Shabnumā-wa-Rūznumā A Rare Astronomical Instrument Extant in Two Specimens

Abstract

In India, there are extant two nineteenth century specimens of an otherwise unknown astronomical instrument called Shabnum?-wa-R?znum? with which observations can be done both in the day and at night. While the R?znum? is nothing but a sine/horary quadrant, the Shabnum? appears to be inspired by the Sanskrit instrument Dhruvabhrama-yantra which was invented by Padman?bha in the first quarter of the fifteenth century in Central India. After a brief description of the Dhruvabhrama-yantra, the two specimens of the Shabnum?-wa-R?znum? are described in detail.