Elements of Physics: Or, Natural Philosophy, General and Medical ; Explained Independently of Technical Mathematics, Том 1Underwood, 1829 |
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Elements of Physics: Or, Natural Philosophy, General and Medical ..., Том 1 Neil Arnott Полный просмотр - 1827 |
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aeriform animal appear atmosphere beautiful becomes bending body boiling bulb bulk burning called camera obscura carbon carbonic acid centre charcoal coal cold colours combustion common concave concave lens condensed convex convex lens cooled cosmorama cylinder degree dilatation direction distance earth equal expansion explained fact Fahrenheit fall feet field of view fire flame fluid focus freezing glass glottis hydrogen inch instance intense latent heat lens lenses less light liquid luminous magic lantern mass melting mercury merely metal mirror moon nature nearly nerally object obliquity oxygen painting particles passing perature perfect person picture piston placed produce proportion quantity of heat radiation rays Read the Analysis reflected refraction remarkable retina rising seen shadow shew snow solid spectator stance steam substances supposed surface telescope temperature thermometer tion transparent vacuum vanishing point vapour vessel visual angle warm whole winter
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Стр. 184 - ... destruction. On sending boats around to sound and to search, the place of entrance was again discovered, and was safely traversed a second time as an outlet from that terrible prison. On account of this bending of light from objects under water, there is more difficulty in hitting them with a bullet or spear. The aim by a person not directly over a fish must be made at a point apparently below it, otherwise the weapon will miss by flying too high. The spear...
Стр. 125 - ... of its intensity. Light passes from the sun to the earth in about eight minutes of time, as will be fully explained in a future chapter; and there is every reason to conclude that heat travels at the same rate. Human art can gather the sun-beams together, and...
Стр. 130 - ... iron ; and another class holding that heat is merely an affection or state of an ethereal fluid, which occupies all space, as sound is an affection or motion of air, and that the sun may produce the phenomena of light and heat without waste of its temperature or substance, as a bell may...
Стр. 201 - ... a lens weaker still might only destroy the divergence of the rays, without being able to give them any convergence, or to bend them enough to bring them to a point at all, — and then they would proceed all parallel to each other, as seen at e and...
Стр. 202 - Hence, when we wish to make experiments with parallel rays, we take those of the sun. Any two points so situated on the opposite sides of a lens, as that when either becomes the radiant point of light, the other is the focus of such light, are called conjugate foci. An object and its image formed by a lens must always be in conjugate foci ; and when the one is nearer the lens, the other will be in a certain proportion more distant. What is called the principal focus of a lens, and by the distance...
Стр. 180 - But for this fact, which to many persons might at first appear a subject of regret, as preventing the distinct vision of objects through all transparent media, light could have been of little utility to man. There could have been neither converging lenses as now, nor any optical instruments, of which lenses form a part, as telescopes and microscopes ; nor even the eye itself, which has its crystalline lens.