Essential vocabulary (II):

1. to resemble – напоминать, иметь сходство

2. external - внешний

3. helical – спиральный, винтовой

4. to revolve - вращаться

5. to shape – придавать форму, формировать

6. cavity - полость

7. bulky - громоздкий

8. robust – прочный, живучий

9. to mount – устанавливать, прикреплять

10. to wear – изнашивать, носить

11. rectangular vane- прямоугольная лопасть

12. curved – искривленный, загнутый

13. resultant - равнодействующий

14. fixed casing – зафиксированный корпус

Water-supply system (I)

Water supply system is an arrangement for transporting water from areas of abundance to an area of shortage. This includes works for the collection, transmission, treatment, storage, and distribution of water for homes, commercial establishments, industry, and irrigation, as well as for such public needs as fire fighting and street flushing.

There is much archaeological evidence to indicate that ancient peoples were concerned with their water supply. Wells were sufficient for small communities, and rivers provided enough water for civilizations along the Tigris and Euphrates, the Nile, and the Indus rivers; but as populations grew, wells had to be dug deeper, and water had to be brought in from more distant sources. These ancient systems included storage reservoirs at water sources, canals and aqueducts for water conveyance to points of use, and water-distribution systems. Highly advanced systems appeared about 2500 BC and reached their peak in the system supplying ancient Rome. The outstanding features of this system were the 11 aqueducts totaling 359 miles (578 kilometres) in length—of which 30 miles were supported on stone arches—that delivered some 50,000,000 gallons (189,000,000 litres) of water to the city daily. The water was distributed from large storage cisterns to public fountains and baths by an elaborate system of lead pipes.

During the Middle Ages, water supplies were largely neglected, and epidemics caused by waterborne organisms were common. In the 17^th and 18^th centuries, distribution systems utilizing cast-iron pipes, aqueducts, and pumps were installed in London and Paris. During the 19^th century the pollution of most water supplies became so serious that slow-sand filtration was initiated; and by the end of the century the realization that diseases could be transmitted by water led to the use of sterilizing chemicals, usually chlorine compounds.

Water sources for modern supply systems include wells, rivers, lakes, and man-made reservoirs. When points of use are near sources, direct intake can be used. Offshore intakes are sometimes built in lakes to obtain water of better quality and to avoid freezing problems in winter. Reservoirs are formed usually by constructing dams near the collection point of mountain-water runoff or across rivers. Dams provide a way of regulating water collection and flow so that the supply remains constant.

Essential vocabulary:

1. arrangement - размещение

2. abundance - избыток

3. shortage - нехватка

4. treatment - обработка

5. distribution – распределение

6. transmission - передача

7. flushing - промывание

8. establishment - создание

9. evidence - подтверждение

10. to indicate - указывать

11. to concern with smth./smb. – касаться чего-либо/кого-либо

12. well - колодец

13. sufficient - достаточный

14. dug – (от dig 1) копать, рыть

15. ancient - древний

16. conveyance – перевозка, передача

17. outstanding features -

18. elaborate – 1)разработанный, 2) сложный

19. lead - свинец

20. to neglect – пренебрегать, отвергать

21. to utilize - использовать

22. cast-iron pipes – чугунные трубы

23. pollution - загрязнение

24. to initiate - вводить

25. disease - болезнь

26. offshore - прибрежный

27. runoff - сток