Eiffel Tower be used to restrict the publication of tourist photographs of the tower at night, as well as hindering non-profit and semi-commercial publication of images of the illuminated tower. French doctrine and jurisprudence allows pictures incorporating a copyrighted work as long as their presence is incidental or accessory to the subject being represented, a reasoning akin to the "de minimis" rule. Therefore, SETE may be unable to claim copyright on photographs of Paris which happen to include the lit tower. The Eiffel Tower was the world's tallest structure when completed in 1889, a distinction it retained until 1929 when the Chrysler
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