Vodeni časovnik

Dva vodena sata iz stare Grčke

Stari Persijski časovnik

Rekonstrukcija upravljanja peščanim satom, Iran

Model u pravoj veličini Su Songove Astronomske satne kule.

Vodeni časovnik iz doba Antičkog Rima, postavka Narodnog muzeja u Požarevcu

Vodeni sat ili klepsidra (grčki: κλέπτειν kleptein, 'ukrasti'; ὕδωρ hudor, 'voda') je naprava za merenje vremena uz pomoć protoka vode iz posude, obično kroz uzani otvor. Iako nikad nisu postigli takav stepen tačnosti prema savremenim standardima merenja vremena, vodeni sat je bio najtačniji instrument u širokoj upotrebi milenijumima, sve dok nije zamenjen mnogo preciznijim satovima s klatnom u 17. veku.

Prema istraživaču Džimu Macjejevskom, vodeni satovi su bili prvi merači vremena koje je stvorilo čovečanstvo. Iako ne postoji saglasnost oko toga gde i kada je prvi vodeni sat napravljen, zna se da su vodeni satovi postojali na području Mesopotamije u (Sumeru, vavilonu, Asiriji), i u Indiji i Kini. Smatra se da je nastao između 3000. p. n. e. - 1500. p. n. e., a možda i ranije. Neki nacrti vodenih satova razvili su se nezavisno, a neka znanja su prenošena razvojem trgovine. U najranijim vremenima, vodeni satovi su korišćeni za potrebe astronomije i astrologije. Ovi rani vodeni satovi su podešavani pomoću sunčanog sata. Kroz vekove, vodeni satovi su korišćeni za merenje dužine govora advokata, za rad prostitutki, kao noćni satovi stražara, za besede i službe u crkvama.

Jedno od najranijih otkrića vodenog sata bilo je u grobnici egipatskog faraona Amenhotepa I (1525. – 1504. p. n. e.). Ovaj sat je u čast Amenhotepa I napravio Amenemhet, velikodostojnik 18. dinastije. Grci su ih kasnije nazvali klepsidre ("kradljivci vode"), koji su počeli da ih upotrebljavaju od 325. p. n. e., bile su to kamene posude sa strmim stranama koje su omogućavale da voda ujednačeno kaplje iz male rupe pri dnu. Druge klepsidre su bile cilindrične ili kupaste posude koje su se lagano i ujednačeno punile vodom. Oznake na unutrašnjosti posude merile su „sate“. Ovi satovi su korišćeni da mere sate noću, ali su korišćeni i danju. Druga verzija se sastojala od metalnog pehara s rupom na dnu; kada bi se postavio u veću posudu s vodom pehar bi se punio i tonuo u određenom vremenu. Ovakvi vodeni satovi koristili su se u severnoj Africi u 20. veku.

Mnogo razvijeniji i impresivniji mehanizovani vodeni satovi razvili su između 270. p. n. e. i 500. Grci (Ktesibije, heroj Aleksandrije, Arhimed) i rimski časovničari i astronomi. Oni su dodali delove koji su uz pomoć regulisanja pritiska omogućavali konstantan protok vode, a merenje vremena bilo je živopisnije. Neki vodeni satovi su zvonili ili koristili gongove; drugi su otvarali vrata i prozore s malim figurama ljudi, ili su pokretali pokazivače, brojčanike i astrološke modele svemira.

Krli astronom, Andronik iz Kira, nadgledao je izgradnju svog horologa, koji je danas poznat kao Kula vetrova, a nalazio se na atinskom trgu (agora) u prvoj polovini 1. veka p. n. e. Ova osmougaona kula pokazivala je učenjacima i trgovcima i sunčano mehaničko vreme. Imala je mehanizovanu klepsidru koja je radila 24 sata i pokazivače osam vetrova, po čemu je kula dobila ime, a pokazivala je i godišnja doba i astrološke datume i periode. Rimljani su takođe razvili mehaničke klepsidre, mada je njihova složenost pokazala mali napredak u odnosu na jednostavnije metode određivanja vremena.

