15. Find key words and phrases which best express the general meaning of each part.

16. Make a short summary of the text. Do it according to the following plan.

1. The title of the text is …

2. The text is devoted to …

3. The main idea of the text is …

4. It consists of …

5. The first part is about…

6. The second (third, fourth, etc.) part deals with …

7. The conclusion is that…

17. Read the following text and answer the questions below. Text b. Heating. Historical Development

Heating is process and system of raising the temperature of an enclosed space for the primary purpose of ensuring the comfort of the occupants. By regulating the ambient temperature, heating also serves to maintain a building's structural, mechanical, and electrical systems.

The earliest method of providing interior heating was an open fire. Such a source, along with related methods such as fireplaces, cast–iron stoves, and modern space heaters fueled by gas or electricity, is known as direct heating because the conversion of energy into heat takes place at the site to be heated. A more common form of heating in modern times is known as central, or indirect, heating. It consists of the conversion of energy to heat at a source outside of, apart from, or located within the site or sites to be heated. The resulting heat is conveyed to the site through a fluid medium such as air water, or steam.

Except for the ancient Greeks and Romans most cultures relied upon direct–heating methods. Wood was the earliest fuel used in places such as China, Japan, and the Mediterranean. Charcoal (made from wood) was used because it produced much less smoke. The flue, or chimney, which was first a simple aperture in the centre of the roof and later rose directly from the fireplace, had appeared in Europe by the 13th century. It effectively eliminated the fire's smoke and fumes from the living space. Enclosed stoves had been used by the Chinese about 600 bc and eventually spread through Russia into northern Europe and from there to the America. Benjamin Franklin invented an improved design known as the Franklin stove in 1744. Stoves are far less wasteful of heat than fireplaces because the heat of the fire is absorbed by the stove walls, which heat the air in the room, rather than passing up the chimney in the form of hot combustion gases.

Central heating has been invented in ancient Greece, but it was the Romans who became the supreme heating engineers of the ancient world with their hypocaust system. In many Roman buildings, mosaic tile floors were supported by columns below, which created air spaces, or ducts. At a site central to all the rooms to be heated, charcoal, brushwood, and, in Britain, coal were burned. The hot gases traveled beneath the floors, warming them in the process. The hypocaust system disappeared with the decline of the Roman Empire, however, and central heating was not reintroduced until some 1,500 years later.

Central heating was adopted for use again in the early 19th century when the industrial revolution caused an increase in the size of buildings for industry, residential use, and services. The use of steam as a source of power offered a new way to heat factories and mills, with the steam conveyed in pipes. Coal–fired boilers delivered hot steam to rooms by means of standing radiators. The advantages of hot water, which has a lower surface temperature and milder general effect than steam, began to be recognized about 1830.

Twentieth–century central–heating systems generally use warm air or hot water for heat conveyance. Ducted warm air has supplanted steam in most newly built American homes and offices. But in Great Britain and much of the European continent, hot water succeeded steam as the favoured method of heating; ducted warm air has never been popular there. Most other countries have adopted either the American or European preference in heating methods.

Notes:

hypocaust – подземная печь для отопления бань, комнат (в античную эпоху)

1. What is the primary purpose of heating?

2. What is direct heating?

3. Does indirect heating consist of conversion of energy into heat at the site to be heated?

4. Did the ancient Greeks and Romans rely upon direct–heating methods?

5. When did the chimney appear in Europe?

6. Where had enclosed stoves been used?

7. When was the Franklin stove invented?

8. What are the advantages of stoves?

9. Who became the supreme heating engineers of the ancient world with their hypocaust system?

10. What is the principle of hypocaust system work?

11. Why was central heating adopted for use again in the early 19th century?

12. Twentieth–century central–heating systems generally use warm air or hot water for heat conveyance, don`t they?