Amazing Places: Leaning Tower Of Pisa
The Leaning Tower of Pisa is situated in cathedral of the Italian city of Pisa.
Bonanno Pisano is credited to be the architect of the tower.
The construction of the tower was completed between 1173-1370 (9th August 1173 reported to be the date on which construction of the tower started).
Although intended to stand vertically, the tower began leaning to the southeast soon after the onset of construction in 1173 due to a poorly laid foundation and loose substrate that has allowed the foundation to shift direction. The tower presently leans to the southwest.
The Tower of Pisa was a work of art, performed in three stages over a period of about 177 years.
1198, the establishment of the first bell was documented.
The tower began to sink after construction progressed to the third floor in 1178. This was due to a mere three-meter foundation, set in weak, unstable subsoil indicating that the design was inappropriate right from the start.
Construction was subsequently halted for almost a century, because the Pisans were almost continually engaged in battles with Genoa, Lucca and Florence. This allowed time for the underlying soil to settle. Otherwise, the tower would almost certainly have toppled. In 1198, clocks were temporarily installed on the third floor of the unfinished construction.
On February 27, 1964, the government of Italy requested aid in preventing the tower from toppling. It was, however, considered important to retain the current tilt, due to the vital role that this element played in promoting the tourism industry of Pisa.
On January 7, 1990, after over two decades of work on the subject, the tower was closed to the public. While the tower was closed, the bells were removed to relieve some weight, and cables were cinched around the third level and anchored several hundred meters away.
final solution to prevent the collapse of the tower was to slightly straighten
the tower to a safer angle, by removing 38 cubic meters (50 cu yd) of soil from
underneath the raised end. The tower was straightened by 18 inches (45
centimeters), returning to the exact position that it occupied in 1838. After a
decade of corrective reconstruction and stabilization efforts, the tower was
reopened to the public on December 15, 2001, and has been declared stable for at
least another 300 years.
In May 2008, after the removal of another 70 metric tons (77 short tons) of earth, engineers announced that the Tower had been stabilized such that it had stopped moving for the first time in its history.
tower leans at an angle of 3.97 degrees from the vertical.
The height of the tower is 55.86 m (183.27 ft) from the ground on the lowest side and 56.70 m (186.02 ft) on the highest side. The width of the walls at the base is 4.09 m (13.42 ft) and at the top 2.48 m (8.14 ft).
Its weight is estimated at 14,500 metric tons (16,000 short tons). The tower has 296 or 294 steps; the seventh floor has two fewer steps on the north-facing staircase.
There are seven bells located in the bell Tower, all tuned to musical scales.
Galileo Galilei is said to have dropped two cannon balls of different masses from the tower to demonstrate that their speed of descent was independent of their mass. This is considered an apocryphal tale, and the only source for it comes from Galileo's secretary.
It is famous for leaning 4.4 meters out of line when measured from the seventh story.
It is surprising to note that the inclination of the Tower, measured between 1550 and 1817 by Giorgio Vasari and Cresy and Taylor respectively, was found to have increased by a mere 5 cm. On the other hand, after the conservation work in 1838, the inclination was discovered to have increased by 20 cm.
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