(1) The ancient Greeks are known to have used water clocks for timing the speeches of their orators. The simplest water clock consisted of a vessel of water with a small hole in the bottom. Filled up to a certain mark, the water gradually escaped out of the hole in approximately the same intervals of time.
(2) Next, the inventive mind of man produced the hourglass, or sandglass.
(3) The first true clock, from the modern point of view, appeared in the 14th century. Earlier clocks had neither hands nor face and told time merely by striking the hour. Bells were struck by hammers held in the hands of little mechanical figures.
(4) As the time passed clocks were improved, the pendulum being introduced into the clock mechanism by Christian Huygens (1629-1695), a famous Dutch scientist. That improved the accuracy of clocks so much that it became possible to measure not only hours but minutes as well.
(5) The early clock developed into a watch of a portable size made in the form of books, animals, fruit, stars, flowers, etc. During the 17th century the watches were still more improved by the use of jewels for bearings, which reduced friction and increased regularly of the running of the watch. It was little by little that the watch reached its present day perfection.
Exercise 2 Answer the following questions.
1. What is the text about? 2. According to what are our clocks timed? 3. How are pendulum clocks protected from outside influence? 4. What are the observatories’ time signals based on? 5. What standard unit of time do you know? 6. When was standard time extended to the entire world? 7. What time has been taken as the zero point? 8. Why can the atoms be used to measure time? 9. What clocks have the ancient Greeks used? 10. When did the first true clock, from the modern point of view, appear?
Exercise 3 Translate and memorize the following expressions from the text.
Earth time, the earth’s rotation, to set a clock, outside influence, pendulum clocks, to pump out the air, air resistance, different direction, the observatories’ time signals, vacuum tubes, a fraction of a second, X-ray pictures, a man-made thing, complete turn, zero point, precise frequencies of oscillation, crystal’s vibrations, to run a clock, to time the speech, the accuracy of clocks.
Exercise 4 Find synonyms among the following words.
Accurate (adj), call (v), rotation (n), task (n), carry out (v), various (adj), determine (v), average (adj), keep (v), protect (v), affect (v), happen (v), instrument (n), locality (n), zero (n), precise (adj), name (v), revolting, problem (n), fulfil (v), different (adj), define (v), middle (adj), preserve (v), defend (v), influence (v), take place (v), tool (n), place (n), naught (n).
Exercise 5 Write a summary of the text, presenting the content of each paragraph in 2-3 sentences. Use the expressions:
The main idea of the text is … The text deals with the one of the most important (urgent) issues … Much attention (consideration) is given to (classification, description) … It focuses on the matter of … The text gives an overview of … The text is mainly concerned with … The aim of the survey is to show (demonstrate, find) … Particular emphasis is given to the analysis of… The text gives a detailed analysis of (reports on) … To sum up … In conclusion …
Индивидуальное задание для студентов заочного отделения к курсу
«Английский язык»
Вариант № 22/3c
Exercise 1 Read the text and translate it in written form.
Solar power
(1) The sun’s energy manifests itself as thermal, photo-electric and photo-chemical effects. Men have tried to use solar energy since earliest times, but no means existed to generate useful power from the sun’s heat until steam and hot-air engines were invented.
(2) Crude devices for heating water by solar energy date back many years, and production of salt by solar evaporation of sea water is probably the most ancient of man’s sun-activated processes. Photo-electricity has been known for almost a century, and millions of selenium photo-cells have been used as light-meters and in similar application.
(3) Most fundamental of all thermal solar processes is the simple fact that, when sunlight falls upon a surface of any kind, the surface becomes warmer than the surrounding air. The extent to which the surface temperature rises depends upon many factors, most important of which are the angle between the surface and the sun’s rays, the absorptive of the surface and the precautions taken to prevent the surface from losing the absorbed heat.
(4) The angle effect is caused by the fact that the sun’s rays travel in straight lines. When a surface is perpendicular to the rays, their intensity is at its maximum; the surface being horizontal, the radiation intensity drops off and reaches its minimum.
(5) The most effective way to minimize the loss of energy from the sun heated surface is to cover it with one or more sheets of a glass-like material which is transparent to the sun’s rays but opaque to the longer wave lengths emitted by the warmed surface. The air space between the surface and the glass is an effective prevention of heat loss by convection.
(6) A flat place of blackened metal covered with one or more transparent sheets of glass or plastic is known to be the simplest collector of solar energy. Once collected, heat can be used in a variety of ways. Here are some of the potential and actual applications.
(7) Space heating is probably the most important, since nearly one-third of our energy supply is used for this purpose. Water heating can be achieved by portable solar heaters which are able to give as much as 400 litres of boiling water on a sunny day.
(8) The distillation of sea water is another process to be accomplished by variations of the simple flat plate collector. The production of temperatures low enough for air conditioning and domestic refrigeration is a very important potential use of solar energy which is only now beginning to receive the attention it deserves.
(9) Typical arrangements of concentrator-type solar plants with high-pressure boilers must be able to track the sun, so that its rays can be focused upon a collection-element.
(10) When physicists discover a new way to generate electricity directly from radiation, without going through the thermal cycles both nuclear and solar power will move forward rapidly. Until that time solar units will probably continue to be relatively small and applicable only to special purposes such as irrigation and power production in isolated locations.
(11) We believe solar radiations to be an immense and inexhaustible source of energy our world possesses. UP to the present time, mankind has been able to produce energy from the earth’s fuel, but the time will come when this energy will be scare and hence expensive. Research is needed now to learn how to use solar energy cheaply and effectively to heat and cool our homes, produce fresh water from sea water, and to generate large blocks of electric power.
(12) Do you know that the energy of the sun’s rays is known to have been used from ancient times?
(13) One of the Egyptian statues was said to produce sounds every morning to greet the rising sun. The secret of the singing statue has been discovered.
(14) The inside of the statue was divided into two parts. The lower part was filled with water and the upper one with air. One section of the chamber was situated against the eastern wall of the statue. When the sun rose, it heated the air in the upper part of the statue. The air expanded, pressed on the water and forced it into the other section of the chamber. The water, in turn, forced out the air and sent it through pipes of different musical tone, producing various sounds.
