Surya Siddhanta
गुरूपदेशाद् विज्ञेयम् कालज्ञानम् अतन्द्रितैः। तोययन्त्रकपालाद्यैर् मयूरनरवानरैः। ससूत्ररेणुगर्भैश् च सम्यक् कालम् प्रसाधयेत्॥
According to the instruction of the preceptor (guru), is to be gained a knowledge of time by the diligent, by water-instruments, the vessel (kapala), etc., by the peacock, man, monkey, and by stringed sand-receptacles, one may determine time accurately.
english translation