Механизация производственных процессов. - 34 стр.

6. He was to come to the conference.
7. They will have to discuss this question.
8. You ought to help her.
9. She must use a dictionary at the lesson.
10. The students are to come to the laboratory.

                                The Steam – Engine
        Long ago people noticed that steam has the power of moving things,
and they began to wonder how steam could be made to work for them. The first
steam-engine was made in ancient Egypt by Hero, a philosopher of Alexandria.
It consisted of a hollow globe, which could turn on a pair o pipes and was
supplied with steam through one of them. The steam escaped from the globe to
the outside air through two bent pipes facing tangentially in opposites
directions at the ends of a diameter perpendicular to the axis. The globe
revolved by reaction from the escaping steam.
        Hero(s engine, called the aeolipile and described in his work
“Pneumatica” was regarded merely as a toy. In fact, it was seventeen hundred
years before anyone showed any further interest in the idea of a steam-engine.
        The earliest steam-engine which found employment in industry was that
of Thomas Savery in 1698. The engine was used in pumping mines and I
raising water to supply houses and towns. A serious difficulty with this engine
was that the height which it would lift water was limited by the pressure the
boiler could bear.
        There were even explosions, as the safety valve had not yet been
invented. This was invented by the Frenchman Denis Papin, who was also the
inventor of the piston.
        The next step forward was taken by the English mechanic Thomas
Newcomen,         who      combined the ideas of Savery and Papin. It was
Newcomen who designed an engine that could be used not only to pump water,
but also to drive other machinery.
        An even better steam- engine was built in Russia in 1765 by the brilliant
mechanic Ivan Polzunov. One of the reasons why it was better was that it could
be used for many purposes and not just for pumping water. Secondly,
Polzunov(s engine had two cylinders. Hence, while the piston in one was going
down, the piston in the other was rising. It was therefore the first continuous-
action engine.
        The next inventor who helped to make the steam-engine what it is today
was James Watt, a maker of instruments at the University of Glasgow. The
legend is told is that Watt invented the modern steam-engine by watching the
steam lift the lid of his boiling tea-kettle. This, of course, is not so. Watt began
improving the steam-engine, when one of Newcomen(s engines was brought to