Ever since the early days of civilization in Europe the Alps have been a barrier to the movements of people. The first Alpine tunnel to be constructed was the Mont Cenus tunnel. This great project dates back to 1857. This tunnel is of great technical interest because at that time the only way to get through the rock was to use hand tools. At first the construction advanced very slowly. In fact, if it had continued at the initial pace, it would have taken 5 years to complete the tunnel! However, with compressed air drills and dynamite being introduced, progress was accelerated. Work on the Mont Cenus tunnel started in August 1857 and finished in December 1870.
A) What is the name of the second tunnel cut through the Alps? b) What is the length of the tunnel? c) Why was it dangerous to build tunnels at that time?
The next great and extremely difficult task was the construction of the St. Gotthard tunnel. Italian and Swiss engineers started working on this project in 1872. This tunnel 9.3 miles long was completed 9 years later as compared with 14 years required to make the Mont Cenus tunnel. It should be noted that during the period of construction no less then 800 men lost their lives because of poor ventilation. The only means of ventilating was the compressed air exhausted from the drills. It was so insufficient that the death rate among the workers was extremely great. Needless to say that the ventilation ought to have been much better.
A) What is the longest tunnel cut through the Alps? b) What was done to improve ventilation in the course of tunneling? c) Why was a smaller bore (диаметр тоннеля) adopted?
Both the Mont Cenus and the St. Gotthard tunnels are known to be single tunnels. But when it was decided to bore the Simplon tunnel through the Alps, a different scheme was adopted because geological conditions in this part of the mountains were not simple. The planned length of 12.3 miles was greater than had been done before. According to the project two tunnels were cut, side by side, with transverse galleries connecting them at certain intervals. In this way ventilation was greatly improved and the removal of soil was made much easier. Each tunnel could take only one railway track, so a smaller bore was adopted. Had the tunnel been made the same size as the earlier ones, it might never have been completed. These arrangements made the construction much safer.
TEXT C
Read the text and translate it with a dictionary if necessary. Find out what caused the Tay Bridge and the Tacoma Narrows Bridge disasters and what materials were used for constructing bridges.
BRIDGE CONSTRUCTION
The first bridges were all designed empirically, from the experience gained by previous failures and successes. The history of bridge construction knows many examples when the bridges were built without basic knowledge of Mathematics, which resulted in great tragedies. Engineering failures, although often very costly in life and money, taught extremely valuable lessons.
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You must have heard of Tay Bridge disaster which took place at the end of the last century. The Tay Bridge was designed by Thomas Bouch and opened in June 1878. It was two miles long and spoken about as one of the wonders of the world. But unfortunately principles of aerodynamics which should have been used in designing the bridge were yet unknown. So, the bridge was built without any knowledge about the force a wind can exert on the bridge.
On Sunday afternoon, the 28th of December, 1879, a storm broke out at that place. By evening the wind had reached the greatest force, and the people began to be nervous of what might happen to it in such weather. Some of them went to the end of the bridge to await the arrival of the evening train from Edinburgh. What they saw was a lighted train crossing the bridge. Suddenly the lights disappeared as the engine and coaches fell into the water. All aboard the train were lost and it was difficult to estimate the exact number of people, as some may have been carried out to sea.
The Tacoma Narrows Bridge in the USA, which was the third longest bridge in the world, was opened for traffic in July 1940. Owing to its behavior in wind, it was nicknamed «Galloping Gertie». The deck of the bridge not only swayed sideways but large vertical waves appeared, and the roadway oscillated up and down under the action of quite moderate winds. Drivers of cars reported that when they crossed the bridge vehicles ahead of them completely disappeared from view and reappeared several times, owing to the wavy motion of the roadway.
From the very beginning it was clear that the bridge structure ought to have been strengthened. So, before the bridge was opened several attempts had been made to damp out [уменьшать амплитуду] the oscillations of the main span. But they all were not a success. In November 1940, only four months after the bridge was constructed, it collapsed under the action of wind of only 42 mph, whereas generally bridges are designed to withstand winds of 120 mph.
Early bridges had to be built out of material close at hand. In tropical jungles suspension bridges were made of long bamboo poles. In the places where there were many forests it was wood. In northern areas pier bridges were built out of stone. In Middle Ages people constructed wooden beam type bridges. They were usually built on stone piers or wooden piles. Later, there appeared concrete and metal bridges.
Nowadays some people are experimenting with different unusual materials. One of them is paper. Everyone associated paper with weakness. But paper-makers consider it to be a very strong material. In order to prove it paper-makers built a paper bridge across a narrow canyon in Nevada.
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The bridge covered a span of 32 feet. The designers calculated that it could safely span 80 feet. The structure is ten feet wide and four feet high. It took the engineers only two months to design the bridge, to test and construct it. For testing the engineers chose a truck which weighted 12,000 lb (pounds). This truck drove quite safely across the paper bridge. The engineers are sure that the bridge can take six times the truck load of 12,000 lb. The bridge itself weighs 9,000 lb. So, the structure is light enough to be laid into place by helicopter.
LESSON SEVEN
COMPUTERS
| Words and word combinations to be remembered |
| 1) access –доступ 2) to calculate – вычислять, рассчитывать 3) to click – нажимать, щёлкать 4) compatible –совместимый 5)data – данные, сведения; информация 6) to display– отображать, показывать display– показ; дисплей 7) to download –загружать download – загрузка 8)drawback –недостаток 9) enormous– огромный 10) to erase –стирать 11) error– ошибка 12) to handle –управлять, регулировать 13) hardware – машинное обеспечение компьютера 14) icon – значок 15) keyboard– клавиатура 16) to occupy – занимать 17) to occur – происходить occurrence– происшествие, случай 18) to perform – выполнять 19) to process – обрабатывать 20) to record – записывать record– запись tape recorder –магнитофон 21) to replicate –копировать 22) screen –экран 23) software – программное обеспечение компьютера 24) to solve – решать 25) to sound –звучать sound – звук 26) to spread (spread, spread) –распространяться 27)to store – хранить storage– память, запоминающее устройство 28) to supply (with smth.) – обеспечивать, снабжать (чем-либо) |
Ex.2. Describe the relationship between each of the following words (antonyms, synonyms, neither):
1) to occur/ to happen/ to take place 16) inevitable/ avoidable
2) output/ input 17) to delete/ to destroy/ to eradicate
3) to replicate/ to copy 18) drawback/ disadvantage
4) permanent/ temporary 19) to record/ to erase
5) to store/ to delete 20) to carry out/ to perform/ to execute
6) to provide/ to supply 21) screen/ monitor
7) drawback/ advantage 22) to erase/ to restore
8) to calculate/ to compute/ to count 23) to store/ to keep
9) enormous/ huge/ vast/ gigantic 24) main/ basic
10) to turn on/ to turn off 25) to include/ to comprise
11) particularly/ especially 26) experienced/ inexperienced
12) to install/ to set 27) access/ admittance
13) compatible/ incompatible 28) useful/ useless
14) to display/ to show 29) mistake/ error
15) to record/ to reduce 30) to download/ to reload