U istočnoj Aziji, vodeni satovi su bili od velike važnosti u astronomiji i astrologiji. Kineske klepsidre iz 3. veka pokretale su različite mehanizme koje su ilustrovale astronomske fenomene. Jednu od najrazvijenijih satnih kula izgradio je Su Song (蘇頌) sa saradnicima 1088. Su Songov mehanizam imao je uspinjač koji je pokretala voda koji je otkriven oko 725. Su Songova sahat kula, preko 30 stopa visoka, imala je bronzani sferični astrolab (model nebeske sfere) koji je služio za posmatranja, automatski rotirajući nebeski svod i pet prednjih ploča s vratima na kojima su se pojavljivali patuljci koji su udarali u zvona ili gongove i držali table koje su pokazivale sate ili drugo vreme. Od najranijih vremena, kineske sprave za merenje vremena prešle su i na korejsko poluostrvo.

U Koreji, merenje vremena bilo je istovremeno i kraljevska dužnost i povlastica od perioda Tri kraljevstva (oko 37. p. n. e.) naovamo. Čang Jongsil, glavni inženjer u vreme Čoson dinastije Dynasty je 1434. konstruisao „Čagjongnu“ (vodeni sat s odbrojavanjem za kralja Sedžonga. Ovaj sat je odbrojavao časove pomoću mehanizma s čekrcima, pomoću koga su tri drvene figure otkucavale časove. „Čagjongnu“ je bio potpuno automatizovana naprava kojoj nije bila potrebna pomoć „čoveka petla“ da ga podešava. Od 554. vodeni sat se proširio iz Koreje na Japan. Vodeni satovi su se koristili i unapređivali širom Azije si 15. veka.

Danas ima malo vodenih satova. Bernard Giton je 1979. godine počeo da pravi svoje vodene satove, koji su moderan pristup u izradi vodenih satova. Njegov jedinstveni dizajn se može naći na nekoliko mesta u Sjedinjenim Državama i preko 30 lokacija širom sveta. Postoje i drugi moderni nacrti vodenih satova, ali uopšteno govoreći, veština izrade vodenih satova je danas izgubljena.

Literatura

Pregled vodenih satova i drugih vremenskih instrumenata

• Barnett, Jo Ellen. Time's Pendulum: From Sundials to Atomic Clocks, the Fascinating History of Timekeeping and How Our Discoveries Changed the World. Plenum Press, NY. 1998. ISBN 978-0-15-600649-1.
• Bruton, Eric. The History of Clocks and Watches. 1979. ISBN 978-0-8478-0261-6.
• Cowan, Harrison J. (1958). Time and Its Measurement: From the stone age to the nuclear age. Ohio: The World Publishing Company. Bibcode:1958tmfs.book.....C. 
• Dohrn-van Rossum, Gerhard (1996). History of the Hour: Clocks and Modern Temporal Orders. Trans. Thomas Dunlap. The University of Chicago Press. ISBN 978-0-226-15510-4. OCLC 33440282. 
• K. Higgins, D. Miner, C.N. Smith, D.B. Sullivan (2004), A Walk Through Time (version 1.2.1). [Online] Available: http://physics.nist.gov/time [2005, December 8]. National Institute of Standards and Technology, Gaithersburg, MD.
• Jespersen, James and Fitz-Randolph, Jane. "From Sundials to Atomic Clocks: Understanding Time and Frequency." Second Revised Edition. 1999. ISBN 978-0-486-40913-9.
• „Towards a History from Antiquity to the Renaissance of Sundials and Other Instruments for Reckoning Time by the Sun and Stars H<SCP>ESTER</SCP> H<SCP>IGTON</SCP>, Sundials—An Illustrated History of Portable Dials . London: Philip Wilson, 2001. Reviewed by D<SCP>AVID</SCP> A. K<SCP>ING</SCP>, Institute for the History of Science, Johann Wolfgang Goethe University, D‐60054 Frankfurt am Main, Germany H<SCP>ESTER</SCP> H<SCP>IGTON</SCP>, with contributions from S<SCP>ILKE</SCP> A<SCP>CKERMANN</SCP>, R<SCP>ICHARD</SCP> D<SCP>UNN</SCP>, K<SCP>IYOSHI</SCP> T<SCP>AKADA</SCP> and A<SCP>NTHONY</SCP> T<SCP>URNER</SCP>, Sundials at Greenwich—A Catalogue of the Sundials, Horary Quadrants and Nocturnals in the National Maritime Museum, Greenwich . Oxford: Oxford University Press, and Greenwich: National Maritime Museum, 2002”. Annals of Science. 61 (3): 375—388. 2004. doi:10.1080/00033790310001642795. .
• Landes, D. Revolution in Time. Harvard University Press (1983).
• McNown, J.S. "When Time Flowed: The Story of the Clepsydra." La Houille Blanche, 5, 1976, 347-353. ISSN 0018-6368
• Milham, Willis I. Time & Timekeepers including The History, Construction, Care, and Accuracy of Clocks and Watches. The Macmillan Company, NY 1945.
• Rees, Abraham. "Rees's Clocks, Watches, and Chronometers 1819-20." Charles E. Tuttle Company, Inc. 1970.
• Richards, E.G (1998). Mapping Time: The Calendar and Its History. Oxford University. .
• Toulmin, Stephen; Goodhead, J. (1999). The Discovery of Time. University of Chicago Press. ISBN 978-0-226-80842-0. 
• Turner, Anthony J. (1984). The Time Museum. I: Time Measuring Instruments; Part 3: Water-clocks, Sand-glasses, Fire-clocks. Rockford, IL: The Museum. ISBN 978-0-912947-01-3. OCLC 159866762. 

