"Prepare the wonder-working fabric of the terrestrial and stellar sphere." That is a Sanskrit textbook instructing the teacher to build an armillary sphere — a working model of the heavens, rings for the ecliptic and the asterisms around a globe of the Earth — for the instruction of the pupil. The Sūrya-Siddhānta's closing chapters specify the instrument kit of classical Indian astronomy: the sphere, the gnomon, and the water clock that timed the observations behind its one-second lunar parameters.