EIFFEL

TOWER  . Erected for the exposition of 1889, the Eiffel Tower, in the Champ de Mars, Paris, is by far the highest artificial structure in the world, and its height of 300 metres (984 ft.) surpasses that of the obelisk at Washington by 429 ft., and that of St Paul's cathedral by 58o ft . Its framework is composed essentially of four uprights, which rise from the corners of a square measuring '<o metres on the side; thus the area it covers at its base is nearly 21 acres . These uprights are supported on huge piers of masonry and concrete, the foundations for which were carried down, by the aid of iron caissons and compressed air, to a depth of about 15 metres on the side next the Seine, and about 9 metres on the other side . At first they curve upwards at an angle of 540; then they gradually become straighter, until they unite in a single shaft rather more than half-way up . The first platform, at a height of 57 metres, has an area of 586o sq. yds., and is reached either by staircases or lifts . The next, accessible by lifts only, is 115 metres up, and has an area of 32 sq. yds; while the third, at 276, supports a pavilion capable of holding 800 persons . Nearly 25 metres higher up still is the lantern, with a gallery 5 metres in diameter .. The work of building this structure, which is mainly composed of iron lattice-work, was begun on the 28th of January 1887, and the full height was reached on the 13th of March 1889 . Besides being one of the sights of Paris, to which visitors resort in order to enjoy the extensive view that can be had from its higher galleries on a clear day, the tower is used to some extent for scientific and semi-scientific purposes; thus meteorological observations are carried on . The engineer under whose direction the tower was constructed was Alexandre Gustave Eiffel (born at Dijon on the 15th of December 1832), who had already had a wide experience in the construction of large metal bridges, and who designed the huge sluices for the Panama Canal, when it was under the French company .