Petřín Lookout Tower of the Eiffel Tower. In contrast to the Eiffel Tower, Petřínská rozhledna has an octagonal, not square, cross-section. Further, it does not stand, as does the Eiffel Tower, on four columns of lattice steel. The whole area under its legs is covered with the entrance hall. A similarity between the Eiffel Tower and Petřínská rozhledna is the design of the lowest cross beams in the form of round bones. In 1889, members of the Club of Czech Tourists visited the world exposition in Paris and were inspired by the Eiffel Tower. They collected a sufficient amount of money and in
Eiffel Tower gaps in the latticework. In the years since it was completed, engineers have put forward various mathematical hypotheses in an attempt to explain the success of the design. The most recent, devised in 2004 after letters sent by Eiffel to the French Society of Civil Engineers in 1885 were translated into English, is described as a non-linear integral equation based on counteracting the wind pressure on any point of the tower with the tension between the construction elements at that point. The Eiffel Tower sways by up to 9 centimetres (3.5 in) in the wind. When originally built, the first