Арапски и исламски водени сатови

• Hill, Donald Routledge (ed. & trans.) (1976). Archimedes "On the Construction of Water-Clocks" Turner & Devereux, Paris.
• Hill, D.R. (1981). „Arabic Water - Clocks”. Syria: University of Aleppo. 
• al-Hassan, Ahmad Y.; Hill, Donald R. (1986). Islamic Technology: An Illustrated History. Cambridge University Press. ISBN 978-0-521-26333-7. OCLC 13332728. 
• Hill, Donald Routledge. "Studies in Medieval Islamic Technology: From Philo to Al-Jazari - from Alexandria to Diyar Bakr." (Collected Studies Series, 555)
• King, D. Mikat. "Astronomical Timekeeping." The Encyclopaedia of Islam. 7, Brill, (1990) Reprinted as Chapter V in King, D. "Astronomy in the Service of Islam Variorum." (1993)

Вавилонски водени сатови

• Englund, R.K. "Administrative Timekeeping in Ancient Mesopotamia." Journal of the Economic and Social History of the Orient, V. XXXI, 31 (1988) 121-185.
• Fermor, John, & Steele, John M. "The design of Babylonian waterclocks: Astronomical and experimental evidence." Centaurus. International Journal of the History of Mathematics, Science, and Technology. Vol. 42 Issue 3, pp. 210–222. July 2000. Blackwell Publishing.
• Høyrup, J., "A Note on Waterclocks and the Authority of Texts." Archiv für Orientforschung, 44/45 (1997/98), 192-194 (*).
• Michel-Nozières, C. "Second Millennium Babylonian Water Clocks: a physical study." Centaurus, Vol. 42, Issue 3, pp. 180–209. July 2000.
• Neugebauer, Otto (1947). „Studies in Ancient Astronomy. VIII. The Water Clock in Babylonian Astronomy”. Isis. 37 (1/2): 37—43. PMID 20247883. S2CID 120229480. doi:10.1086/347965. . Reprinted in Neugebauer (1983), pp. 239–245 (*).
• Price, Derek deSolla. Science Since Babylon. Yale University Press, New Haven 1976.
• Teresi, Dick. "Lost Discoveries: The Ancient Roots of Modern Science - from the Babylonians to the Maya." Simon & Schuster, NY 2002.
• van der Waerden, Bartel Leendert, "Babylonian Astronomy: III. The Earliest Astronomical Computations." Journal of Near Eastern Studies, 10 (1951), 20-34 JSTOR link.

Кинески водени сатови

• Lorch, Richard P. "Al-Khazini's Balance-clock and the Chinese Steelyard Clepsydra." Archives Internationales d'Histoire des Sciences, June 1981, 31: 183-189.
• Needham, J.; Ling, W; de Solla Price, D.J. (1986). Heavenly Clockwork: The Great Astronomical Clocks of Medieval China (2nd изд.). CUP Archive. ISBN 978-0-521-32276-8. .
• Needham, Joseph (1995). Science & Civilisation in China. III: Mathematics and the Sciences of the Heavens and the Earth. Cambridge University Press. ISBN 978-0-521-05801-8. OCLC 153247126. 
• Needham, Joseph (2000). Science & Civilisation in China. IV:2: Mechanical Engineering. Cambridge University Press. ISBN 978-0-521-05803-2. OCLC 153247141. 
• Quan, He Jun. "Research on scale and precision of the water clock in ancient China." History of Oriental Astronomy, pp. 57–61. (Proceedings of the International Astronomical Union Colloquium No. 91 held in New Delhi, November 13–16, 1985). G. Swarup, A. K. Bag and K. S. Shukla, ур. (1987). History of Oriental Astrony. Cambridge: Cambridge University Press. стр. 57–61. ISBN 978-0-521-34659-7. .
• Walsh, Jennifer Robin. "Ancient Chinese Astronomical Technologies." American Physical Society, Northwest Section. May, 2004. Meeting, 21–22 May 2004. Pullman, WA.

