Speaking

Speak about:

1. The role of wood in the life of people.

2. The main properties of wood as an "environmentally friendly" material.

Unit 2

Modal verbs.

Participles I, II.

Grammar:

Nature and Origin of Wood

Wood is a material that forms the trunks and branches of trees. Timber is wood cut from the trunk which can be used while constructing houses, boats, furniture and so on. The word "lumber" is used in the United States to signify sawn and worked timber.

As there are many thousands of different kinds of trees in the world so there is a great variety of woods, ranging from the very light such as balsa to woods so heavy that even being dry they sink in water. Man had to learn to choose those timbers most suitable for the purpose in hand. A tough wood was needed for his spears, for his bows elasticity was essential, while for his arrows straightness of grain was important. He learned from experience which timbers could endure in the soil and which could be fashioned into boats.

In some northern countries where only a few kinds of tree grew the choice of wood was very limited. In tropical forests, on the other hand, the choice was bewildering, and so, as trade between countries developed, timbers were exported from the places where the trees grew to other countries that had no forests or lacked the particular kinds of wood required. Valuable ornamental woods such as ebony and sandalwood had to be carried great distances to adorn houses and furniture of the wealthy.

Until fairly recent times wood and charcoal made from it were the principal fuels used for cooking and heating. And this is still true in some countries.

Traditionally woods are classed either as "softwoods" which means woods

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from coniferous trees that bear needles or as "hardwoods" meaning those from

the broad-leaved trees. The woods from conifers are in fact softer than those from broad-leaved trees and this was in general true of the timbers of Europe where the spruces and pines yield timbers that can be easily cut and nailed, while broad-leaved trees such as oak and beech produce harder and heavier woods.

Trees grow upward by elongation of the terminal shoots until they reach their maximum height. At the same time their girth increases by the addition each

year of a layer of new growth below the bark. The form that the mature tree develops depends very much on its surroundings. The way trees are grown can thus affect the timber that can be obtained from them and the forester attempts to grow trees that will provide the kind of timber the timber merchant will require.

When a tree is felled the butt end is stouter than the upper end since for many years the tree grew in girth at the butt. The taper of the log again depends on the way in which the tree grew. The less the degree of taper the more long straight planks will the saw miller be able to obtain from it.

General understanding

Read the text attentively and answer the questions:

1. What is wood?

2. What is timber?

3. What does lumber signify?

4. How did man choose among a great variety of woods?

5. What did man learn from experience?

6. Where were timbers exported?

7. How are woods classed traditionally?

8. What is the difference between "softwoods" and "hardwoods"?

9. What is the difference in properties of these two classes?

10. What can affect the timber that can be obtained from trees?