Astro : Time Measurement : jalayantra, a water clock, ambu-yantra, tOya yantra, kapālaka, ghaTi, ghaTikā, ghaTI yantra, kaTOrA, kaTorI

Sundials are good during the day time. jalayantrā: are useful for time measurements during the night. All ancient civilisations had some form of water clocks. The concept itself is both elegant and intelligent.

The name kapAlaka specially interests me… because of the connection with kApAlikA… maybe cemeteries were good places to watch the night skies.. and of course astronomers need clocks.


Every day, the moon rises 48 minutes later than the previous day. And this is the duration of a muhūrta: .Therefore there are 30 muhūrtā: in a day. (Reasoning :


A nADikA is half of a muhurta ie., it is 24 minutes (R-VJ, Y-VJ). It is also called nADI, ghaTI, ghaTikA and nAlikA. 

One form of an Ancient Indian Water clock simply emptied itself in a nADikA! In another form it was placed in a larger receptacle of water and slowly filled itself and sank in one nADikA. These clocks were in use as late as early last century in remote places.

From kauTilya arthaśAstra we have “1 náliká, or the time during which one ádhaka of water passes out of a pot through an aperture of the same diameter as that of a wire of 4 angulas in length and made of 4 máshas of gold.”(

Ancient Indian Astronomer Lalla’s description is often referred to. The pot is shaped like the bottom half of a water pot or kalaśa.

  • Material : Copper
  • Weight : 10 palas
  • Diameter : 9 inches at the top (half a cubit)
  • Height : 4.5 inches (half of the diameter)
  • Hole at the bottom made out of a gold wire weighing 3 1/3 mASakA: and drawn into 3 angulA: (3 inches) length.

(Many people scoff at the ‘exact fussiness’ of brãhmaNa rituals. But the smRtI: are firmly rooted in the astronomy and the AyurvEda of the corresponding periods. The bhakti cult eliminated the Science and Technology of the rituals and abstracted only emotion, love and faith or the psychology part of it. And of course the better Science and Technology of the West supplanted the Ancient Indian Technology. Only a curious person person like me, interested in clean and ancient technologies, would study this today. And some people who associate ancient technology with good luck or magic, would perform rituals exactly in the old way confident that it would please the Gods.)

Reference for the  :

  1. Ancient Indian Water Clock :
  2. Duration of muhurta: :



Source for text and image below/right : 

It was commonly used instrument inside the temples of Lord Shiva.  It is the time in which sixty slokas (verses) – each composed of sixty long syllables can be recited.