which this is the first. Kelly is also the author of Miracle at Kitty Hawk: The Letters of Wilbur and Orville Wright.

Orville Wright often said that he and his brother Wilbur owed much to an upbringing that gave them "exceptional advantages." These were not from wealth. The family had to get along on the income of the father, Bishop Milton Wright, his salary from the United Brethren Church was never more than $900 a year. He sometimes got a little additional income from an Indiana farm, and he managed to pay for his daughter Katharine's education at Oberlin College, including two years in the preparatory department. But luxury money was scarce. Whatever Wilbur and Orville spent on hobbies they had to earn. The advantages Orville had in mind were "a home environment where the children were encouraged to pursue intellectual interests; to investigate whatever aroused curiosity."

It was a happy, congenial family. After the death of the mother, when Katharine, the youngest, was only fifteen years old and the two older brothers, Reuchlin and Lorin, had gone to homes of their own, those still under the parental roof were the more closely drawn together; what one was doing interested all. In the middle nineties, after Wilbur and Orville had started their bicycle business, Katherine was at Oberlin, and Bishop Wright made trips on church business. Thus the two brothers were frequently at home alone, and they were likely to continue working together when they came from their bicycle shop.

Orville was exactly three years older than his sister, each born on August 19; and Wilbur was four years older than Orville. Five feet ten and a quarter inches in height, Wilbur was taller than Orville by an inch and a half. Both were slender. Wilbur usually weighed about 140 pounds and Orville 5 pounds more. At the time he wrote the letter which follows, Wilbur looked perhaps a trifle older than his twenty-seven years, for his hair was thinning. Orville had not yet raised his mustache and looked boyish. For a time, after being hit in the face by a shinny club while skating, Wilbur had been in poor health, and did little but sit at home reading. The family sometimes wondered if he had become a bit lazy. Devoted as the brothers were, Orville would occasionally chide Wilbur for talking to him as if he were a "kid," and for saying or writing "I" when he meant "we."

September 1, 1894

The bicycle business is fair. Selling new wheels is about done for this year but the repairing business is good and we are getting about $20 a month from the rent of three wheels. We get $8 a month for one, 46.50 for another, and the third we rent by the hour or day. We have done so well renting them that we have held on to them instead disposing of them at once, although we really need the money invested in them. Could you let us have about $150 for a while? We think we could have it nearly all ready to pay back by the time you get home.

I have been thinking for some time of the advisability of my taking a college course. I have thought about it more or less for a number of years but my health has been such that I was afraid that it might be time and money wasted to do so, but I have felt so much better for a year or so that I have thought more seriously of it and have decided to see what you think of it and would advise.

I do not think I am specially fitted for success in any commercial pursuit even if I had the proper personal and business influences to assist me. I might make a living but I doubt whether I would ever do much more than this. Intellectual effort is a pleasure to me and I think I would be better fitted for reasonable success in some of the professions than in business.

I have always thought I would like to be a teacher. Although there is no hope of attaining such financial success as might be attained in some of the other professions or in commercial pursuits, yet it is an honorable pursuit, the pay is sufficient to enable one to live comfortably and happily, and [teaching] is less subject to uncertainties than almost any other occupation. It would be congenial to my tastes, and I think with proper training I could be reasonably successful.

Of course I could not attempt a college course unless you are able and willing to help me some. I think that by keeping a couple of bicycles to rent and by doing some repairing, and possibly a few sales, enough could be made to meet the greater part of the expense, or at least enough to help along quite a good bit. I think with six or eight hundred dollars I could complete the course, which would probably take about four years. I would be glad to have you think the matter over and give me your advice on it.
September 15, 1894

I received your letter. Yes, I will help you what I can in a collegiate course. I do not think a commercial life will suit you well. Probably you may not be able to go through college without some intermissions. I will loan you boys the $150 you ask.

Wilbur gave up the idea of going to college. Neither his nor Orville's formal education went beyond high school, and though each spent the time for a full course, neither ever received a di-ploma. The Wright family moved to Dayton Ohio, from Richmond, Indiana, just before the commencement exercises in Wilbur's final year and he did not bother to go back. Orville took special studies in his senior year in place of other work required for graduation.

In 1895 the Wright brothers read about the gliding experiments of Otto Lilienthal in Germany. (Lilienthal was far in advance of all others who ever worked on the flying problem before the Wrights.) They were fascinated by what little they could learn about Lilienthal, for it seemed to them that gliding through the air must be the king of sports. When they read in 1896 that Lilienthal had been killed in one of his experiments, they wondered if they could go on from where he and others had left off.

