Everest

Intoduction

Mount Everest (Tibetan: Qomolangma ; Nepali: Sagarmāthā सगरमाथा; Chinese Zhumulangma Peak simplified Chinese; Limbu Chajamlangma), or Mount Chomolungma, is the world's highest mountain above sea level at 8,848 metres (29,029 ft). It is located in the Himalayas on the Nepal (Sagarmatha Zone)-China (Tibet) border.
In 1856, the Great Trigonometric Survey of British India established the first published height of Everest, then known as Peak XV, at 29,002 ft (8,840 m). In 1865, Everest was given its official English name by the Royal Geographical Society upon recommendation of Andrew Waugh, the British Surveyor General of India at the time, who named it after his predecessor in the post, and former chief, Sir George Everest.[4] Chomolungma had been in common use by Tibetans for centuries, but Waugh was unable to propose an established local name because Nepal and Tibet were closed to foreigners.
The highest mountain in the world attracts many well-experienced mountaineers as well as novice climbers who are willing to pay substantial sums to professional mountain guides to complete a successful climb. The mountain, while not posing substantial technical climbing difficulty on the standard route (other eight-thousanders such as K2 or Nanga Parbat are much more difficult), still has many inherent dangers such as altitude sickness, weather and wind. By the end of the 2008 climbing season, there had been 4,102 ascents to the summit by about 2,700 individuals.[5] Climbers are a significant source of tourist revenue for Nepal, whose government also requires all prospective climbers to obtain an expensive permit, costing up to US $ 25,000 per person.[6] By the end of 2009 Everest had claimed 216 lives,[5] including eight who perished during a 1996 storm high on the mountain. Conditions are so difficult in the death zone (altitudes higher than 8,000 m/26,246 ft) that most corpses have been left where they fell. Some of them are visible from standard climbing routes.
In 1808, the British began the Great Trigonometric Survey of India to determine the location and names of the world's highest mountains. Starting in southern India, the survey teams gradually moved northward using giant 500 kg (1,100 lb) theodolites (each requiring 12 men to carry) to measure heights as accurately as possible.[8]
The British were forced to continue their observations from Terai, a region south of Nepal which is parallel to the Himalayas. Conditions in Terai were difficult owing to torrential rains and malaria — three survey officers died from malaria while two others had to retire owing to failing health.[8]
Nonetheless, in 1847, the British pressed on and began detailed observations of the Himalayan peaks from observation stations up to 240 km (150 mi) away. Weather restricted work to the last three months of the year. In November 1847, Andrew Waugh, the British Surveyor General of India made a number of observations from Sawajpore station located in the eastern end of the Himalayas. At the time, Kangchenjunga was considered the highest peak in the world, and with interest he noted a peak beyond it, some 230 km (140 mi) away. John Armstrong, one of Waugh's officials, also saw the peak from a location further west and called it peak 'b'. Waugh would later write that the observations indicated that peak 'b' was higher than Kangchenjunga, but given the great distance of the observations, closer observations were required for verification. The following year, Waugh sent a survey official back to Terai to make closer observations of peak 'b', but clouds thwarted all attempts.[8]
In 1849, Waugh dispatched James Nicolson to the area. Nicolson was able to make two observations from Jirol, 190 km (120 mi) away. Nicolson then took the largest theodolite and headed east, obtaining over 30 observations from five different locations, with the closest being 174 km (108 mi) away from the peak.[8]
Nicolson retreated to Patna on the Ganges to perform the necessary calculations based on his observations. His raw data gave an average height of 9,200 m (30,200 ft) for peak 'b', but this did not take into account light refraction which distorts heights. The number clearly indicated, however, that peak 'b' was higher than Kangchenjunga. However, Nicolson came down with malaria and was forced to return home, calculations unfinished. Michael Hennessy, one of Waugh's assistants, had begun designating peaks based on roman numerals, with Kangchenjunga named Peak IX, while peak 'b' now became known as Peak XV.[8]
In 1852, stationed at the survey's headquarters in Dehradun, Radhanath Sikdar, an Indian mathematician and surveyor from Bengal, was the first to identify Everest as the world's highest peak, using trigonometric calculations based on Nicolson's measurements.[9] An official announcement that Peak XV was the highest was delayed for several years as the calculations were repeatedly verified. Waugh began work on Nicolson's data in 1854, and along with his staff spent almost two years working on the calculations, having to deal with the problems of light refraction, barometric pressure, and temperature over the vast distances of the observations. Finally, in March 1856 he announced his findings in a letter to his deputy in Kolkata. Kangchenjunga was declared to be 28,156 ft (8,582 m), while Peak XV was given the height of 29,002 ft (8,840 m). Waugh concluded that Peak XV was "most probably the highest in the world".[8] In fact, Peak XV (measured in feet) was calculated to be exactly 29,000 ft (8,839.2 m) high, but was publicly declared to be 29,002 ft (8,839.8 m). The arbitrary addition of 2 ft (61 cm) was to avoid the impression that an exact height of 29,000 feet (8,839.2 m) was nothing more than a rounded estimate.[

