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THE MICROSCOPE

Even the ancients had known that curved mirrors and hollow glass spheres filled with water had a magnifying effect. In the opening decades of the 17^th century men began to experiment with lenses in order to increase this magnification as far as possible. In this, they were inspired by the great success of that other lensed instrument, the telescope, first put to astronomical use by Galileo [galə'lāō] in 1609.

Gradually, enlarging instruments, or microscopes (from Greek words meaning "to view the small") came into use. For the first time the science of biology was broadened and extended by device that carried the human sense of vision beyond the limit. It enables naturalists to describe small creatures with detail that would have been impossible without it, and it enabled anatomists to find structures that could not otherwise have been seen.

The first man, who made and used microscope was Anthony van Leeuwenhoek ['lāvən,hook; 'lāyən-]. He was not a professional scientist. In fact, he was a janitor in the city hall in Delft, Holland. He made more than 200 different microscopes, most of which had only one carefully polished lens. With his homemade lenses, he explored all sorts of things and discovered a world never before seen by the eyes of man. He examined milk, water, insects, the thin tail of a tadpole, and many other objects. His discoveries of bacteria, blood capillaries, blood cells, and sperm cells made him famous. In 1675, he wrote the first description of the microscopic animals that live in water. Leeuwenhoek's microscopes were simple. But his great patience and keen powers of observation brought to light many new facts about living things.

THE MODERN MICROSCOPE. The microscopes of today are far more complicated than those of Leeuwenhoek's time. They are called compound microscopes because they contain more than one lens. At the top there is an eyepiece which has two lenses in it. Then there is a long tube with more lenses at the bottom. These are called objectives. You can choose different magnifying powers by swinging different objectives into position. The usual high school microscope has a choice of two powers. With the low power, you can magnify an object about 100 times. The high power objective with the usual eyepiece can enlarge things up to 500 times.

If you wish to examine an object under the microscope you must pass a beam of light through it. As the light passes through the lenses, it is bent in such a way that a magnified image appears. For this reason, anything you wish to see must be very thin. If it is too thick, the light will not go through it. Most microscopes have a mirror at the base. This can be moved in any direction. It reflects light up through the object and the lenses. The object, mounted on a piece of glass, is placed on a flat platform called the stage. Then the microscope is adjusted by moving the tube up or down. This places the objective at the correct height above the object. Unless you focus carefully in this way, you can not get a clear picture.

THE ELECTRON MICROSCOPE. There is a limit to the magnifying power of the compound microscope. The very best of them can enlarge an object up to 4000 times. In recent years a new type of microscope has been invented that does not use light. Instead, beams of electrons are passed through the object and a picture is made on film. The electron microscope can give us an image 25,000 times larger than the object. This development illustrates an important principle of science: when a new instrument is invented, it may speed up discoveries in the laboratory. Already, the electron microscope has made it possible to see things never dreamed of by Leeuwenhoek. We may be sure that in the future it will continue to reveal many new secrets of nature.

Notes to the text:

to graduate from – закінчувати вищій навчальний заклад

a graduate – випускник

to a certain extent – до певної міри

to a great extent – в значній мірі

to a full extent – у повній мірі

in all appearance – цілком очевидно

3. Translate the following words bearing in mind the meaning of the affixes and memorize them:

to magnify (v), magnifier (n), magnification (n)

to increase (v), increase (n), increasing (adj), increasingly (adv)

to decrease (v), decrease (n)

to inspire (v), inspiration (n)

to graduate ((v), gradual (adj), gradually (adv)

to extend (v), extension (n), extensive (adj), extensively (adv)

to explore (v), explorer (n), exploration (n), explorative (adj)

vision (n), visionary (n) (adj), visibility (n), visible (adj)

to observe (v), observer (n), observatory (n), observant (adj), observance (n)

to complicate (v), complication (n)

to reflect (v), reflector (n), reflection (n), reflective (adj)

to invent (v), inventor (n), invention (n), inventive (adj)

to appear (v), appearance (n)

to disappear (v), disappearance (n)

4. Underline the prefixes in the following words and translate them:

to discover, invisible, unknown, to exclude, indifferent, unnatural, to mislead, impossible, independent, irregular, nonliving, disorder; illegal

5. State to what part of the speech the words belong and translate them into Ukrainian; form the corresponding verbs:

difference, assimilation, respiration, reproduction, organization, movement, magnification, resemblance, relation

6. Form the nouns corresponding to the following verbs:

to discover, to construct, to affect, to know, to develop, to vary, to divide, 'to differ, to resemble, to observe, to suggest, to apply, to encourage, to agree, to magnify, to appear

7. Translate the m following sentences into Ukrainian paying attention to the emphatic construction "it is... that";

1) It was the electron microscope that finally revealed them as objects that could be seen.