They read everything they could find about attempts to fly but the Dayton Public Library did not provide much, and in June, 1899, Wilbur wrote to the Smithsonian Institution in Washington for suggestions about reading matter. The Smithsonian sent them some pamphlets and a list of titles, including Octave Chanute's Progress in Flying Machines. Chanute, a successful construction engineer living in Chicago, had himself directed experiments with gliders of his own design, but these had not been highly successful. As a historian and bibliographer of man's attempts to fly, however, Chanute was the best. After reading Chanute's book, Wilbur Wright wrote to him, and this was the beginning of a correspondence which was to continue for ten years.

The intimate relationship between the Wrights and Chanute started by that first letter from Wilbur became of great importance to all three. Because Chanute early recognized that the Wrights were far ahead of their predecessors, he prodded them into continuing their experiments when they might have quit. His encouragement to the two brothers put them deeply in his debt. He in turn doubtless gained his greatest renown from being the confidant of the Wrights.

DAYTON, OHIO, May 13, 1900

For some years I have been afflicted with the belief that flight is possible to man. My disease has increased in severity and I feel that it will cost me an increased amount of money if not my life. I have been trying to arrange my affairs in such a way that I can devote my entire time for a few months to experiment in this field.

My general ideas of the subject are similar to those held by most practical experimenters, to wit: that what is chiefly needed is skill rather machinery. The flight of the buzzard and similar sailors is a convincing demonstration of the of skill and the partial needlessness of motors.

It is possible to fly without motors, but not without knowledge and skill. This I conceive to be fortunate, for man, by reason of his greater intellect, can more reasonably hope to equal birds in knowledge than to equal nature in the perfection of her machinery.

Assuming then that Lilienthal was correct in his ideas of the principles on which man should proceed, I conceive that his failure was due chiefly to the inadequacy of his method and of his apparatus. As to his method, the fact that in five years' time he spent only about five hours, altogether, in actual flight is sufficient to show that his method was inadequate. Even the simplest intellectual or acrobatic feats could never be learned with so short practice; and even Methuselah could never have become an expert stenographer with one hour per year for practice.

My observation of the flight of buzzards leads me to believe that they regain their lateral balance when partly overturned by a gust of wind, by a torsion of the tips of the wings. If the rear edge of the right wing tip is twisted upward and the left downward the bird becomes an animated windmill sand instantly begins to turn, a line from its head to its tail being the axis. It thus regains its level even if thrown on its beam's end, so to speak, as I have frequently seen them. I think the bird also in gen-eral retains its lateral equilibrium, partly by presenting its two wings at different angles to the wind, and partly by drawing in one wing, thus reducing its area. I incline to the belief that the first is the more important and usual method.

My business [the bicycle shop] requires that my experimental work be confined to the months be-tween September and January and I would be particularly thankful for advice as to a suitable locality where I could depend on winds of about 15 miles per hour without rain or too inclement weather. I am certain that such localities are rare.

I have your Progress in Flying Machines and your articles in the Annuals of '95, '96, and '97, as also your recent articles in the Independent. If can give me information as to where an account of Pilcher's experiments can be obtained I would greatly appreciate your kindness.

Chanute brought to the Wrights' attention other reading matter about their predecessors. Some of the impressions they got from their reading Wilbur described years later in a deposition before the United States Court of Appeals, in the patent infringement suit of The Wright Company vs. the Herring-Curtiss Co. and Glenn H. Curtiss.

Excerpt From the Testimony of Wilbur Wright
February 15, 1912

When we came to examine these books we were astonished to learn what an immense amount of time and money had been expended in futile at-tempts to solve the problem of human flight. Contrary to our previous impression, we found that men of the very highest standing in the professions of science and invention had attempted the problem. Among them were such men as Leonardo da Vinci, the greatest universal genius the world has ever known; Sir George Cayley, one of the first men to suggest the idea of the explosion motor; Professor Langley, secretary and head of the Smithsonian Institution; Dr. Bell, inventor of the telephone; Sir Hiram Maxim, inventor of the automatic gun; Mr. 0. Chanute, the past president of the American Society of Civil Engineers; Mr. Chas. Parsons, the inventor of the steam turbine; Mr. Thomas A. Edison, Herr Lilienthal, M. Ader, Mr. Phillips, and a host of others.

