Astronomy
T1
The entire observatory is a stick. Sūrya-Siddhānta chapter iii: level a floor, draw a circle, stand a twelve-digit gnomon at its center — and from where the shadow's tip crosses the circle morning and evening, construct true east-west; from the noon shadow at equinox, your latitude; from any noon shadow plus the sun's declination, latitude on any day of the year. Burgess, the 1860 translator, test-drives the rules on Washington, D.C. (38°54′) and they work. Positional astronomy bootstrapped from a shadow — no metal, no glass, no moving parts.
From the source
“At its centre set up the gnomon, of twelve digits of the measure fixed upon ; and where the extremity of its shadow touches the circle in the former and after parts of the day ”
Well-supported