The principles of architecture, Band 2

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Seite 36 - ... on their surfaces, and the medium through which they are seen, is called keeping. 1. When objects are removed to a great distance from the eye, the rays of light which they reflect will be less vivid, and the...
Seite 36 - ... 5. From the closeness or openness of the place where the object is situated, the light, being much more variously directed, as in objects which are surrounded by buildings, will be more deprived of reflection, and consequently will be darker than those objects which have no other objects in their vicinity ; except the surrounding objects are so disposed, as to reflect the rays of light upon the surrounded objects.
Seite 59 - ... from falling upon them, those parts of the mouldings which are in shade will become visible ; for, besides a reflection from the ground, there will be a strong reflection from the surface of the building, immediately under the mouldings or ornaments. It has already been observed, that these rays will be reflected in all directions, and, consequently, a part of them will be reflected upwards on the mouldings above, and, therefore, will show light and shade on the mouldings according as the reflected...
Seite 61 - ... cylinder or column is attached to a wall in a vertical position, and if it has any projecture over it, so as to cause that part under the projecture to be in shade quite round the cylinder, there will not only be a reflection from the wall on the contrary side of the cylinder, to the sun upon that side of the cylinder which is next to it, but also from that part of the wall on that side of the cylinder next to the sun, which will make that part of the cylinder which is in shadow, lightest at...
Seite 38 - DEFINITIONS. 1 . A body which is continually emitting a stream of matter from itself, thereby rendering objects visible to our sense of seeing, is called a luminary ; such as the sun or any other body producing the same effect. 2. The stream of matter which is emitted from the luminary, is called light. 3. A substance or body which light cannot penetrate, is called an opaque body. 4. If a space be deprived of light by an opaque body, it is called a shade. 5. The whole or part of any surface on which...
Seite 39 - ... will reflect the rays of the sun in as many different directions. DEMONSTRATION. If any ray fall upon a part of the surface which is perpendicular to that ray, it will be reflected in the same line as the" incident ray ; but the more or less any part of the surface is inclined to a ray, falling upon that part of the surface, the greater or less angle will the reflected ray make with the incident ray. For, imagine a perpendicular to be erected to that part of the surface where any incident ray...
Seite 39 - IV. Any uneven -reflecting surface, whose parts lie in various directions, will reflect the rays of the sun in as many different directions. DEMONSTRATION. If any ray fall upon a part of the surface which is perpendicular to that ray, it will be reflected in the same line as the incident ray ; but the more or less any part of the surface is inclined to a ray falling upon that part of the surface, the greater or less angle will the reflected ray make with the incident ray. For, imagine a perpendicular...
Seite 2 - ... describe an arc ba, and it is done. FIG. 5. To describe a cimarecta, the projections at a and b being given. Join ab; bisect it at e; then on the points a and b describe arcs meeting each other on the opposite sides at с and d : on the points с and d; with the same radius, describe the opposite curves ae and ed, and it is done. FIG. 6. The cimareversa is described in the same manner, but in an opposite direction.
Seite 79 - В b at b ; then on В as a centre, with one half of С D, describe a part of a circle, as is shown by the dark line, and it will be the edge of the shadow. Much in the same manner may the shadow of a recess, which has a back parallel to the plane of the wall, be found, as is shown at Fig. 2. PROBLEM III.
Seite 68 - ... prevent a part of the reflected rays from proceeding to the plane behind the prism, and consequently the plane would be something darker than the face of the prism, which is parallel to it ; but the side of the prism adjoining to the plane will throw a reflection upon the plane, and therefore it...

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