This long lamp, with a handle and counter-balancing rest at one end, and the well for the oil at the other, would have been used for prayer (puja) purposes in South India. The form is relatively common but the cast brass nandi figure facing the lamp that has been cast to the end of the handle, and the seven shiva-lingams around the rim of the lamp bowl make this example unusual.
The lamp dates to the late 19th or early 20th centuries and is from southern India.
References
Anderson, S., Flames of Devotion: Oil Lamps from South and Southeast Asia and the Himalayas, UCLA Fowler Museum of Cultural History, 2006.
Kelkar, D.G., Lamps of India, Publications Division, Ministry of Information and Broadcasting, India, 1961.
Rawson, P., Tantra, Arts Council of Great Britain, 1971.