2) It is the absence of vitamins that brings on diseases.

3) It is very important to begin the experiment in time.

4) It is the magnifying power of lenses that made it possible to see tiny things.

5) It was Carolous Linneus who suggested the first system of classification of living things.

6) It is necessary to use only very thin objects to see them under the microscope.

7) It was the new method of investigation that helped to finish the work so successfully.

8) Anton von Leeuwenhoek was the first man who penetrated through his lenses into the world of the microscope.

8. Answer the questions:

1) Explain how a microscope is used.

2) What kinds of microscope do you know?

3) What is a compound microscope?

4) How does the electron microscope differ from the compound microscope?

5) Why are most compound microscopes more powerful than simple microscopes?

6) How will you examine an object under a compound microscope and an electron microscope? What is the difference?

7) Why can't you see cells or protoplasm when you put your finger under the microscope?

9. Read the following text and try to retell it word for word:

By examining water from a lake or stream we will find that it is full of life. If you look carefully, you may find there the simplest animal, the ameba [ə'mēbə]. It is a tiny mass of jelly usually about 1/50 of an inch long. The ameba is surrounded by a very thin cell membrane, which is quite elastic. At times, a part of the membrane will push out, forming a false foot. The rest of the ameba will then flow into it. In this way, the little animal moves slowly about in its watery world.

10. Read and translate the following text; say what new information about plants and animals you got from it:

Anton von Leeuwenhoek lived all his life in Delft. He had hardly any education and never learnt Latin, which in those days was the mark of an educated man. He worked when a boy as a clerk in a dry-goods shop. Part of his duty there was to examine textiles with a fine hand lens. Sometimes he placed the lens over other substances besides cloth — the skin of his own hand, the fiber of the wood on the table. Later on in his spare time he used to go to the spectacle makers and he learnt from them how to polish lenses. Afterwards he began making lenses himself.

The lenses he made were precise and beautiful. Altogether he made 247 instruments and some of them would increase the size of a minute object as much as 270 times.

After he had learned something about metalwork he could mount them. When he was about forty he became so interested in everything seen through his lenses, that he spent much of his time looking through his microscopes.

One day he had focused his microscope on a drop of water from a rain barrel and had found in it to his great astonishment "little beastics" as he called them, swimming about, He had found these little creatures not only in rain water, but in pond water, in the secretions of various animals, even in the saliva of his own mouth. Examining different objects he continued to find ail manner of strange little organisms, although he did not realize, that they might have any connection with diseases. Only in the 19th century Louis Pasteur developed and demonstrated by his experiments the germ theory. But it was Anton von Leeuwenhoek's discovery of microbes that started a new field of scientific investigation.

11. Translate the text into Ukrainian and then back into English, compare your version with the original:

In science one of the most important discoveries having a great influence on the development of science was the fact that microscope has come into common use among scientists. The microscope gave scientists new power. Now they could see things that had been hidden. The first microscopes were very simple. They had only single lenses, some had double lenses with a tube between them. Anton von Leeuwenhoek was the first man who penetrated through these lenses into the mysterious world of the microbe. No one before his time had guessed that such tiny organisms existed.

12. Compose short dialogues for the following imaginary situations:

1. You know that Leeuwenhoek was not a professional scientist. Yet he corresponded with the Royal Society in London, where he sent his descriptions of what he had seen through his microscope. One day he was visited by one of the members of the Royal Academy. Try to imagine the conversation that might have taken place.

3. You are a teacher of zoology. This is your first lesson on the use of microscope. Instruct the students in its use.

4. Your younger sister comes up to you and asks what a microscope is. Tell her what instrument it is, how it is constructed and what it is used for.

5. You are going to make a report "From Leeuwenhoek to the present". What will you include in it?

6. You are given a microscope without a mirror and asked to examine a leaf of an apple-tree. Will you be able to do it? Discuss it with your friend.

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