A Treatise On The Principles And Practice Of Dock Engineering

TIMBER. 149 Sål, or Saul, is a close-grained, straight-fibred wood, possessing the same luseful characteristics as the deodar, but much stronger and more durable. The wood is heavy and coarse in grain. Teak, perhaps the best known of Indian trees, is endowed with considér- able strength and durability. It has been designated the Indian oak, but it is also found in Burmah, Siam, and Java. The grain is fine and straight, the wood light and easily worked, with a tendency to splinter. Teak contains an aromatic oil of a resinous nature, which coagulates to such a degree of hardness as to spoil the edges of cutting tools. The oil is further reputed to be a preservative from the white ant and from sea- worms. Marketable logs do not exceed 40 feet in length, with a quarter- girth of 15 inches downwards. Teak is mainly used in small scantlings. Elm is a wood of great strength and toughness, found generally on the •continent of Europe and in North America. The grain is smooth, close, and fibrous, offering great resistance to crushing. English elm is brownish in colour, with a curly grain not easy to split, and it is a noteworthy feature that the sapwood is equally durable with the heartwood, provided the con- ditions be those of total immersion or complété dryness. Alternations of wet and dry bring about speedy decay. In American elm, which is lighter in colour, stringy in the grain, and liable to split under exposure, the heartwood alone is durable, and that only when kept constantly under water. Beech is a light, compact, fine-grained wood, grown in Europe and the United States. It is readily cleavable and easily worked. Like elm it is subject to decay under changes of condition, but is fairly durable if maintained in either the wet or the dry state. Oak is possibly the most valuable timber of northern latitudes, and Englisli oak is particularly renowned for its strength and toughness. It is unfortunately liable to the attacks of insects, and it contains an acid which has a tendency to corrode iron fastenings. American oak is considered somewhat inferior to the English and European varieties. Pitchpine is a product of the Southern States of North America. It is a strong, heavy resinous wood, extremely durable, when not exposed to marine insects, but difficult to work, and subject to cupshakes. It is procurable in logs, reaching up to 70 or 75 feet in length, with 10 to 20 inches quarter-girth. Pine, Deal, Fir, and Spruce are terms covering a large variety of timber ■of the same generic character, which it is not necessary to discuss here at -any length, more especially as the wood plays no part of unique importance in dock work. Its uses are confined to purposes common to most structures. It is a very handy material, with a considerable range of strength and toughness among the various species. It will be sufficient to remark that wood from the Baltic is generally superior to that from North America. Red pine from Scandinavia makes the best timber for framing, and spruce «deals from the same locality make admirable sheeting piles. The former is