Египатски водени сатови

• Clagett, Marshall (1995). Ancient Egyptian Science. II: Calendars, Clocks, and Astronomy. стр. 457—462. ISBN 978-0-87169-214-6. 
• Cotterell, B., Dickson, F.P., and Kamminga, J. "Ancient Egyptian Water-clocks: A Reappraisal." Journal of Archaeological Science. Vol. 13, pp. 31–50. 1986.
• Cotterell, Brian and Kamminga, Johan. "Mechanics of pre-industrial technology." Cambridge University Press, Cambridge. 1990.
• Fermor, John (1997). „Timing the sun in Egypt and Mesopotamia”. Vistas in Astronomy. 41 (1): 157—167. Bibcode:1997VA.....41..157F. doi:10.1016/S0083-6656(96)00069-4. .
• Neugebauer, Otto & Parker, Richard A. "Egyptian Astronomical Texts: Iii. Decans, Planets, Constellations, and Zodiacs."
• Pogo, Alexander. "Egyptian water clocks", Isis, vol. 25, pp. 403–425, 1936. Reprinted in Philosophers and Machines, O. Mayr, editor, Science History Publications, 1976. ISSN 0021-1753
• Sloley, R.W., "Ancient Clepsydrae", Ancient Egypt, 1924, pp. 43–50.
• Sloley, R.W., "Primitive methods of measuring time", JEA 17, 1931, pp. 174–176.

Европски водени сатови

• Bedini, S.A. . (1962). „The Compartmented Cylindrical Clepsydra.”. Technology and Culture. 3 (2): 115—141. JSTOR 3101437. S2CID 112844914. doi:10.2307/3101437. . ISSN 0040-165X
• Drover, C.B. "A Medieval Monastic Water Clock", Antiquarian Horology, Vol. I, No. 5 (1954), pp. 54–58.
• Hill, Donald Routledge. "A History of Engineering in Classical and Medieval Times." La Salle, Ill., Open Court Pub. 1996. ISBN 978-0-415-15291-4.
• Hill, D.R. "The Toledo Water-Clocks of c.1075." History of Technology, vol.16, 1994, pp. 62–71
• Scattergood, John. "Writing the clock: the reconstruction of time in the late Middle Ages." European Review, Issue 4 (Oct, 2003), 11: pp. 453–474 Cambridge University Press (School of English, Trinity College, Dublin 2, Ireland. jscatter@tcd.ie)

Grčki i aleksandrijski vodeni satovi

• Hill, D.R. (ed. & trans.) (1976). Archimedes "On the Construction of Water-Clocks" Turner & Devereux, Paris.
• Lepschy, Antonio M. (1992). „Feedback Control in Ancient Water and Mechanical Clocks.”. IEEE Transactions on Education. 35 (1): 3. Bibcode:1992ITEdu..35....3L. doi:10.1109/13.123411. 
• Lewis, Michael (2000). „Theoretical Hydraulics, Automata, and Water Clocks”. Ur.: Wikander, Örjan. Handbook of Ancient Water Technology. Technology and Change in History. Leiden. 
• Noble, J.V. & de Solla Price, D. J. "The Water clock in the Tower of the Winds." American Journal of Archaeology, 72, 1968, pp. 345–355.
• Woodcroft, Bennet (translator). "The Pneumatics of Hero of Alexandria." London, Taylor Walton and Maberly, 1851.
• Vitruvius, P., The Ten Books on Architecture. (M.H. Morgan, translator) New York: Dover Publications, Inc., 1960.

Indijski vodeni satovi

• Achar, N. "On the Vedic origin of the ancient mathematical astronomy of India." Journal of Studies on Ancient India, vol 1, 95-108, 1998.
• Fleet, J. F., "The ancient Indian water clock." Journal of the Royal Asiatic Society, 213-230, 1915.
• Kumar, Narendra (2004). Science in Ancient India. Anmol Publications. ISBN 978-81-261-2056-7. .
• Pingree, D. "The Mesopotamian origin of early Indian mathematical astronomy." Journal for the History of Astronomy, vol. 4, 1-12, 1973.
• Pingree, D. "The recovery of early Greek astronomy from India." Journal for the History of Astronomy, vol 7, 109-123, 1976.

