IsiThuba

IsiThuba isilekeleli esigcina futhi siphinde sikhombhise isikhathi. Isithuba singezinyeni zezilumbho ezindala zabantu omsebenzi waso kwakungukulinganisa isikhathi kumzingo omufishane kunaleyo yemvelo efana nosuku, inyanga elinganiswa ngokthwasa konyezi kanye neNkathi yonyaka. Abantu sebesebenzise izilekeleli ezisebenza ngezindlela ezehlukileyo ukugcina isikhathi cishe iminyaka engamakhulunyaka. , pp. 103–104.

Izandulela zithuba zamanje zazisuselwe ekuthwaseni kwimvelo: ithunzela likhombhisa isikhathi ngokusebenzisa ilanga kanye nesithunzi esidalwa induku yaso. Kunezinhlobonhlobo zeziqophasiyiba, esidume kakhulu nje ilesi sesihlabathi (Hourglass). Isiqophasiyiba samanzi, kanye naleso seLanga zingezinye zezilekeleli ezokugcina isikhathi ezindala kakhulu. Ukulunjwa kwesizinge, okuyikho okwaholela ekulunjweni kwezithuba ezinguxazelayo ngeminyaka ye-1300 eYurophu, zona ezazigcina isikhathi ngokusebenzisa izithekezelo kuhle kwezabelasisindo.
Awukho umehluko phakathi kwesithuba sasendlini kanye naleso sesihlakala, phela zombhili zenza umsebenzi ofanayo, okungukugcina ziphinde zikhombhise isikhathi. izithuba ezisebenzisa izizwayizwayi zaqala ukwakhiwa ngekhuluminyaka eliyi-15. Phakathi kwekhuluminyaka le-15 kuyela  kwele-16, ukukhandwa kwezithuba kwanda kakhulu. Ukulangaba okwalandela kwaba yilokho bokuqikelela umnembo okwenzeka emva konyaka we-1656, lapho uChristiaan Huygens esethule isithuba sosulu. Enye yezinto eyayiqhuba ukwakhiwa kwezithuba ezinembhayo ekugcinweni kwesikhathi, ileyo yokutilosa olwandle. IziThuba ezisebenza ngamazuba zanelwa ngonyaka we-1840, kuthi izithuba zona zathulwa ngekhuluminyaka lama-20. Ukwakhiwa kwezigcinazuba ezincane yikho kanye okwadala ukuthi zisabalale kakhulu izithuba.