The period from 1889 to 1897 we found had been one of exceptional activity, during which Langley, Lilienthal, Chanute, Maxim, and Phillips had been feverishly at work, each hoping to win the honor of having solved the problem; but one by one they had been compelled to confess themselves beaten, and had discontinued their efforts. In studying their failures we found many points of interest to us.


The brothers soon assembled their first glider, at a cost of $15. It weighed about 52 pounds. Counting the "bows" at the ends of each wing surface, the span was nearly 17 feet, with a total lifting area of 165 square feet. A space 18 inches wide at the center of the lower surface, where the operator would lie "belly-buster," with feet over the rear spar, was left uncovered. The wing curvature was less than Lilienthal had used.

For their experiments the Wrights wanted a sandy area for soft landings, slopes free of trees or shrubs for gliding, and adequate winds. After writing to the Weather Bureau in Washington for information, they decided that Kitty Hawk, North Carolina, would meet their requirements better than any other place no farther from home.

September 3, 1900

I am intending to start in a few days for a trip to the coast of North Carolina in the vicinity of Roanoke Island, for the purpose of making some experiments with a flying machine. It is my belief that flight is possible and, while I am taking up the investigation for pleasure rather than profit, I think there is a slight possibility of achieving fame and fortune from it. It is almost the only great problem which has not been pursued by a multitude of investigators, and therefore carried to a point where further progress is very difficult. I am certain I can reach a point much in advance of any previous workers in this field even if complete success is not attained just at present. At any rate, I shall have an outing of several weeks and see a part of the world I have never before visited.
DAYTON, OHIO, September 5, 1900

We are in an uproar getting Will off. The trip will do him good. I don't think he will be reckless. If they can arrange it, Orville will go down as soon as Will gets the machine ready.
ELIZABETH CITY, N. C., September 9, 1900

I am at this place waiting for a boat to take me across Albemarle Sound to Kitty Hawk, North Carolina, which will be my address for the present. I supposed you knew that I was studying up the flying question with a view to making some practical experiments.

I chose Kitty Hawk because it seemed the place which most clearly met the required conditions. In order to obtain support from the air it is necessary, with wings of reasonable size, to move through it at the rate of 15 or 2O miles per hour. If there is no wind movement, your speed with reference to the ground must be the same. If the wind blows with proper speed, support can be obtained without movement with reference to the ground. It is safer to practice in a wind, provided this is not broken up into eddies and sudden gusts by hills, trees, and so forth.

At Kitty Hawk, which is on the narrow bar separating the Sound from the Ocean, there are neither hills nor trees, so it offers a safe place for practice. Also the wind there is stronger than any place near home and is almost constant, so that it is not necessary to wait days or weeks for a suitable breeze. It is much cheaper to go to a distant point where practice may be constant than to choose a nearer spot where three days out of four might be wasted.

I have no intention of risking injury to any great extent, and have no expectation of being hurt. I will be careful, and will not attempt new experiment in dangerous situations. I think the danger much less than in most athletic games.
KITTY HAWK, September 3, 1900

I have my machine nearly finished. It is not to have a motor and is not expected to fly in any true sense of the word. My idea is merely to experiment and practice with a view to solving the problem of equilibrium. I have plans which I hope to find much in advance of the methods tried by previous experimenters. When once a machine is under proper control under all conditions, the motor problem will be quickly solved. A failure of motor will then simply mean a slow descent and safe landing instead of a disastrous fall.

In my experiments I do not expect to rise many feet from the ground, and in case I am upset there is nothing but soft sand to strike on. I do not intend to take dangerous chances, both because I have no wish to get hurt and because a fall would stop my experimenting, which I would not like at all. The man who wishes to keep at the problem long enough to really learn anything positively cannot take dangerous risks. Carelessness and overconfidence are usually more dangerous than deliberately accepted risks. I am constructing my machine to sustain about five times my weight and am testing every piece. I think there is no possible chance of its breaking while in the air. If it is broken it will be by awkward landing.

My machine will be trussed like a bridge and will be much stronger than that of Lilienthal, which, by the way, was upset through the failure of a movable tail and not by breakage of the machine. The tail of my machine is fixed, and even if my steering arrangement should fail, it would still leave me with the same control that Lilienthal had at best. My machine is more simple in construction and at the same time capable of greater adjustment and control than previous machines.