Japanski vodeni satovi

• Kiyoyasu, Maruyma. "Hoken shakai to gijutsu - wadokei ni shuyaku sareta hoken gijutsu." Kagakushi kenkyu, September 1954, 31:16-22.

Korejski vodeni satovi

• Hahn, Young-Ho and Nam, Moon-Hyon. (1997). „Reconstruction of the Armillary Spheres of Mid-Chosun: The Armillary Clocks of Yi Minchol.”. Hanguk Kwahaksa Hakhoeji (Journal of the Korean History of Science Society). 19 (1): 3—19. CS1 održavanje: Višestruka imena: spisak autora (veza). (in Korean)
• Hahn, Young-Ho, et al. "Astronomical Clocks of Chosun Dynasty: King Sejong's Heumgyonggaknu. Kisulgwa Yoksa (Journal of the Korean Society for the History of Technology and Industry). . 1 (1). 2000: 99—140.  . (in Korean).
• Hong, Sungook (jul 1998). „Book Review: Korean Water-Clocks: "Chagyongnu", the Striking Clepsydra, and the History of Control and Instrumentation Engineering”. Technology and Culture. 39 (3): 553—555. CS1 održavanje: Format datuma (veza)
• Nam, Moon-Hyon (1990). „Chagyongnu: The Automatic Striking Water clock.”. Korea Journal. 30 (7): 9—21. .
• Nam, Moon-Hyon. Korean Water Clocks: Jagyongnu, The Striking Clepsydra and The History of Control and Instrumentation Engineering. . Seoul: Konkuk University Press. 1995. . (in Korean)
• Nam, Moon-Hyon. On the BORUGAKGI of Kim Don—Principles and Structures of JAYEONGNU. Hanguksa Yeongu (Studies on Korean History). . 101 (1998): 75—114.  (in Korean)
• Nam, Moon-Hyon. Jang Yeong-Shil and Jagyeongnu - Reconstruction of Time Measuring History of Choseon Period. . Seoul National University Press. 2002. . (in Korean)
• Nam, Moon-Hyon and Jeon San-Woon. "Timekeeping Systems of Early Choson Dynasty." Proceedings of First International Conference on Oriental Astronomy, From Guo Shoujing to King Sejong, Seoul, October 6–11, 1993. . Seoul: Yonsei University Press. 1997. pp. 305–324. .
• Needham, Joseph, Major, John S., & Gwei-Djen, Lu. "Hall of Heavenly Records: Korean Astronomical Instruments and Clocks, 1380-1780." Cambridge [Cambridgeshire] ; New York. The Hall of Heavenly Records: Korean Astronomical Instruments and Clocks, 1380-1780. Cambridge University Press. 1986. ISBN 978-0-521-30368-2. 
• Hyeonjong Shillock (Veritable Records of King Hyeonjong), 1669
• Jungjong Shillok (Veritable Records of King Jungjong), 1536.
• Sejong Shillock (Veritable Records of King Sejong), Chapter. 65, AD 1434 and Chapter. 80, AD 1438.

Mezopotamijski vodeni satovi

• Brown, David R., Fermor, John, & Walker, Christopher B.F., "The Water Clock in Mesopotamia." Archiv für Orientforschung, 46/47 (1999/2000)
• Chadwick, R. "The Origins of Astronomy and Astrology in Mesopotamia." Archaeoastronomy. BULL. CTR ARCH. V. 7:1-4, P. 89, 1984. KNUDSEN Bibliographic Code: 1984BuCAr...7...89C
• Fermor, John (1997). „Timing the sun in Egypt and Mesopotamia”. Vistas in Astronomy. 41 (1): 157—167. Bibcode:1997VA.....41..157F. doi:10.1016/S0083-6656(96)00069-4. .
• Walker, Christopher and Britton, John. "Astronomy and Astrology in Mesopotamia." BMP, 1996 (especially pp. 42–67)

Ruski drevni vodeni satovi

• Vodolazhskaya, Larisa N.; Usachuk, Anatoliy N.; Nevsky, Mikhail Yu. [http://aaatec.org/documents/article/vl6.pdf „Clepsydra of the Bronze Age from the Central Donbass” (PDF). Archaeoastronomy and Ancient Technologies. 3 (1): 65—87. 2015. .]

