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April 10, 2026
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"It was during the residence of our ingenious philosopher with his father in the country that he made himself master of Sir Isaac Newton's Principia, which he read in the English translation of Mr. Motte. It was here, likewise, he became acquainted with the science of fluxions; of which sublime invention he believed himself, for a while, to be the author, nor did he know for some years afterwards that a contest had been carried on between Sir Isaac Newton and Leibnitz for the honor of the great and useful discovery. What a mind was here! Without literary friends or society, and with but two or three books, he became, before he had reached his four and twentieth year, the rival of two of the greatest mathematicians in Europe."
"I do not design a machine which will give the ignorant in astronomy a just view of the solar system, but would rather astonish the skilful and curious observer by a most accurate correspondence between the situations and motions of our little representatives of our heavenly bodies and the situations and motions of those bodies themselves. I would have my orrery really useful by making it capable of informing us truly of the astronomical phenomena for any particular point of time, which I do not find that any orrery yet made can do."
"The direct tendency of (Astronomy) is to dilate the heart with universal benevolence, and to enlarge its views."
"Among the books he inherited from his uncle was an English translation of the "Principia" of Newton. Such was the progress which he made in mathematical knowledge, although now destitute of any aid, that he was enabled to accomplish the perusal of this work, for the proper understanding of which so much acquaintance with geometry and algebra is necessary, before he had attained his nineteenth year. Newton, as is well known, from deference to the practice of the ancient philosophers, adopts in this work the synthetic method of demonstration, and gives no clue to the analytic process by which the truth of his propositions was first discovered by him. Unlike the English followers of this distinguished philosopher, who contented themselves, for a time, with following implicitly in the path of geometric demonstration, which he had thus pointed out, Rittenhouse applied himself to search for an instrument, which might be applied to the purpose of similar discoveries, and in his researches attained the principles of the method of fluxions. So ignorant was he of the progress which this calculus had made, and of the discussions in relation to its invention and improvement, that he for a time considered it as a new discovery of his own. In this impression, however, he could not have long continued; as he made, in his nineteenth year, an acquaintance who was well qualified to set him right in this important point."
"See the sage Rittenhonse, with ardent eye, Lift the long tube and pierce the starry sky; Clear in his view the circling systems roll, And broader splendours gild the central pole. He marks what laws th' eccentric wand'rers bind, Copies Creation in his forming mind, And bids, beneath his hand, in semblance rise, With mimic orbs, the labours of the skies. There wond'ring crowds with raptur'd eye behold The spangled heav'ns their mystic maze unfold; While each glad sage his splendid hall shall grace, With all the spheres that cleave th' ethereal space."
"I have no health for a soldier, and as I have no expectation of serving my country in that way, I am spending my time in the old trifling manner, and am so taken with optics, that I do not know whether, if the enemy should invade this part of the country, as Archimedes was slain while making geometrical figures on the sand, so I should die making a telescope."
"The most noted mathematician and astronomer of early times [in the U.S.] was not a professor in a college, nor had he been trained within college walls. We have reference to David Rittonhouse."
"His invention, whatever it may have been, was not of sufficient importance to deserve the name of an "invention of fluxions." If Rittenhouse actually made an invention of such transcending magnitude before the age of twenty, and at a time when he had hardly begun his scientific studies, how is it that he made not the slightest approach to any similar discovery during the forty-four years of his maturer life? Though always a passionate lover of scientific pursuits, he made no original contributions whatever to the science of pure mathematics. Science is indebteded to him chiefly for his orreries and the observations of the transit of Venus. ...the alleged invention of fluxions was little more than a "rumor set afloat by idle gossip." It serves to show us, however, in what unbounded admiration he was held by his countrymen."
"As a mechanic, Rittenhouse became celebrated for the extreme exactness and finish of his workmanship. Especially celebrated were his chronometer clocks. It was while thus engaged in the manufacture of clocks that he planned and executed an instrument which brought into play both his mechanical and mathematical skill. ...the orrery. It was, indeed, intended to be a sort of a perpetual astronomical almanac, in which the results, instead of being exhibited in tables, were to be actually exhibited to the eye. His orrery greatly exceeded all others in precision. It attracted very general attention among well informed persons... There arose a lively competition between different colleges in this country for the possession of this orrery."