I have not taken up the problem with the expectation of financial profit. Neither do I have any strong expectation of achieving the solution at the present time or possibly any time. My trip would be no great disappointment if I accomplished practically nothing. I look upon it as a pleasure at the same cost. I am watching my health very closely and expect to return home heavier and stronger than I left. I am taking every precaution about my drinking water.

On his way to Kitty Hawk, Orville took time to act on a financial problem.

ELIZABETH CITY, September 6, 1900

Tell Harry [an employee at the bicycle shop] to sell those rolls of tire tape in the box back of what he has been selling at 5 cents a roll. They were 10-cent rolls, but we must get rid of them. They are in tin-foil wrappers.
KITTY HAWK, October 14, 1900

We have been having a fine time. Altogether we have had the machine out three different days, of from two to four hours each time. Monday night and all day Tuesday we had a terrific wind, blowing 36 miles an hour. Wednesday morning the Kitty Hawkers were out early peering around the edge of the woods and out of their upstairs windows to see whether our camp was still in existence. We were all right, however, and though wind continued up to 30 miles, got the machine out to give it another trial. The wind was too strong and unsteady for us to attempt an ascent in it, so we just flew it like a kite, running down a number of strings to the ground, with which to work the steering apparatus. The machine seemed a rather docile thing, and we taught it to behave fairly well. Chains were hung on it to give it work to do, while we took measurements of the "drift" in pounds.

In the afternoon we took the machine to the hill just south of our camp, formerly known as "Look Out Hill," but now as the "Hill of the Wreck."

Well, after erecting a derrick from which to swing our rope with which we fly the machine, we sent it up about 920 feet, at which height we attempt to keep it by the manipulation of the strings to the rudder. The greatest difficulty is in keeping it down. It naturally wants to go higher and higher. When it begins to get too high we give it a pretty strong pull on the ducking string, to which it responds by making a terrific dart for the ground. If nothing is broken we start it up again. This is all practice in the control of the machine. When it comes down we just lay it flat on the ground and the pressure of the wind on the upper surface holds it down so tightly that you can hardly raise it again.

After an hour or so of practice in steering, we laid it down on the ground to change some of the adjustments of the ropes, when, without a sixteenth of a second's notice, the wind caught under one corner and, quicker than thought, it landed 920 feet away, a complete wreck. When it started I was standing at a rear corner holding one of the uprights. It just took me off my feet and landed me in the heap 929 feet away.

We had had a number of interesting experiences with it before, performing some feats which would almost seem an impossibility. We dragged the pieces back to camp and began to consider getting home. The next morning we had cheered up some and began to think there was some hope of repairing it.

The next three days were spent in repairing, holding the tent down, and hunting; mostly the last, in which occupation we have succeeded in killing two large fish hawks each measuring over 5 feet from tip to tip; in chasing a lot of chicken hawks till we were pretty well winded; and in scaring several large bald eagles.

This is a great country for fishing and hunting. The fish are so thick you see dozens of them when-ever you look down into the water. The woods are filled with wild game, they say; even a few "b'ars" are prowling about the woods not far away.

But the sand! The sand is the greatest thing in Kitty Hawk, and soon will be the only thing. The site of our tent was formerly a fertile valley, cultivated by some ancient Kitty Hawker. Now only a few rotten limbs, the topmost branches of trees that then grew in this valley, protrude from the sand. The sea has washed and the wind blown millions and millions of tons of sand up in heaps along the coast, completely covering houses and forest. Mr. Tate is now tearing down the nearest house to our camp to save it from the sand...

You can't get dirty. Not enough to raise the least bit of color could be collected under a finger nail. We have a method of cleaning dishes that has made the dish rag and the tea towel a thing of the past.

We need no introduction in Kitty Hawk. Every place we go we are called Mr. Wright. Our fame has spread far and wide up and down the beach.
KITTY HAWK, October 18, 1900

We spent half the morning yesterday in getting the machine out of the sand. When we finally did get it free, we took it up the hill, and made a number of experiments in a 925-mile wind. We have not been on the thing since the first time we had it out, but merely experiment with the machine alone, sometimes loaded with 75 pounds of chains. We tried it with tail in front, behind, and every other way. When we got through, Will was so mixed up he couldn't even theorize. It has been with considerable effort that I have succeeded in keeping him in the flying business at all. He likes to chase buzzards, thinking they are eagles, and chicken hawks, much better.
November 16, 1900

My brother and myself spent a vacation of several weeks at Kitty Hawk, North Carolina, experimenting with a soaring machine...

