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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When you buy the General Books edition of this book you get free trial access to Million-Books. Let KF be the plane surface; A the point in the medium which the light traverses more easily, as the air; C the point in christiaa other which is more difficult to penetrate, as water.
Treatise on Light (Illustrated Edition)
Hugenius 14 April — 8 July was a prominent Dutch mathematician and scientist. I have then made no difficulty, in meditating on these things, in supposing that the emanation of light is accomplished with time, seeing that in this way all its phenomena lkght be explained, and that in following the contrary opinion everything is incomprehensible. And, first, it follows from what has been said on the production of Light, that each little region of a luminous body, such as the Sun, a candle, or a huygebs coal, generates its own waves of which that region is the centre.
For, the point H having been found and marked, as aforesaid, directly above the point E, I observed the appearance of the line CD, which is made by the extraordinary refraction; and having placed the eye at Q, so that this appearance made a straight line with the line KL viewed without refraction, I ascertained the triangles REH, RES, and consequently the angles RSH, RES, which the incident and the refracted ray make with the perpendicular.
For if what we have just said is true: I will finish this theory of refraction by demonstrating a remarkable proposition which depends on it; namely, that a ray of light in order to go from one point to another, when these points are in different media, is refracted in such wise at the plane surface which joins these two media that it employs the least possible time: For although it generates an infinitude of partial waves in the matter which is at the other side of AB, these waves never have a common tangent line either straight or curved at the same moment; and so there is no line terminating the propagation of the wave AC beyond the plane AB, nor any place where the movement is gathered together in sufficiently great quantity to produce light.
It was also in this book that Huygens published his method for estimating stellar distances. There is the further consideration in the emanation of these waves, that each particle of matter in which a wave spreads, ought not to communicate its motion only to the next particle which is in the straight line drawn from the luminous point, but that it also imparts some of it necessarily to all the others which touch it and which oppose themselves to its movement.
It is again a general law in all other transparent bodies that the ray which falls perpendicularly on their surface passes straight on without suffering refraction, and that an oblique ray is always refracted.
But it occurs also in other countries, for I have had some of the same sort which had been found in France near the town of Troyes in Champagne, and some others which came from the Island of Corsica, though both were less clear and only in little bits, scarcely capable of letting any effect of refraction be observed. All that I have just said has been likewise remarked by Mr.
It is not necessary to examine here the causes of this hardness, or of that springiness, the consideration of which would lead us too far from our subject.
Treatise on Light by Christiaan Huygens
And, since a ray perpendicular to a plane, and coming from a very distant source of light, is nothing else, according to the precedent Theory, than the incidence of a portion of the wave parallel to that plane, I supposed the straight line RC, huygenw and equal to AB, to be a portion of a wave of light, in which an infinitude of points such as RH ligyt C come to meet the surface AB at the points AK k B.
But here is another argument which proves this ready penetrability, not only in transparent bodies but also in all others. But this supposition ought not to seem to be an impossibility; since it is not a question of the transport of a body with so great a speed, but of a successive movement which is passed on from some bodies to others.
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The movement of Jupiter in his orbit while the Earth passed from B to C, or from D to E, is included in this calculation; and this makes it evident that one cannot attribute the retardation of these illuminations or the anticipation of the eclipses, either to any irregularity occurring in the movement of the little planet or to its eccentricity.
Descartes was impressed by his skills in geometry. It can do so because the spreading of the movement is successive. Then these lines HF, BG, will bear to one another the said ratio of the velocities. It must even occupy much less of it, since quicksilver is less heavy than gold, and the matter of gold is by no means dense, as follows from the fact that the matter of the vortices of the magnet and of that which is the cause of gravity pass very freely through it.
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. Luke Langley rated it liked it Dec 30, Text was easy to understand but the geometric proofs were less so. Now if about the centres A, B, one describes the circles DK, EL, which represent the spreading of the waves which originate from these two points, and if one draws the straight line KL which touches these two circles, it is easy to see that this same line will be the common tangent to all the other circles drawn about the centres F, H, etc.
Further, one cannot say that these bodies are of a texture similar to that of a sponge or of light bread, because the heat of the fire makes them flow and thereby treatlse the situation of the particles amongst themselves.
Now the portions H of this wave, during the time that O came to K, will have arrived at the surface CK along the straight lines H xand will moreover have produced in the crystal around the centres x some hemi-spheroidal partial waves similar to the hemi-spheroidal GSP gand similarly disposed, and of which libht major and minor diameters will bear the same proportions to the lines xv the continuations of the lines H x up to KB parallel to CO that the diameters of the spheroid GSP g bear to the line CB, or N.
Treatise on Light / Christiaan Huygens
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.
Christiaan Huygens – was a prominent physicist and astronomer. And it will be seen hereafter that this hypothesis serves excellently to explain the double refraction of certain transparent bodies. Now all these circumferences have for a common tangent the straight line BN; namely the same line which is drawn as a tangent from the point B to the circumference SNR which we considered first. For all these circles will be enclosed in onn another and will all pass beyond the point B.
Refresh and try again. This being so, it necessarily follows that every line intersecting one of these waves at right angles will pass above the point A, always excepting the one line which is perpendicular to the horizon. I took Litht for the exposed region of the surface. This may be proved by shutting up a sounding body in a glass vessel from which the air is withdrawn by the machine which Mr. But though we shall ignore the true cause of springiness we still see that there are many bodies which possess this property; and thus there is nothing strange in supposing that it exists also in little invisible bodies like the particles of the Ether.
Whence it is to be remarked that though the movement of the ethereal matter might communicate itself partly to that of the reflecting body, this could in chirstiaan alter the velocity of progression of the waves, on which the angle of reflexion depends.
Wikipedia — Treatise on Light. Rishikesh Pancholi rated it it was amazing Jan 12,