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134 „,_ XI. THE ARCH MASONRY. CONSTRUCTION. off it right and left, as the bullets do off a cuirassier's breastplate, and will have no chance of beating it in. If still it be not strong enough, a farther addition may be made, as at c, now thickening the voussoirs a little at the base jdso. But as this may perhaps throw the arch inconveniently Ligh, or occasion a waste of voussoirs at the top, we may employ another expedient. § rv. I imagine the reader's common sense, if not his previous knowledge, will enable him to understand that if the arch at a, Plate III., burst m at the top, it must burst out at the sides. Set up two pieces of pasteboard, edge to edge, and press them down with your hand, and you will see them bend out at the sides. Therefore, if you can keep the arch from starting out at the points p, p, it cannot curve in at the top, put what weight on it you will, unless by sheer crushing of the stones to fragments. § v. Now you may keep the arch from starting out at p by loading it at p, putting more weight upon it and against it at that point; and this, in practice, is the way it is usually done. But we assume at present that the weight above is sand or water, quite unmanageable, not to be directed to the points we choose; and in practice, it may sometimes happen that we cannot put weight upon the arch at p. We may perhaps want an opening above it, or it may be at the side of the building, and many other circumstances may occur to hinder us. § vi. But if we are not sure that we can put weight above it, we are perfectly sure that we can hang weight under it. You may always thicken your shell inside, and put the weight upon it as at x x, in d, Plate III. Not much chance of its bursting out at j?, now, is there ? § vii. Whenever, therefore, an arch has to bear vertical pressure, it will bear it better when its shell is shaped as at b or d, than as at a: b and d are, therefore, the types of arches built to resist vertical pressure, all over the world, and from the beginning of architecture to its end. None others can ht compared with them: all are imperfect except these.
Title | The stones of Venice - 1 |
Creator | Ruskin, John |
Publisher | J. Wiley |
Place of Publication | New York |
Date | 1889 |
Language | eng |
Type | Books/Pamphlets |
Title | 00000159 |
Type | Books/Pamphlets |
Transcript | 134 „,_ XI. THE ARCH MASONRY. CONSTRUCTION. off it right and left, as the bullets do off a cuirassier's breastplate, and will have no chance of beating it in. If still it be not strong enough, a farther addition may be made, as at c, now thickening the voussoirs a little at the base jdso. But as this may perhaps throw the arch inconveniently Ligh, or occasion a waste of voussoirs at the top, we may employ another expedient. § rv. I imagine the reader's common sense, if not his previous knowledge, will enable him to understand that if the arch at a, Plate III., burst m at the top, it must burst out at the sides. Set up two pieces of pasteboard, edge to edge, and press them down with your hand, and you will see them bend out at the sides. Therefore, if you can keep the arch from starting out at the points p, p, it cannot curve in at the top, put what weight on it you will, unless by sheer crushing of the stones to fragments. § v. Now you may keep the arch from starting out at p by loading it at p, putting more weight upon it and against it at that point; and this, in practice, is the way it is usually done. But we assume at present that the weight above is sand or water, quite unmanageable, not to be directed to the points we choose; and in practice, it may sometimes happen that we cannot put weight upon the arch at p. We may perhaps want an opening above it, or it may be at the side of the building, and many other circumstances may occur to hinder us. § vi. But if we are not sure that we can put weight above it, we are perfectly sure that we can hang weight under it. You may always thicken your shell inside, and put the weight upon it as at x x, in d, Plate III. Not much chance of its bursting out at j?, now, is there ? § vii. Whenever, therefore, an arch has to bear vertical pressure, it will bear it better when its shell is shaped as at b or d, than as at a: b and d are, therefore, the types of arches built to resist vertical pressure, all over the world, and from the beginning of architecture to its end. None others can ht compared with them: all are imperfect except these. |
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