The Great Wall

Intoduction
Great wall of China was an ancient gigantic defensive project. It is one of the largest construction projects ever completed.
Great Wall of China is one of the greatest wonders of the world. It winds its way westward over the vast territory of China from the bank of the Yalu River and ends at the foot of snow-covered Qilianshan and Tianshan mountains. It is seldom that we see such a gigantic project in China or elsewhere in the world. The Chinese call it the Wall of 10,000 li. Its size is better seen on a map or from an aerial photograph. According to astronauts who looked back from the moon, of all projects built by man, the Great Wall of China is the most conspicuous seen in space.
The construction of the Great Wall started during the Warring States Period on 7th century B.C, it had a history of more than 2,500 years. Many dukedoms built walls in Central China to protect themselfs and their northern territories. When Qin Shihuang, the first emperor in Chinese history, unified China and established the first centralised feudal state in China, he decided to have the walls linked up and extended.

There were about one million people, one-fifth of China's population at the time, were involved in the project which took more than ten years. Most of the walls we see today were rebuilt during the Ming Dynasty in the 16th century. It extends from Shanhaiguan Pass in the east to Jiayuguan Pass in the west. It is the only construction that the American astronauts could recognize with their naked eyes on their first flight to the Moon.

Those who succeeded in climbing the wall today are often regarded as "Real heroes", from this we should realize the difficulty in climbing the wall, and can imagine how difficult it is to build the Great Wall without modern machinery at that time.

In Beijing, the Great Wall is about 630 km long, 6 sections of the Great Wall have been opened to visitors. There are Badaling Section, Juyongguan Section, Simatai Section, Mutianyu Section, Jinshanling Section and Gubeikou Section.

History

The Chinese were already familiar with the techniques of wall-building by the time of the Spring and Autumn Period, which began around the 8th century BC.^[5][6] During the Warring States Period from the 5th century BC to 221 BC, the states of Qin, Wei, Zhao, Qi, Yan and Zhongshan^[7][8] all constructed extensive fortifications to defend their own borders. Built to withstand the attack of small arms such as swords and spears, these walls were made mostly by stamping earth and gravel between board frames.
Qin Shi Huang conquered all opposing states and unified China in 221 BC, establishing the Qin Dynasty. Intending to impose centralized rule and prevent the resurgence of feudal lords, he ordered the destruction of the wall sections that divided his empire along the former state borders. To protect the empire against intrusions by the Xiongnu people from the north, he ordered the building of a new wall to connect the remaining fortifications along the empire's new northern frontier. Transporting the large quantity of materials required for construction was difficult, so builders always tried to use local resources. Stones from the mountains were used over mountain ranges, while rammed earth was used for construction in the plains. There are no surviving historical records indicating the exact length and course of the Qin Dynasty walls. Most of the ancient walls have eroded away over the centuries, and very few sections remain today. Later, the Han, Sui, Northern and Jin dynasties all repaired, rebuilt, or expanded sections of the Great Wall at great cost to defend themselves against northern invaders. It is estimated that over 1 million workers died building the wall.^[9]
The Great Wall concept was revived again during the Ming Dynasty, following the Ming army's defeat by the Oirats in the Battle of Tumu in 1449. The Ming had failed to gain a clear upper-hand over the Manchurian and Mongolian tribes after successive battles, and the long-drawn conflict was taking a toll on the empire. The Ming adopted a new strategy to keep the nomadic tribes out by constructing walls along the northern border of China. Acknowledging the Mongol control established in the Ordos Desert, the wall followed the desert's southern edge instead of incorporating the bend of the Huang He.

Unlike the earlier Qin fortifications, the Ming construction was stronger and more elaborate due to the use of bricks and stone instead of rammed earth. As Mongol raids continued periodically over the years, the Ming devoted considerable resources to repair and reinforce the walls. Sections near the Ming capital of Beijing were especially strong.^{[citation needed]}
During the 1440s–1460s, the Ming also built a so-called "Liaodong Wall". Similar in function to the Great Wall (whose extension, in a sense, it was), but more basic in construction, the Liaodong Wall enclosed the agricultural heartland of the Liaodong province, protecting it against potential incursions by Jurched-Mongol Oriyanghan from the northwest and the Jianzhou Jurchens from the north. While stones and tiles were used in some parts of the Liaodong Wall, most of it was in fact simply an earth dike with moats on both sides.^[10]
Towards the end of the Ming Dynasty, the Great Wall helped defend the empire against the Manchu invasions that began around 1600. Under the military command of Yuan Chonghuan, the Ming army held off the Manchus at the heavily fortified Shanhaiguan pass, preventing the Manchus from entering the Chinese heartland. The Manchus were finally able to cross the Great Wall in 1644, when the gates at Shanhaiguan were opened by Wu Sangui, a Ming border general who disliked the activities of rulers of the Shun Dynasty. The Manchus quickly seized Beijing, and defeated the newly founded Shun Dynasty and remaining Ming resistance, to establish the Qing Dynasty.