"Science is the future of mankind."
"Quantum physics is no longer an abstract theory for specialists. We must now absolutely include it in our education and also in our culture."
"The world, I think, will wait a long time for Nikola Tesla's equal in achievement and imagination."
"Men substitute words for reality and then argue about the words."
"I thought Armstrong would invent some kind of a filter to remove static from our AM radio. I didn't think he'd start a revolution—start up a whole damn new industry to compete with RCA."
"I was working with a Crookes tube covered by a shield of black cardboard. A piece of barium platino-cyanide paper lay on the bench there. I had been passing a current through the tube, and I noticed a peculiar black line across the paper. … The effect was one which could only be produced, in ordinary parlance, by the passage of light. No light could come from the tube, because the shield which covered it was impervious to any light known, even that of the electric arc. … I did not think; I investigated. I assumed that the effect must have come from the tube, since its character indicated that it could come from nowhere else. I tested it. In a few minutes there was no doubt about it. Rays were coming from the tube which had a luminescent effect upon the paper. I tried it successfully at greater and greater distances, even at two metres. It seemed at first a new kind of invisible light. It was clearly something new, something unrecorded."
"Shall an invention be patented or donated to the public freely? I have known some well-meaning scientific men … to look askance at the patenting of inventions, as if it were a rather selfish and ungracious act, essentially unworthy. The answer is very simple. Publish an invention freely, and it will almost surely die from lack of interest in its development. It will not be developed and the world will not be benefited. Patent it, and if valuable, it will be taken up and developed into a business."
"Röntgen was an experimental physicist of the old school and built most of his own equipment. ...It was Rontgen's custom, when beginning new investigations, to repeat important experiments made previously by others in the same field. Since he was repeating Hertz' and Lenard's experiments with cathode rays, he used an armamentarium employed by those workers... he extended his experiments to include a Hittorf-Crookes' tube... when he discovered the new rays. The whole room was darkened... Röntgen suddenly saw a few brightly fluorescent crystals which lay on the table at some distance from the tube."
"Röntgen has familiarized us with an order of vibrations of extreme minuteness compared with the smallest waves with which we have hitherto been acquainted, and of dimensions comparable with the distances between the centers of the atoms of which the material universe is built up; and there is no reason to suppose that we have here reached the limit of frequency."
"The lesson of the laboratory was eloquent. Compared, for instance, with the elaborate, expensive, and complete apparatus of, say, the University of London, or any of the great American Universities, it was bare and unassuming to a degree. It mutely said that in the great march of science it is the genius of the man, and not the perfection of the appliances, that breaks new territory in the great territory of the unknown. ...the discoverer himself had done so much with so little."
"Anyone who has had actual contact with the making of the inventions that built the radio art knows that these inventions have been the product of experiment and work based on physical reasoning, rather than on the mathematicians' calculations and formulae. Precisely the opposite impression is obtained from many of our present day text books and publications."
"Having discovered the existence of a new kind of rays, I of course began to investigate what they would do. … It soon appeared from tests that the rays had penetrative power to a degree hitherto unknown. They penetrated paper, wood, and cloth with ease; and the thickness of the substance made no perceptible difference, within reasonable limits. … The rays passed through all the metals tested, with a facility varying, roughly speaking, with the density of the metal. These phenomena I have discussed carefully in my report to the Würzburg society, and you will find all the technical results therein stated."
"I am not a prophet, and I am opposed to prophesying. I am pursuing my investigations, and as fast as my results are verified I shall make them public."
"We shall see what we shall see. We have the start now; the developments will follow in time."
"Röntgen retained the characteristic of a strikingly modest and reticent man. Throughout his life he retained his love of nature and outdoor occupations. Many vacations were spent at his summer home at Weilheim, at the foot of the Bavarian Alps, where he entertained his friends and went on many expeditions into the mountains. He was a great mountaineer and more than once got into dangerous situations. Amiable and courteous by nature, he was always understanding the views and difficulties of others. He was always shy of having an assistant, and preferred to work alone. Much of the apparatus he used was built by himself with great ingenuity and experimental skill."
