Vertical caving terminology and methods > Personal SRT gear
A tether connecting the top jammer, lower jammer or knee jammer to the D-ring. Serves as a safety connection to the rope if the chest jammer, lower jammer or chest roller is disconnected (depending on which prusiking system is being used). Sometimes made from the same piece of rope as the footloop. Sometimes connected part way down the footloop instead of being connected directly to the top jammer, common with the Plummer system. Sometimes a carabiner is added to the end, allowing it to be used as a third cows tail. Sometimes the cows tails are used as safety cords, but that then makes it impossible to use them safely as actual cows tails, so that approach only tends to be used in places where indestructible rope technique is used. It is also used in some parts of France, leaving only one cows tail to use as an actual cows tail. Not to be confused with bungee cord, which can also be called shock cord.
The idea of a safety connection to a first ascender was first devised by German inventor Ed. von Mengden in 1878 for use with his ascenders with the hands and feet system. In 1920, French exterior decorator Antoine Joseph Marius "Paul Cans" Barthelemy created two safety cords between an ascender and a chest harness and sit harness, for his development of rope walking. This idea was repeated by French mountaineer E. Gérard in 1928 for use with the Gérard Alpine technique, connecting a prusik loop to a chest harness. The use of a safe connection to two ascenders at once happened by chance as a result of the development of the fourth sling variation of the frog system, by American caver Dan Bloxsom in 1955. The idea of adding a safety cord from an ascender to either the chest harness or a sit harness had re-emerged in the USA by 1965 when the Wisconsin system development started by Dick Boyd, Carl Poster and Bob Olmstead. The idea of using an intentional safety cord to connect to a second ascender to allow a redundant safety system was developed in America by cavers Charles Gibbs and Cleveland Grotto members including Warwick Doll and Lee Watson, some time around 1966, but may have existed as an idea before then. Robert "Bob" Thrun describes using them with prusik loops in Prusiking, 1973. A safety cord was used to a second ascender in the frog system and the UBSS system variation of the Jumar system by the University of Bristol Spelaeological Society during an expedition to Slovenia in 1972. The idea of a safety cord being used to connect to a second ascender was then adoped into the re-developed frog system by French cavers Jean Claude Dobrilla and Georges Marbach, who wrote about it in the first edition of Techniques de la Spéléologie Alpine in 1973. At that time, it was probably adopted into most other prusiking systems as well.
This history section only covers safety cords. This article also has a detailed history of many of the other devices and techniques that are used for vertical caving.
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