The machine had neither horizontal nor vertical tail. Longitudinal balancing and steering were effected by means of a horizontal rudder projecting in front of the planes. Lateral balancing and right and left steering were obtained by increasing the inclination of the wings at one end and decreasing their inclination at the other. The short time at our disposal for practice prevented as thorough tests of these features as we desired, but the results obtained were very favorable and experiments will be continued along the same line next year.


During the winter of 1900-1901 the Wrights went ahead with plans, determined before they had left Kitty Hawk, that their next experiments would be with a larger glider—large enough to be flown as a kite, with an operator aboard, in the kind of winds they could usually expect. The 1901 glider was of the same general design as the first one, but with considerably more area, for greater lifting power. They increased the curvature of the wings to conform to the shape on which Lilienthal had based his tables of air pressures. The front and rear edges of the wings were about 7 feet apart and the total span 22 feet. With the rear corners of the wings rounded off, and a section 20 inches wide removed from the middle of the lower wing, the lifting area was 290 square feet. The machine weighed 98 pounds, nearly double the earlier one. This was a much larger machine than anyone had ever dared try to fly. Although several glides on the day of the machine's first trial exceeded in distance the best of the year before, it was soon evident that in a number of respects the machine was not as good as the first one. With the wing camber recommended by Lilienthal, it could not glide at a slope as near to level as the 1900 machine had done.

When their friend Chanute had learned, during a visit to Dayton in June, that no doctor was available near their camp, he thought the brothers were taking big risks. He said he knew a young man in Coatesville, Pennsylvania, George A. Spratt, who had been making studies in aeronautics and who had had medical training. If the Wrights would board him at camp, Chanute said, he would pay Spratt's traveling expenses to Kitty Hawk and would feel compensated by the pleasure given, for Spratt had never seen gliding experiments. Chanute also asked if they would be willing to have with them E. C. Huffaker, a technical man, of Chuckey, Tennessee, who was building a glider for Chanute that he wanted to have tested. The Wrights consented. For a time, too, Chanute himself, on their invitation, was with them.

July 30, 1901

The most discouraging features of our experiments so far are these: The lift is not much over one third that indicated by the Lilienthal tables. As we had expected to devote a major portion of our time to experimenting in an 18-mile wind without much motion of the machine, we find that our hopes of obtaining actual practice in the air are decreased to about one fifth what we hoped, as now it is necessary to glide in order to get a sustaining speed. Five minutes' practice in free flight is a good day's record. We have not yet reached so good an average as this even.

The good points as indicated by the experiments already made are these: —

1. The machine is strong. It has suffered no injury although very severely used in some forty landings.

2. With less than an hour's practice we succeeded in getting a free flight of over 800 feet at an angle of 1 in 6. Many of our failures in other attempts were due only to the fact that the hill was not steep enough to really get a fair start. The machine starting so close to the ground that the least undulation caused the rear ends of the rib to touch the ground and thus prevent the machine turning up to sufficient angle to rise again.

3. We have experimented safely with a machine of over 300 square feet surface in winds as high as 18 miles per hour. Previous experimenters had pronounced a machine of such size impracticable to construct and impossible to manage. It is true that we have found this machine less manageable than our smaller machine of last year, but we are not sure that the increased size is responsible for it. The trouble seems rather in the travel of the center of pressure.

4. The lateral balance of the machine seems all that could be desired.

Wilbur Wright said, on their way home after the 1901 gliding experiments, that he didn't think man would fly in a thousand years. In a way, though, as Orville Wright said long afterward, it was encouraging to learn that the work of predecessors could not be relied upon. It meant that more knowledge was needed, rather than that flight was impossible.

CHICAGO, ILL., August 23, 1901

I have your welcome letter of the 22nd and am glad to know that you got through your experiments without accident. I think you have performed quite an achievement in sailing with surfaces wider than any which I dared to use, and on which a change of incidence by a wind gust would make so great a difference in the center of pressure.
DAYTON, OHIO, September 1, 1901

Well, after you left camp, conditions which you know were none too pleasant in some respects became even worse, as they were no longer relieved by your funny stories and pleasant company, so four days after you left we also broke camp and returned home...

I enclose a few prints. That of the Huffaker machine you will please not show too promiscuously. I took it as a joke on Huffaker but afterward it struck me that the joke was rather on Mr. Chanute, as the whole loss was his. If you ever feel that you have not got much to show for your work and money expended, get out this picture and you will feel encouraged.

