The Medicine Chest

Items

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  Diving the Tacoma Narrows Bridge

  "All that debris still remains under the bridge for the most part, and it has become a dive site. It is a very difficult dive site to get to because of the swiftly moving water and the very short period of slack time. ​Nature in this area has just a tremendous ability to take over. You have a man-made structure like the Tacoma Narrow Bridge that collapsed into the water. Very quickly, the ocean took it over and made it part of the habitat". Extract from the voiceover of trailer for 700 Feet Down (a documentary about the Tacoma Narrows Bridge told through witnesses of the bridge’s 1940 demise as well as intrepid divers exploring a reef of wreckage, ultimately reflecting on how history influences the present)
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  Resonance

  Image from page 137 of the 'Curiosity CLXXV' catalogue, describing resonance and its application in MRI technology.
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  Devils Bridge sketched by Lister

  'Devils Bridge' sketched by Lister on his travels through Europe showing a bridge crossing the Gotthard Pass, northern approach, Switzerland. ​The term 'devil's bridge' is applied to many ancient bridges found primarily in Europe. These were stone or masonry arch bridges and, because they represented a significant technological achievement in ancient architecture, were objects of fascination and stories. The most popular of these featured the Devil, either as the builder of the bridge (relating to the precariousness or impossibility of such a bridge to last or exist in the first place) or as a pact-maker (sharing the necessary knowledge to build the bridge, usually in exchange for the communities souls). The legend attached to the bridge sketched by Lister is of the latter, and was related by Johann Jakob Scheuchzer in 1716. According to Scheuchzer, the people of Uri recruited the Devil for the difficult task of building the bridge. In return for his expertise, the Devil requested the soul of the first thing to pass the bridge. To trick the Devil, the people of Uri sent across a dog by throwing a piece of bread, and the dog was promptly torn to pieces by the Devil. Reference: Scheuchzer, J. , 1747 [1716]. Naturgeschichte des Schweitzerlandes. Vol. 2: 94.
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  Resonance

  Demonstration of sympathetic vibration using the optical (flame) microphone
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  The Tacoma Narrows Bridge

  The old Tacoma Narrows bridge was named Galloping Gertie because it vibrated rather strongly whenever there was a little wind due to resonance, the property which most objects have, of vibrating more strongly when exposed to an external force which is itself vibrating at the object's natural frequency. Crossing Gertie was actually quite a popular thing to do, similar to riding a roller-coaster. On November 7, 1940, things changed for the worse however. It was a day of rather high winds which caused Gertie to take on a 30-hertz transverse vibration with an amplitude of 1½ feet. This developed into a twisting motion of about 14 hertz, which then tore the bridge in two. The only victim of the disaster was a three-legged Cocker Spaniel, Tubby, left in the back seat of a lone car abandoned on the bridge.