Današnji vodeni satovi

• Gitton, Bernard. "Time, like an everflowing stream." Trans. Mlle. Annie Chadeyron. Ed. Anthony Randall. Horological Journal 131.12 (June 1989): 18-20.
• Taylor, Robert. "Taiwan's Biggest Cuckoo Clock?: Recreating an Astronomical Timepiece". Sinorama Magazine. 3-15-2006
• Xuan, Gao. "Principle Research and Reconstruction Experiment of the Astronomical Clock Tower in Ancient China." Proceedings of the 11th World Congress in Mechanism and machine Science. August 18–21, 2003. Tianjin, China.

Ostale teme o vodenim satovima i srodnim materijalima

• Goodenow, Jennifer; Orr, Richard; Ross, David (2007), Mathematical Models of Water Clocks (PDF), Rochester Institute of Technology 
• Landels, John G. . (1979). „Water-Clocks and Time Measurement in Classical Antiquity.”. Endeavour. 3 (1): 32—37. doi:10.1016/0160-9327(79)90007-3. . ISSN 0160-9327
• Mills, A. A. (1982). „Newton's Water Clocks and the Fluid Mechanics of Clepsydrae”. Notes and Records of the Royal Society of London: 35—61. JSTOR 531476. S2CID 145355791. doi:10.1098/rsnr.1982.0004.  ISSN 0035-9149
• Neugebauer, Otto (1969) [1957]. The Exact Sciences in Antiquity (2 izd.). Dover Publications. ISBN 978-0-486-22332-2. 
• Sarma, S.R., "Setting up the Water Clock for Telling the Time of Marriage." in Studies in the History of the Exact Sciences in Honour of David Pingree, éd. Ch. Burnett, J.P. Hogendijk, K. Plofker, M. Yano, Leiden-Boston, 2004, pp. 302–330.
• Snell, Daniel (januar 1997). Life in the Ancient Near East, 3100-332 B.C.E. Yale University Press. ISBN 978-0-300-07666-0. CS1 održavanje: Format datuma (veza).

Neengleski resursi

• Bilfinger, Gustav, Die babylonische Doppelstunde: Eine chronologische Untersuchung (Wildt, Stuttgart, 1888).
• Borchardt, Ludwig. 1920. "Die Altägyptische Zeitmessung." (Old Egyptian time measurement). Berlin/Leipzig.
• Daressy, G., "Deux clepsydres antiques", BIE, serie 5, 9, 1915, pages 5–16
• Ginzel, Friedrich Karl, "Die Wassermessungen der Babylonier und das Sexagesimalsystem", Klio: Beiträge zur alten Geschichte, 16 (1920), 234-241.
• Planchon, "L'Heure Par Les Clepsydres." La Nature. pp. 55–59.
• Thureau-Dangin, François, "La clepsydre chez les Babyloniens [Notes assyriologiques LXIX]", Revue d’assyriologie et d’archéologie orientale, 29 (1932), 133-136.
• Thureau-Dangin, François, "Clepsydre babylonienne et clepsydre égyptienne", Revue d’assyriologie et d’archéologie orientale, 30 (1933), 51-52.
• Thureau-Dangin, François, "Le clepsydre babylonienne", Revue d’assyriologie et d’archéologie orientale, 34 (1937), 144.

Spoljašnje veze

• http://www.marcdatabase.com/~lemur/dm-gitton.html#iw-time-flow-clocks Arhivirano na sajtu Wayback Machine (9. avgust 2011)
• https://web.archive.org/web/20060206181901/http://www.perseus.tufts.edu/GreekScience/Students/Jesse/CLOCK1A.html
• http://physics.nist.gov/GenInt/Time/time.html
• http://www.ubr.com/clocks/pub/clep/clep.html
• The Clock of Flowing Time in Berlin Arhivirano na sajtu Wayback Machine (18. januar 2019)
• NIST: A Walk Through Time
• Bernard Gitton's Time-Flow Clocks Arhivirano na sajtu Wayback Machine (9. avgust 2011)
• Egypt's Water Clock Arhivirano na sajtu Wayback Machine (28. septembar 2011)
•  „Clepsydra”. Encyclopedia Americana. 1920. 
• A Brief History of Clocks: From Thales to Ptolemy Arhivirano na sajtu Wayback Machine (6. februar 2006)
• The Indianapolis Children's Museum Water Clock
• Nanaimo, BC Water Clock
• Shockwave-Applet: Ctesibius Waterclock
• Rees's Universal Dictionary article on Clepsydra, 1819
• The Royal Gorge Bridge Water Clock
•  „Clepsydra”. New International Encyclopedia. 1905. 
• The Mechanical Water Clock Of Ibn Al-Haytham