MAIN GEODETIC INSTRUMENTS
Topical vocabulary:
to facilitate | зд. обеспечивать | staff | рейка (с делениями) |
survey | съёмка | rod | рейка, веха |
theodolite | теодолит | bubble | пузырёк |
transit | универсальный теодолит; тахеометр | leveling | нивелирование |
tachymeter | тахеометр | to center | центрировать; выводить на середину пузырёк уровня |
level | нивелир, уровень | ||
cost-effective | рентабельный, оправдывающий затраты | eye piece | окуляр |
to pivot [‘pivәt] | вращаться | reading | показание измерительных приборов |
to measure | измерять | EDM (electronic distance measurement) | электронные средства измерения расстояния |
axis | ось | technique | метод, способ выполнения |
sight | визирование; визировать; наблюдать | ground point | точка местности |
line of sight | линия визирования | sophisticated | сложный, усложненный; современный |
superior optics | высококлассная оптика | cross hairs | крест (сетка) нитей |
stadia [‘steidiә] hairs | горизонтальные параллельные нити (в теодолите) | tripod | штатив, тренога |
precision, accuracy | точность |
Text
(1) Geodetic, topographic, hydrographic and cadastral surveys are carried out by the application of electronics and computer sciences. At the same time, superior optics and more refined instruments, in general, have facilitated the precision of observations and accuracies of the end product.
(2) It is surprising that classical instruments are still found in many fields of surveying. Geodesists have following reasons for that:
1. Classical instruments can be used to perform many new surveying tasks without difficulties.
2. Good performance at a reasonable price.
3. They are ready for use at any time independent of the battery charge.
4. Even under extreme climatic conditions they function without errors.
(3) Though different modern techniques are acceptable for measuring angles usually special instrument called theodolite is used in surveying for this purpose. It can assure the accuracy required in the framework needed for precise mapping. The theodolite consists of a telescope pivoted around horizontal and vertical axes so that it can measure both horizontal and vertical angles. These angles are read from circles graduated in degrees and smaller intervals of 10 or 20 minutes.
(4) In surveying for engineering projects, more sophisticated instruments are employed to maximize accuracy. For example, distances may be measured by EDM (electronic distance measurement) or by tachymetry, a geometric technique in which the vertical distance on a graduated vertical staff, seen between two stadia hairs in the theodolite eyepiece, is a measure of the horizontal distance between the theodolite and the staff – usually 100 times the difference between the two readings.
(5) Modern surveying instruments combine a theodolite, EDM equipment, and a computer that records all the observations and calculates the height differences obtained by measuring vertical angles.
Heights of surface features above sea level are determined by leveling. The level has been used by surveyor for centuries. It consists of horizontal telescope fitted with cross hairs, rotating around a vertical axis on a tripod, with a very sensitive spirit level fixed to it; the instrument is adjusted until the bubble is exactly centered. It is used for measuring height differences over long horizontal distances.
Practical work
MAIN GEODETIC INSTRUMENTS
I. Complete the sentences:
1. … is used for measuring angles.
2. … is pivoted around horizontal and vertical axes.
3. Heights of surface are determined by ….
4.... … consists of horizontal telescope on a tripod.
5. The instrument is adjusted until the … … is exactly centered.
II. Find English equivalents of the following:
1) топосъёмка;
2) гидрографическая съёмка;
3) кадастровая съёмка;
4) высококлассная оптика;
5) точность наблюдений;
6) разница между двумя показаниями;
7) при экстремальных климатических условиях;
8) гарантировать необходимую точность;
9) измерять горизонтальные и вертикальные углы;
10) разумная цена.
III. Find these sentences in the text and insert missing prepositions:
1. Even …… extreme climatic conditions they function without errors.
2. The theodolite consists …… a telescope pivoted …… horizontal and vertical axes.
3. They are ready for use …… any time independent …… the battery charge.
4. Surveys are carried …… ……. the application of electronics and computer sciences.
5. Good performance ……. a reasonable price.
IV. Answer the questions:
1. What helps to produce surveys?
2. Why is classical theodolite still used?
3. What does a theodolite consist of?
4. What do modern surveying instruments combine?
5. What is tachymetry?
6. What is leveling used for?
7. What does a level consist of?
V. Find the English equivalents for these sentences in the text:
1. Съёмка осуществляется с применением электронных приборов и компьютера.
2. Удивительно, что классические инструменты всё ещё применяются для проведения съёмки.
3. Эти инструменты не зависят от зарядки аккумулятора.
4. Для измерения углов обычно используется теодолит.
5. Сложные инструменты используются для достижения максимальной точности.
6. Нивелир снабжён чувствительным спиртовым уровнем.
Estimation Criteria:
28-33 points – “ excellent” (5)
22-27 points – “good” (4)
16-21 points –“satisfactory” (3)