Elementary Principles of Carpentry

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E. & F.N. Spon, 1871 - 517 páginas
 

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Página 351 - Hesiod to the same effect ; and adds, " as the houses of the ancients were so smoky, it may be easily comprehended how, by means of smoke, they could dry and harden pieces of timber.
Página 336 - In trees that have not arrived at maturity, the hardness and solidity of the wood are greatest at the heart, and decrease towards the sap-wood; but in the mature or perfect tree the heart-wood is nearly uniform; while that of a tree on the decline is softer at the centre than it is next the sap-wood. These observations were made by Buffon in the course of his numerous experiments, and also by Duhamel. Of Felling Timber. 318. "It should be," says the venerable Evelyn, fj in the vigour and perfection...
Página 173 - Tredgold gives also the following rule for the rafters as more general and reliable: Multiply the square of the span in feet by the distance between the principals in feet, and divide the product by 60 times the rise in feet ; the...
Página 22 - A solid (Fig. 4) which has a polygon for a base, and the rest of whose surface is formed of triangles which terminate in a common point called the vertex, is a pyramid. NOTE. — The triangles form the convex surface of the pyramid. When the base of a pyramid is a regular polygon, and a line drawn from the vertex to the middle of the base is perpendicular to the base, the pyramid is a regular pyramid.
Página 68 - ... the square root of the quotient will be the diameter of the pump plunger in inches (allowing 5 per cent.
Página 303 - Beams to resist cross strains require to be lengthened more frequently than any others, and, from the nature of the strain, a different form must be adopted for the scarf from that which is best for a strain in the direction of the length. There are cases where beams are exposed to both strains at the same time, but the cross strain is generally that of the most importance. Of this we have an example in the...
Página 8 - Consequently, if a body be kept at rest by three forces, and any two of them be represented in magnitude and direction by two sides of a triangle, the third side taken in order will represent the magnitude and direction of the other force.
Página 446 - Rialto, which was built in 1591, or 280 years ago. But it soon rots when exposed to the weather, or to damp ; and in a dry state it is much subject to worms. On account of the durability of alder in water, it is esteemed valuable for piles, planking, sluices, pumps, and in general for any purpose where it is constantly wet. And for such purposes it has been much cultivated in Holland ancr* Flanders. It is also used for turners' wares and other light purposes.
Página 113 - ... to the bulk or weight of the beam, whether it be shorter or longer, narrower or wider, shallower or deeper, solid or hollow. Thus, a beam 10 feet long will support but half as great a pressure without breaking, as a beam of the same breadth and depth which is only 5...

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