We have been quite busy since returning home, putting in some new machinery and finishing a new gas engine on which we have been working for some time.

By Mr. Chanute's invitation I was up to Chicago a few days ago to address the Western Society of Engineers on our experiments. His faith in Lilienthal's tables is beginning to waver, though it dies hard.
DAYTON, OHIO, October 6, 1901

We have made the experiment of balancing a curved surface against a plane surface 66 per cent as large, placed normal to the wind, and find that instead of 5°, as called for in Lilienthal's table, an angle of 18° was required. The test was made by mounting the surfaces on a bicycle wheel turned over so that its axis was vertical.

We found it impossible to get satisfactory results with a natural wind, so we mounted the wheel on a spar projecting in front of a bicycle and made tests in an almost perfect calm. We rode at right angles to the wind so that the natural wind was first on one side and then on the other as the direction of the course was reversed.

That experiment with the bicycle was tried only once. They made their first wind tunnel of an old starch box. Then they rigged up a much better wind tunnel, about 6 feet long and 16 inches square (interior measurement), and for two months, toward the end of 1901, tested-more than two hundred types of wing surfaces. Among other things, they proved the fallacy of the sharp edge at the front of an airplane wing and the inefficiency of deeply cambered wings, which were then generally advocated by others. The immediate purpose of the experiments was to make sure, before Wilbur's Chicago speech was published, that he had not overstated in saying that all the published works relating to air pressures on curved surfaces were wrong. As the experiments continued, they marked a turning point in the efforts of man to fly, for they gave knowledge no one had ever had before, of how to design wings efficient enough to make possible a fIying machine. It is the design of the wings rather than the engine or propellers that enables a plane to lift itself in the air. If this were not so, a glider with neither an engine nor propellers could not fly.

DAYTON, OHIO, October 24, 1901

Since returning we have been experimenting some what with an apparatus for measuring the pressure of air on variously curved surfaces at different angles, and have decided to prepare a table which we are certain will be much more accurate than that of Lilienthal. Mr. Chanute has several times kindly offered to help bear the expense of these experiments but we have refused to accept money because we would be led to neglect our regular business too much if the expense of these experiments did not exercise a salutary effect on the time devoted to them.
DAYTON, OHIO, November 22, 1901

After almost numberless small changes we think our machine will now give results within 2 or 3 per cent of the real truth, and will give the same result at every test at any given angle. We are now engaged in making a large number of models of typical shapes and will measure them with the greatest care. The comparative lifts of different surfaces will be obtained with almost absolute correctness.
DAYTON, OHIO, December 15, 1901

We were pleased to receive your letter and the photograph of your new testing machine. It seems quite ingeniously designed and I think should give good results. As you say, the greatest trouble will probably be with the changeableness of the wind. If I understand you properly, the machine is intended for locating the center of pressure at any angle (or rather locating the angle for any center of pressure) and for finding the direction of the resultant pressure as measured in degrees from the wind direction.

I think I told you in my last that we had been experimenting with a "lift" measuring machine. We have carried our experiments further and have made a measurement of the lifts of about thirty surfaces. The results have rather surprised us as we find at angles of 7° to 15° with some surfaces a greater lift than Lilienthal gives in his table.
DAYTON, OHIO, December 15, 1901

I regret that we did not have time to carry some of these experiments further, but having set a time for the experiments to cease, we stopped when the time was up. At least two thirds of my time in the past six months has been devoted to aeronautical matters. Unless I decide to devote myself to something other than a business career, I must give closer attention to my regular work for a while. I hope at some later time to resume these investigations.
CHICAGO, ILL., December 19, 1901

I have read your letter . . . with absorbing interest. If your method and machine are reliable you have done a great work, and have advanced knowledge greatly. Your charts carry conviction to my mind and your descriptions and comments are very clear. I must especially commend the system by which you went about to ascertain the best form of surface, instead of trying haphazard experiments.

I very much regret, in the interest of Science, that you have reached a stopping place, for further experimenting on your part promises important results, yet my judgment cannot but approve of your decision, for I see as yet no money return for the pursuit, save from possible exhibition. If, however, some rich man should give you $10,000 a year to go on, to connect his name with progress, would you do so? I happen to know Carnegie; would you like for me to write to him?
Part 1 || Part 2 || Part 3

These letters and more are available in Fred C. Kelly's book, Miracle at Kitty Hawk: The Letters of Wilbur and Orville Wright.