1. Comprehension questions:

1. What is an underground surveying based on?

2. What does working in the dark require?

3 How is working in constricted places conducted?

4. How is visibility in mine surveying assured?

5. When is auxiliary telescope required?

6. Is a higher degree of accuracy required in underground surveying?

7. Why arc more refined methods required in mine surveying?

8. What is a special problem in mine surveying?

2. Group activities:

a) discuss peculiar conditions of underground surveying,

b) name devices used in mine surveying

3S Express the main idea of the text in the shortest possible way.

UNIT3

Text В How to interpret aerial photographs

/. Read aloud and memorize the following words:

aid-art-bound(v)-

examination -. extreme -ground -. identify -ідентифікувати image -

interpretation -інтерпретація object -

допомога

мистецтво

обмежувати, межувати

огляд, дослідження

крайність, край

грунт

розпізнавати, пізнавати,

зображення тлумачення,

об'єкт

//. Expressions for the text comprehension:

a great deal -

best of all -cultivated field -

curved line -irregular edge --keep in mind -man-made features -

характеристики natural feature

багато

найкраще всього оброблюване поле крива лінія нерівний край пам'ятати штучні риси,

природня риса,

print - відбиток, фотокартка

reflect - відображати, відбивати

relief- рельсф

result (v) - мати результатом,

закінчуватись

scale - масштаб, мірило

shadow - тінь

shape - форма

size - розмір

skilled - кваліфікований

stereoscope - стереоскоп

tone - тон

особливість

photo interpretation - тлумачення,

інтерпретація - фото

reading glass - лупа, збільшуване скло

shadow of gray—shade of gray ~ сіра тінь

source of light - джерело світла

straight line - пряма ліній

take picture - зняти фото

visible details - видимі деталі

How to interpret aerial photographs

Photo interpretation is the art of identifying visible details from their images on a photographic print. The best aid to this is the stereoscope. However it is easy to become skilled in this work by examining single photographs.

A reading glass will help a great deal. Skill will come by examining all types of photographs and comparing them with maps or, best of all, with the ground itself. Start with prints with a scale of 1:20 000 or larger.

Interpretation requires the study of three things: i) tone, 2) light and shadow, 3) shape and size.

Tone. A large amount of light reflected from an object results in a white object on the print, and no light results in a black object. In between these two extremes are all the shadows of gray.

This shade of gray of an object is known as the tone of the image. The less light reflected the darker will be the shade of gray, or the darker the tone,

Light and shadow. When studying the photographs always remember about the source of light and have the shadows on the print fall toward you.

This puts the light in the same position the sun was in when the picture was taken.

This is very important when studying relief.

Shadows often give the shape and size of an object that appears on a photograph. The top of a square building would look the same if it were one-story or ten-story building; but the shadow would be much different.

Shape and size. Man-made features are usually bounded by straight or curved lines, while natural features usually have irregular edges. It is important to keep the scale in mind when studying the shapes and sizes. A light square image may represent a building on a 1 : 4,800 print. But the same size of square may represent a cultivated field in a 1 : 20,000 print.

Assignments