The main economic value of timber, apart from considerations of strength, durability, texture, ani colour, will depend on the quantity in which i can be produced for tho many purposes for whicli timber is indispensable ; and in countries destitut ' of coal, the supply of fuel for manufactories, rail ways, and steam flotillas, as well as its domesti consumption, is an itnportant item in the considera tion of timber resources. The most importau application of wood is in the building and repair iiag of houses and ships, and in the constructim of machinery. For these purposes the larger tre which come under the denomination of timber ar employed. In the moist climates of Southern an Eastern Asia, trees grow to a majestic height, but others are so destitute of verdure that even the castor-oil plant is valued for construction.
For all practical purposes, those woods appear to be best in which the cells are lined with resin ous matter ; those filled with hygroscopic gummy matter are for the most part of less value ; they are seasoned with difficulty, and are always more liable to decay. The best woods are those having a strong fibre, protected from all external influ ences by a coat of resinous matter, or at least of a matter insoluble in water, and one which does not attract atmospheric moisture.
Some trees, while growing, secrete large quan tities of silica, which is deposited in hollows or in the interstices of the woods. The tabashir of the hollow bamboos is a well-known example ; the tamarind tree has so many portions of silica in its stem, that the carpenters of the E. Indies object to work it ; and masses of silica, of considerable size, have been got froin the teak logs.
Tetrk..—In the years 1880-81 to 1882-83, the value of the teak exported from India ranged from 50 to 61 laklis. That of other timbei, with ebony and sandal-wood and other kinds, was 4} laklis, sandal wood in 1883 being Rs. 4,02,931.
In tho years 1880 to 1882, the timbers and woods of kinds imported into Great 13ritain under the designations hewn, sawn, split, planed, dressed, staves, and mahogany, ranged in value front ten to twenty millions sterling ; those from British North America, Germany, Norway, Russia, Sweden, and other countries, ranged in valuo from £14,956,547 to £17,168,300.
Teak when young grows very rapidly. Trees ten years old have usually a girth of eighteen inches, measured at six feet front the ground ; at twenty two years, a girth of three feet is attained; but full grown trees of nine feet in girth cannot be supposed to be less than 160 years old.
The strength and density of teak timber vary exceedingly, according to the locality where the tree is grown. The extremes observed in pre
liminary experiments were 40 and 50 lbs. per cubic foot, and 190 to 289 lbs. breaking weight. Mala bar teak is by common consent ranked higher for naval purposes than Tenasserim or Pep timber. The cause of its greater durability and power of resisting dry-rot, appears to depend chiefly on its more oily or resinous quality, and the greater density arising from its slow growth on the sides of hills. In Burma, the best teak-growing districts are Pegu on the Irawadi and Sitting rivers and in the Thoungyen valley, comprising 7312 square miles of forest Tenasserim and Martaban include 520 square miles of jungle on the Salwin river banks. But even these forest,s are poor compared with the extensive tracts covered with t,eak to the north of the British boundary, especially on the feeders of the Siting and. Salwin rivers, and some of the tributaries of the Meinam or Bankok river. The trees also are, as a rule, much larger, and the shape of the stein more regular, in the forests of the Barmese empire, the Siamese king dom, and the Karennee country. The tallest teak tree measured in Pegu was 10G feet high to the first branch.
Sal.—In Central India, on the Nerbadda river, extensive sal or saul forests begin to take the place of teak, which does not occur farther north than Jhansi. Along the whole Sub-Himalayan range up to 3000 feet elevation, and in a belt range from five to twenty miles wide at the foot of the hills, and over 1600 miles long, dense forest is found. Wherever the soil is elevated and dry, this is pure sal forest. In Karaaon, Oudh, and many other of the Nepal jungles, as many as seventy first-class trees per acre have been found, besides young trees from seed, at 200 or 300 per acre, growing up with the old. The ferry-boats used on thei Gogra' and other affluents of tho Ganges are formed of single logs hollowed out and floated down from Nepal, one of which holds ten to fifteen men, with cattle and horses, costing £6 to £10, purchased from the Nepal boat-makers. Sal timber (Shorea robusta) is close - grained and heavy, but does not appear to be very durable, and on that account is inferior to teak ; but in strength it surpasses the latter, and deserves to be considered the second best timber tree in India. The British sal forests may roughly be computed as follows:—Central Province, 2000 square miles; Kaniaon and Garltwal, 600 ; Dehra Doon and Bin lore, 400 ; Oudli, 230 ; Gorakhpur, 300. Both sal and teak trees take 100 years to grow.