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according acting amplitude aperture apply axis bands beam becomes calculated called centre circle coincident colour combined complete condition consider constant construction crystal curves dark depends determined difference direction displacement distance disturbance drawn effect energy equal equation expression fact follows force given gives grating Hence homogeneous important incident inclination increased intensity interference intersection isochromatic light maximum means measured medium motion moving nearly normal observed obtain optic axes optical optical length original oscillations parallel particle passing path periodic phase plane plate polarized portion position principle prism propagation proportional quantities radius reflected refraction relation represents resultant right angles rings screen separate shown shows side simple slit space spectrum square straight successive sufficient surface theory thickness transmitted unit velocity vibration wave wave-front wave-length write zero zones
الصفحة 88 - ... might be constructed without an object-glass, if only there were no limit to the admissible focal length. This last proviso, however, as we shall see, takes away almost all practical importance from the proposition. "To get an idea of the magnitudes of the quantities involved, let us take the case of an aperture of 1/5 inch (inch = 2.
الصفحة 169 - If, however, this were not the case, we are so perfectly ignorant of the mode of action of the elements of the luminiferous ether on each other, that it would seem a safer method to take some general physical principle as the basis of our reasoning, rather than assume certain modes of action...
الصفحة 89 - Seen from a distance less than / it will appear magnified. Inasmuch as the arrangement affords a view of the sun with full definition and with an increased apparent magnitude, the name of a telescope can hardly be denied to it. "As the minimum focal length increases with the square of the aperture, a quite impracticable distance would be required to rival the resolving-power of a modern telescope. Even for an aperture of four inches /i would be five miles.
الصفحة 228 - No theory of evolution can be formed to account for the similarity of molecules, for evolution necessarily implies continuous change, and the molecule is incapable of growth or decay, of generation or destruction. None of the processes...
الصفحة 33 - ... nearly equal angles from the apertures at all distances, and wider also in the same proportion as the apertures are closer to each other. The middle ... is always light, and the bright stripes on each side are at such distances, that the light coming to them from one of the apertures must have passed through a longer space than that which comes from the other by an interval which is equal to the breadth of one, two, three or more of the supposed undulations...
الصفحة 33 - In order that the effects of two portions of light may be thus combined, it is necessary that they be derived from the same origin, and that they arrive at the same point by different paths, in directions not much deviating from each other.
الصفحة 169 - Light those formulas which represent the motions of a system of molecules acting on each other by mutually attractive and repulsive forces ; supposing always that in the mutual action of any two particles, the particles may be regarded as points animated by forces directed along the right line which joins- them. This last supposition, if applied to those compound particles, at least, which are separable by mechanical division, seems rather restrictive ; as many phenomena, those of crystallization...
الصفحة 88 - The image of the sun thrown on a screen at a distance exceeding 66 feet, through a hole ^ inch in diameter, is therefore at least as well defined as that seen direct. In practice it would be better defined, as the direct image is far from perfect. If the image on the screen be regarded from a distance /1( it will appear of its natural angular magnitude.
الصفحة 169 - of the advantages of this method, of great importance, is that we are " necessarily led by the mere process of the calculation, and with little care "on our part, to all the equations and conditions which are requisite and "sufficient for the complete solution of any problem to which it may be "applied.