title: Hydroscope
text: # Hydroscope
  
  A hydroscope is any of several instruments related to water:
  
  * One kind is an instrument for making observations below the surface of water, such as a long tube fitted with various lenses arranged so that objects lying at the bottom can be reflected upon a screen on the deck of the ship that carries it. These are built with a large tire tube that supports the screen and covered by an acrylic dome for protection.
  * Another kind detects subsurface water through nuclear magnetic resonance using the surface nuclear magnetic resonance technique.
  * An instrument (likely a hydrometer) described by Synesius in his Letter 15 to Hypatia, written in 402 AD. There are references to such instruments as early as the fourth century.
  * Another ancient Greek instrument: a water clock or clepsydra.
  
  ## Sources and notes
  
  * ↑ Worthington, David (2003). Dictionary of Environmental Health. London: Spon Press. p. 135. ISBN 0415267242.
  * ↑ Giaccardi, Elisa (2012). Heritage and Social Media: Understanding Heritage in a Participatory Culture. London: Routledge. p. 222. ISBN 9780415616621.
  * ↑ Booth, Charlotte (2017), Hypatia: Mathematician, Philosopher, Myth, London: Fonthill Media, ISBN 978-1-78155-546-0 pp.113-114
  * 1 2 Anderson, Marlow; Katz, Victor; Wilson, Robin (2004). Sherlock Holmes in Babylon: And Other Tales of Mathematical History. The Mathematical Association of America. p. 57. ISBN 0883855461.
  * ↑ "Synesius, Letter 015 - Livius". www.livius.org. Retrieved 2019-02-06.
  * ↑ Waithe, M.E. (1987). Ancient women philosophers, 600 B.C. – 500 A.D. A History of Women Philosophers. Vol. 1. Springer. p. 192.
  * ↑ Forbes, Robert James (1970). A Short History of the Art of Distillation: from the beginnings up to the death of Cellier Blumenthal. Brill. p. 25.
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