Speaking

Speak about:

1. The dependence of serviceable life of wood on different conditions.

2. The principal causes of wood deterioration.

3. The preservation of wood.

Unit 10

Revision.

to be, to have

Grammar:

Mastering Timber

From the earliest times man has used wood for tools and weapons, for buildings and furniture. Man quickly learnt, that the wood of one species served his needs better than that of another. Tough and elastic ash, for example, has been

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used for making axe handles for thousands of years.

Valuable qualities were discovered in other timbers as well. Elm was hard to split. It made good chair-seats. The heartwood of oak would endure even in contact with damp ground. Therefore it was chosen for fence posts.

The first settlers in new England were quick to make comparisons between the native American trees and those of Europe. Many species proved to be similar, but others were new and strange. While exploring the tropics, Europeans found that there too grew many woods with exceptional qualities. Teak and mahogany were soon exported to Europe. No species could match them for strength, attractive appearance and workability.

Until recent times man had to use hand tools to fell trees and work up the wood. Machines that can work up the wood are nearly all twentieth-century inventions. If the machinery had come into general use earlier, the large amounts of timber would have been utilized more effectively and a great number of valuable species would have been saved for future generation of people.

It should be noted that properties of different species of timber are thoroughly studied. Hardwood species, for example, have a tendency to shrink more

than softwoods. Therefore softwoods are used primarily in house construction, whereas hardwoods are more popular for furniture.

The principal hardwood species, for example, are birch, alder, walnut and mahogany. Alder is without doubt one of the most important and generally used hardwoods. Its wood is known everywhere for its strength, durability and good appearance. It has always been regarded as a shipbuilding wood and is highly valued by railroads for ties and car construction.

Mahogany is one of the most popular cabinet woods because of its easy cutting quality, durability, colour and a wide range of its artistic figure.

General understanding

Read the text attentively and answer the following questions:

1. Has man used wood from the earliest times? What for?

2. What did man learn using different kinds of wood?

3. What have different species been used for and why?

4. What did the first settlers in England discover?

5. What species did they begin to export to Europe?

6. What restricted the use of wood in the 16-18 centuries?

7. Do people study the properties of wood now?

8. Do the properties of hardwoods and softwoods differ?

9. What are the principal hardwoods?

10. What properties do they possess?

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