[en.wikipedia.org]


Seamless celestial globe

In the 1980s, Emilie Savage-Smith discovered several celestial globes without any seams in Lahore and Kashmir. Hollow objects are typically cast in two halves, and Savage-Smith indicates that the casting of a seamless sphere is considered impossible, though techniques such as Rotational molding have been used since at least the '60s to produce similarly seamless spheres. The earliest seamless globe was invented in Kashmir by the Muslim astronomer and metallurgist Ali Kashmiri ibn Luqman in 1589-90 (AH 998) during Akbar the Great's reign; another was produced in 1659-60 (1070 AH) by Muhammad Salih Tahtawi with Arabic and Sanskrit inscriptions; and the last was produced in Lahore by a Hindu astronomer and metallurgist Lala Balhumal Lahuri in 1842 during Jagatjit Singh Bahadur's reign. 21 such globes were produced, and these remain the only examples of seamless metal globes. These Mughal metallurgists used the method of lost-wax casting in order to produce these globes.