Editing Secchi disk (section)

==History==
The original Secchi disk was a plain white disk and was used in the [[Mediterranean Sea]].<ref>{{cite web |url=https://www.jeos.org/index.php/jeos_rp/article/view/10013s |title=On the history of the Secchi disc |work=www.jeos.org}} {{webarchive|url=https://web.archive.org/web/20140426220701/https://www.jeos.org/index.php/jeos_rp/article/view/10013s |date=2014-04-26}}</ref><ref>{{cite journal |doi= 10.1007/BF02726911 |title= Relazione delle esperienze fatte a bordo della pontificia pirocorvetta l'Immacolata concezione per determinare la trasparenza del mare; Memoria del P. A. Secchi |trans-title=Report of the experiments made on board the pontifical steam corvette the Immaculate Conception to determine the transparency of the sea; Memoir of P. A. Secchi |journal= Il Nuovo Cimento |volume= 20|issue= 1|pages= 205–238|year= 1864|bibcode= 1864NCim...20..205.|s2cid= 182945407}}</ref> A plain white, {{convert|30|cm|abbr=on}} diameter Secchi disk remains the standard design used in marine studies. In 1899, [[George C. Whipple]] modified the original all-white Secchi disk to "...a disc about 8 inches in diameter, divided into quadrants painted alternately black and white like the target of a level-rod...".<ref>Cialdi, M. and Secchi, P. A. (1865). "Sur la Transparence de la Mer." ''Comptes Rendu de l'Acadamie des Sciences.'' 61: 100–104.</ref><ref>Whipple, George C. (1899). ''The Microscopy of Drinking-Water.'' New York: John Wiley & Sons, 73–5.</ref> This modified black-and-white Secchi disk is the standard disk used in [[limnology]] (freshwater) investigations.<ref name="mlswa.org 1999">{{cite web |title=What is the SECCHI disk? |website=mlswa.org |date=1999-08-28 |url=http://www.mlswa.org/secchi.htm |archive-url=https://web.archive.org/web/20120814094054/http://www.mlswa.org/secchi.htm |archive-date=2012-08-14 |url-status=dead |access-date=2023-03-18}}</ref><ref>{{cite web |url=https://www.nalms.org/secchidipin/monitoring-methods/the-secchi-disk/why-a-black-and-white-secchi-disk/ |title=Why a Black and White Secchi Disk? |work=www.nalms.org |access-date=2012-07-05}}</ref>