However, after sending research teams across Central Asia and Europe to collect data based on the knowledge of Islamic and European scientists, Sawai Jai Singh found discrepancies among the readings of the brass instruments that were widely used at the time. To increase accuracy, he scaled up the size of the tools, stabilised them by reducing moving parts and made them resistant to wear and weather by fashioning them out of marble and local stone. Then he used these innovations to build five outdoor observatories in the Indian cities of Jaipur, Delhi, Ujjain, Varanasi and Mathura.