The construction and use of several types of instruments are described in many Sanskrit texts on astronomy. But there is no documentation of extant specimens where one could see how the textual prescriptions were followed in practice. Therefore I decided to make a survey of museums and identify pre-modern astronomical and time-measuring instruments.

Between 1991 and 2005, I visited more than a hundred museums and private collections in India, Europe and North America, and prepared a descriptive catalogue of all extant specimens. The catalogue consisting of 600 entries in a little over 4300 pages is now freely accessible at my homepage: (http://www.srsarma.in/index.php).

In this lecture, after a brief overview of the online catalogue, I shall discuss two Sanskrit instruments and two Indo-Persian instruments, namely Ghaṭikā-yantra, Dhruvabhrama-yantra, celestial globe and astrolabe. The Ghaṭikā-yantra was used for measuring time and the Dhruvabhrama-yantra for determining certain parameters for drawing horoscopes.

The celestial globe and the astrolabe were invented in Greece; the Islamic world introduced many improvements and transmitted them to Europe and India. In India, Muslim instrument makers produced some very fine celestial globes and astrolabes. The astrolabe attracted the attention also of Hindu and Jaina astronomers who extolled it as Yantrarāja.

I conclude the lecture with Bulhomal of Lahore, the last great instrument maker who created—around the middle of the nineteenth century—several kinds of traditional instruments and engraved some in Persian and some in Sanskrit.