Editing Eiffel Tower (section)

===Material===
[[File:Sous la Tour Eiffel 1.jpg|thumb|The Eiffel Tower from below]]

The [[Puddling (metallurgy)|puddle iron]] (wrought iron) of the Eiffel Tower weighs 7,300 [[tonne]]s,<ref name="Hanser2006">{{cite book|author=David A. Hanser|title=Architecture of France|url=https://books.google.com/books?id=zojzUU976h0C&pg=PA66|year=2006|publisher=Greenwood Publishing Group|isbn=978-0-313-31902-0|page=66}}</ref> and the addition of lifts, shops and antennae have brought the total weight to approximately 10,100&nbsp;tonnes.<ref>{{cite book|title=DK Eyewitness Travel Guide: Europe|url=https://books.google.com/books?id=AiYCSa4U6UYC&pg=PA163|year=2012|publisher=Dorling Kindersley|isbn=978-1-4093-8577-6|page=163}}</ref> As a demonstration of the economy of design, if the 7,300&nbsp;tonnes of metal in the structure were melted down, it would fill the square base, {{convert|125|m|ft}} on each side, to a depth of only {{convert|6.25|cm|in|abbr=on}} assuming the density of the metal to be 7.8&nbsp;tonnes per cubic metre.<ref>Harriss, 1976 p.60.</ref> Additionally, a cubic box surrounding the tower (324&nbsp;m&nbsp;×&nbsp;125&nbsp;m&nbsp;×&nbsp;125&nbsp;m) would contain {{Formatnum:6200}}&nbsp;tonnes of air, weighing almost as much as the iron itself. Depending on the [[Room temperature|ambient temperature]], the top of the tower may shift away from the sun by up to {{convert|18|cm|in|round=0.5|abbr=on}} due to [[thermal expansion]] of the metal on the side facing the sun.<ref>Harriss, 1976 p. 231.</ref>