"On July 20, 1969, when Neil Armstrong, another American born and raised in southwestern Ohio, stepped onto the moon, he carried with him, in tribute to the Wright brothers, a small swatch of the muslin from a wing of their 1903 Flyer."
"Twenty minutes later the third flight started. This one was steadier than the first one an hour before. I was proceeding along pretty well when a sudden gust from the right lifted the machine up twelve to fifteen feet and turned it up sidewise in an alarming manner. It began sliding off to the left. I warped the wings to try to recover the lateral balance and at the same time pointed the machine down to reach the ground as quickly as possible. The lateral control was more effective than I had imagined and before I reached the ground the right wing was lower than the left and struck first. The time of this flight was fifteen seconds and the distance over the ground a little over 200 feet."
"Wilbur started the fourth and last flight at just 12 o’clock. The first few hundred feet were up and down as before, but by the time three hundred feet had been covered, the machine was under much better control. The course for the next four or five hundred feet had but little undulation. However, when out about eight hundred feet the machine began pitching again, and, in one of its starts downward, struck the ground. The distance over the ground was measured and found to be 852 feet; the time of the flight 59 seconds. The frame supporting the front rudder was badly broken, but the main part of the machine was not injured at all. We estimated that the machine could be put in condition for flight again in a day or two. While we were standing about discussing this last flight, a sudden strong gust of wind struck the machine and began to turn it over. Everybody made a rush for it. Wilbur, who was at one end, seized it in front, Mr. Daniels and I, who were behind, tried to stop it by holding to the rear uprights. All our efforts were vain. The machine rolled over and over. Daniels, who had retained his grip, was carried along with it, and was thrown about head over heels inside of the machine. Fortunately he was not seriously injured, though badly bruised in falling about against the motor, chain guides, etc. The ribs in the surfaces of the machine were broken, the motor injured and the chain guides badly bent, so that all possibility of further flights with it for that year were at an end."
"It impressed me that Thomas Edison and the Wright brothers were so single-minded in figuring out how to make a light bulb or an airplane. They spent lots of time obsessively perfecting their inventions."
"For two reasons we decided to use two propellers. In the first place we could, by the use of two propellers, secure a reaction against a greater quantity of air, and at the same time use a larger pitch angle than was possible with one propeller; and in the second place by having the propellers turn in opposite directions, the gyroscopic action of one would neutralize that of the other. The method we adopted of driving the propellers in opposite directions by means of chains is now too well known to need description here. We decided to place the motor to one side of the man, so that in case of a plunge headfirst, the motor could not fall upon him. In our gliding experiments we had had a number of experiences in which we had landed upon one wing, but the crushing of the wing had absorbed the shock, so that we were not uneasy about the motor in case of a landing of that kind. To provide against the machine rolling over forward in landing, we designed skids like sled runners, extending out in front of the main surfaces."
"Wilbur, having used his turn in the unsuccessful attempt on the 14th, the right to the first trial now belonged to me. After running the motor a few minutes to heat it up, I released the wire that held the machine to the track, and the machine started forward into the wind. Wilbur ran at the side of the machine, holding the wing to balance it on the track. Unlike the start on the 14th, made in a calm, the machine, facing a 27-mile wind, started very slowly. Wilbur was able to stay with it till it lifted from the track after a forty-foot run. One of the life saving men snapped the camera for us, taking a picture just as the machine had reached the end of the track and had risen to a height of about two feet. The slow forward speed of the machine over the ground is clearly shown in the picture by Wilbur’s attitude. He stayed along beside the machine without any effort."
"We dared to hope we had invented something that would bring lasting peace to the earth. But we were wrong ... I don't have any regrets about my part in the invention of the airplane, though no one could deplore more than I do the destruction it has caused. I feel about the airplane much the same as I do in regard to fire. That is, I regret all the terrible damage caused by fire, but I think it is good for the human race that someone discovered how to start fires and that we have learned how to put fire to thousands of important uses."
