The grandson of the late Indian independence leader Mahatma Gandhi will speak in Lexington next weekend about Indian and American history. Rajmohan Gandhi, a professor at the University of Illinois, will be in the Lexington Depot, at 13 Depot Square, at 7 p.m. Saturday for a lecture and book signing. The event is cosponsored by the Indian Americans of Lexington and the Lexington Historical Society in an effort to increase understanding of the parallel histories of India and the United States. Gandhi, a research professor at the university’s Center for South Asian and Middle Eastern Studies, is the author of a biography of his grandfather, and “A Tale of Two Revolts,” which draws comparisons between the 1857 Indian Mutiny and the American Civil War. Tickets to the lecture, book signing and a dessert are $10. Tickets can be reserved by calling the historical society at 781-862-1703, or by e-mailing firstname.lastname@example.org.