Donor challenge: Your generous donation will be matched 2-to-1 right now. Your $5 becomes $15! Dear Internet Archive Supporter,. I ask only once a year. The Treatise on Light of Huygens has, however, withstood the test of time: and even now the exquisite skill with which he applied his. Treatise on Light In which are explained the causes of that which occurs in Christiaan Huygens. translated by Silvanus P. Thompson.
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Now passing to the investigation of the refractions which obliquely incident rays must undergo, according to our hypothesis of spheroidal waves, I saw that these refractions depended on the ratio between the velocity of movement of the light outside the crystal in the ether, and that within the crystal.
Treatise on Light by Christiaan Huygens
Christiaqn this suffices to show that the ray will continue along the curved line which intersects all the waves at right angles, as has been said. Now these rays, instead of being straight as they are in homogeneous media, ought to be curved in an atmosphere of unequal penetrability.
Whence one sees that the movement passes with an extreme velocity which is the greater, the greater the hardness of the substance of the spheres. From this it will be seen with what facility, following our new Theory, we find not only the Ellipses, Hyperbolas, and other curves which Mr. But the time along AK is longer than that huyygens AL: The other six are composed of two acute angles and one obtuse.
I recognize myself to be much indebted to those who were the first to begin to dissipate the strange obscurity in which these things were enveloped, and to give us hope that they might be explained by intelligible reasoning.
For this sphere being for example of silver, it is certain that it contains some of the ethereal matter which serves for light, since this was there as well as in the chrisiaan when the opening of the sphere was closed.
For the force of these waves must grow feeble in proportion as they move away from their origin, so that the action of each one in particular will christiwan doubt become incapable of making itself felt to our sight.
It is true that his wave theory was far from the complete doctrine as subsequently developed by Thomas Young and Augustin Fresnel, and belonged rather to geometrical than to physical Optics.
Treatise on Light
Bartholinus believed, since that inclination is only 70 degrees 57 minutes, as was stated above. A nice impression of the properties of light are narrated in this book. Supposing then these spheroidal waves besides the spherical ones, I began to examine whether they could serve to explain the phenomena of the irregular refraction, and how by these same phenomena I could determine the figure and position tretise the spheroids: And one may even show that these interstices occupy much more space than the coherent particles which constitute the chriistiaan.
Perhaps the circumstance is due to the mistaken zeal with which formerly everything that conflicted with the cherished ideas of Newton was denounced by his followers. As regards the hardness of this stone, and the property which it has of being easily split, it must be considered rather as a species of Talc than of Crystal. Let the line AC represent a portion of a ligyt of light, the centre of which is supposed huuygens distant that this portion may be considered as a straight line.
Treatise on Light – Wikipedia
It is true that there remains here some difficulty in those experiments in which christian interior reflexion occurs without the particles of air being able to contribute to it, as in vessels or tubes from which the air has been extracted. I considered first the effect of waves so formed, as respects the ray which falls perpendicularly on the flat surface of a transparent body in which they should spread in this manner.
But it might here be asked: And this accords perfectly with experiment. To explain then the reasons of these phenomena according to our principles, let AB be the straight line which represents a plane surface bounding the transparent substances which lie towards C and towards N. And this ethereal matter, as has been shown above, consists of particles which just touch one another. We know that by means of the air, which is an invisible and impalpable body, Sound spreads around the spot where it has been produced, by a movement which is passed huyyens successively from one part of the air to another; and that the spreading of this movement, taking place equally rapidly on all sides, ought to form spherical surfaces ever enlarging and which strike our ears.
In Iceland are found great lumps of this Crystal, some of which I have seen of 4 or 5 pounds.
If Huygens had no conception of transverse vibrations, of the principle of interference, or of the existence of the ordered sequence of waves in trains, he nevertheless attained to a remarkably clear understanding of the principles of wave-propagation; and his exposition of the subject marks an epoch in the treatment of Optical problems. It appears from the things explained above that the progression or propagation of a small part of a wave of light is properly what one calls a ray.
And it must be noted that it is special to the plane through GCF and to those which are parallel to it, that all incident rays which are in one of these planes continue to be in it after they have entered the Crystal and have become double; for it is quite otherwise for rays in all other planes which intersect the Crystal, as we shall huygenns afterwards. Lewis Kreger rated it liked it Aug 05, And suppose that a ray has come from A, by B, to C, having been hujgens at B according to the law demonstrated a little before; that is to say that, having drawn PBQ, which cuts the plane at right angles, let christiqan sine of the angle ABP have to the sine of the angle CBQ the same ratio as the velocity of light in the medium where A is to the velocity of light in chtistiaan medium where Llght is.
Then I shall explain the phenomena of those rays which are said to suffer refraction on passing through transparent bodies of different sorts; and in this part I shall also explain the effects of the refraction of the air by the different densities of the Atmosphere.
And it will be seen hereafter that this hypothesis serves excellently to explain the double refraction of certain transparent bodies. Dianna Caley rated it really liked it Aug 07, Furthermore these refractions are not altogether constant in rteatise weathers, particularly at small elevations of 2 or 3 degrees; which results from the different quantity ttreatise aqueous vapours rising above the Earth. The effect is that objects seen through it, especially such as are placed right against it, appear double; and treatis a ray of sunlight, falling on one of its surfaces, parts itself into two rays and traverses the Crystal thus.
Treatise on Light | work by Huygens |
But that which I employed only as a hypothesis, has recently received great seemingness as an established truth by the ingenious proof of Mr.
When the angle DAQ is still large enough to enable the ray DA to pass, it is evident that the light from the portion AC of the wave is collected in a minimum space when it reaches BN. Of the solid angles there are two opposite to one another, such as C and E, which are each composed of three equal obtuse plane angles. When you buy the General Books edition of this book you get free trial access to Million-Books. Eric Byrnes rated it really liked it Jun 04, Trivia About Treatise on Light.
Thanks for telling us about the problem. But in order to explain these phenomena more particularly, let there be, in the first place, a piece ABFE of the same Crystal, and let the obtuse angle ACB, one of the three which constitute the equilateral solid angle C, be divided into two equal parts by the straight line CG, and let it be conceived that the Crystal is intersected by a plane which passes through this line and through the side CF, which plane will necessarily be perpendicular to the surface AB; and its section in the Crystal will form a parallelogram GCFH.
Let there be such a ray RC falling upon the surface CK. I shall therefore essay in this book, to give, in accordance with the principles accepted in the Philosophy of the present day, some clearer and more probable reasons, firstly of these properties of light propagated rectilinearly; secondly of light which is reflected on meeting other bodies.
But, on the other hand I am astonished also that even here these have often been willing to offer, as assured and demonstrative, reasonings which were far from conclusive.
The mode of making these observations exactly is as follows. In it he speculated on the existence of extraterrestrial christiaann, on other planets, which he imagined was similar to that on Earth.
That is to say they yield a little in themselves at the place where they are struck, and immediately regain their former figure. Just a moment while we sign you in to your Goodreads account. I found also that when QRE made a straight line, that is, when the incident ray entered the Crystal without being refracted as I ascertained by the circumstance that then the point E viewed by the extraordinary refraction appeared in the line CD, as seen without refraction I found, I say, then that the angle QRG was 73 degrees 20 minutes, as has been already remarked; and so it is not the ray parallel to the edge of the Crystal, which crosses it in a straight line without being refracted, as Mr.
Thus this infinite number of waves which originate at the same instant from all points of a fixed star, big it may be as the Sun, make practically only one single wave which may well have force enough to produce an impression on our eyes.
The majority of those who have written touching the various parts of Optics have contented themselves with presuming these truths.