The vast extent of the regions of the East Indies, their various climates and physical conditions, render it impossible that the same tree ca. n pro duce the identical quality of timber m every locality where it grows. As au instance of this may be cited the majestic teak, which grows to an immense height in Malabar, on the Godavery, in Pegu and Tenasserim, and may be seen In the mountains of Bundelkhand, but is there only in the form of a moderate-sized shrub ; and even where it presents the same form of a gigantic tree, as Malabar and Pegu, the quality of the timber. it yields is dissimilar. The timber of trees which grow in moist and shady places is not so dose, substantial, or durable as that, which comes from a more exposed situation.
The preservation of timber naturally arranges itself into the preservation of growing timber, and that of timber when felled. The preservation of growing timber is an art of considerable import ance, and is cultivated in countries where timber is comparatively scarce.
The practice of thinning out plantations is of value, not only as affording a supply of wood, but, by admitting an increased supply of air and light to the remaining trees, their growth is greatly promoted.
Since the close of the 18th century, it has been an increasing belief that the climate of a country is greatly modified by the scarcity or abundance of its trees and forests. Forty years a„,cro, in 1845, Assistant-Surgeon Balfour furnished the Madras Government with a memorandum of all existing information on this subject ; it then became a matter of inquiry by a committee of the British Association ; and it is now generally recognised that trees exercise a powerful influence ' on the climate of the region or district in which they grow. In a tropical country like India, therefore, the preservation of existing trees, and their exten sion in arid districts,isamatter of much iinportance. Dr. Cleghorn, in a report for 1860, suggested that the high wooded mountain tops overhanging the low country (such as lloolicul) should be pre Served with rigid care, and the forest there not be given over to the axe, lest the supplies of water be dhninished. In order that the course of the rivulets should be overshadowed with trees, the hills should be left clothed to the extent of about half of their height from the top, leaving half of the slope and all the valley 'below for cultivation.
Teak is a ship-building wood; teak, sal, padouk, _etc., are recognised ordnance woods; Trincomalee, ChitfAgong, and Coromandel rosewood, redwood, satin-wood, sandal-wood, snake-wood, mahogany, ebony, kyaboca, zebra, and tulip are furniture or fancy woods.
By far the greater part of the ornamental woods are derived from trees. There are, however, some remarkable exceptions. The wood of roots is different in structure from the wood of stems, and the same tree may furnish two very different kinds of ornamental wood, according as they are derived from its ascending or its descending axis. The wood of the inner portions of a stem may be of very different colour and quality from that of its outer parts. In the immediate neighbourhood of the origin of branches, it may exhibit varieties of pattern, such as to render it greatly more orna mental than elsewhere, and m some cases, when under the influence of morbid growth, reveals additional beauties, so as to be prized for qualities which in nature are defects. If a cross-cuttiug of teak, or oak, or mango be compared with a like portion of palmyra wood, the differences between them will be seen strongly contrasted. In the former, the layers of wood are ranged in concentric circles round the central pith, and are encased externally in a binding of bark, itself composed of distinct and differently organized portions. In the latter there is a uniform appearance through out the section, the siffistance not being disposed in concentric ring-s, but appearing as if a bed or ground of one kind was studded with specks of another order of tissue. These dissimilarities indicate differences of the greatest structural im. portance in the economy of the respective trees Corresponding with them are peculiar modifica tions of every portion of the plant's organization. Also the external aspect of the plants of either, type is altogether unlike that of the other. 'Rd appearance styled silver-grain in wood is depend ent on the cellular tissue of the medullary rays and is therefore exhibited by exogenous wood. only. It gives the streaks the glancing satin) lustre so ornamental in many kinds of woods. Iti the oak and beech this appearance is conspicuous. The inner layers of wood, after the tree has be come aged, often become compact, and frequently1 different in colour from the new wood. They arc then styled the heart-wood. Botanists term them the duramen, and apply the narne alburnum to the outer layers or sap-wood. In the former the tissues have become dry and dense, and charged with solidifying deposits, so as to prevent them aiding in the ascent of the sap. Often, too, they become more or less deeply coloured, so as con spicuously to contrast with pale sap-wood. This difference is especially conspicuous in the ebony tree, the black portion of which is the duramei or heart-wood. In the oak they resemble ebony.