"The course of the flight up and down was exceedingly erratic, partly due to the irregularity of the air, and partly to lack of experience in handling this machine. The control of the front rudder was difficult on account of its being balanced too near the center. This gave it a tendency to turn itself when started; so that it turned too far on one side and then too far on the other. As a result the machine would rise suddenly to about ten feet, and then as suddenly dart for the ground. A sudden dart when a little over a hundred feet from the end of the track, or a little over 120 feet from the point at which it rose into the air, ended the flight. As the velocity of the wind was over 35 feet per second and the speed of the machine against this wind ten feet per second, the speed of the machine relative to the air was over 45 feet per second, and the length of the flight was equivalent to a flight of 540 feet made in calm air. This flight lasted only 12 seconds, but it was nevertheless the first in the history of the world in which a machine carrying a man had raised itself by its own power into the air in full flight, had sailed forward without reduction of speed, and had finally landed at a point as high as that from which it started."
"At twenty minutes after eleven Wilbur started on the second flight. The course of this flight was much like that of the first, very much up and down. The speed over the ground was somewhat faster than that of the first flight, due to the lesser wind. The duration of the flight was less than a second longer than the first, but the distance covered was about seventy-five feet greater."
"Learning the secret of flight from a bird was a good deal like learning the secret of magic from a magician. After you once know the trick and know what to look for you see things that you did not notice when you did not know exactly what to look for."
"If we all worked on the assumption that what is accepted as true is really true, there would be little hope of advance."
"Heat rays have the same nature as light rays... The invisible heat rays are distinguished from light rays only by the period of or the wave length."
"All heat rays follow the same laws in their propagation, which are known for light rays."
"Look here, I have succeeded at last in fetching some gold from the sun."
"Of the heat rays... sent... to a body by its surroundings a part are absorbed, the others are... varied by reflection and . The rays refracted and reflected... pass off... with those sent out by it, without... mutual disturbance..."
"Through the radiations... a body sends out, the quantity of ... it contains will... sustain a loss... equivalent to the ' of those rays, and through the heat rays... it absorbs, a gain... equivalent to the vis viva of the absorbed rays."
"In 1854 he... became associated with Bunsen. ...[H]e ...for twenty years ...in connection with Bunsen achieved some of the most important discoveries in the history of physical science."
"In 1875 he accepted... the chair of at Berlin where he became associated with his former colleague von Helmholtz."
"By 1845 he had investigated electric currents, and established the two so-called Kirchhoff's laws for current conduction."
"His contributions extend over optics, heat, fluid, motion, electricity, elasticity, etc., and all bear the imprint of the great genius..."
"[M]ost radiations from gases are not exclusively thermal... [T]he substances, cited by Kirchhoff and Bunsen, also give off... chemical.., electrical and fluorescent radiations which Kirchhoff excluded in the proof of his law."
"[N]one of the gases giving line spectra at temperatures heretofore used, do so by simple , but essentially by luminescent actions (chemical, electrical, and photogenic), so... we cannot, in general, apply the law of Kirchhoff of the proportionality between radiation and absorption to either terrestrial or celestial substances. In these cases the principle of usually holds, since in luminescence the radiation of line spectra is accompanied by selective absorption of the same spectral lines, so that the law may be used qualitatively, which is... the way Kirchhoff and Bunsen... attempted to confirm it."
"His papers and lectures... form one of the enduring monuments in physical science."
"The formulation of the complete law for radiations of a is only given in part by Kirchhoff. The formula of Wien, and more particularly the most recent one of Planck, deduced on theoretical grounds, approximates closely the latest observations on a black body at different temperatures and over different wave lengths."
"The proof of this special law is similar to that of the general law, but simpler; it will therefore facilitate the understanding of the latter. Moreover, conclusions which are drawn from the special law will be used in the proof of the common law."
"Another result of this law... When a space is surrounded by bodies of the same temperature, and no rays can penetrate through these bodies, every pencil in the interior of the space is so constituted, with respect to its quality and intensity, as if it proceeded from a perfectly black body of the same temperature, and is therefore independent of the nature and form of the bodies, and only determined by the temperature. The truth... is evident if we consider that a pencil of rays, which has the same form, but the reverse direction to that chosen, is completely absorbed by the infinite number of reflections which it successively experiences at the assumed bodies. In the interior of an opaque glowing hollow body of given temperature there is, consequently, always the same brightness whatever its nature may be in other respects."