Nichol's used his public lectures to popularize the nebular hypothesis, the theory that the solar system originated from a nebula. This is the current theory of how the solar system formed. Nebulae are large clouds of hydrogen gas. Gravity among the hydrogen molecules causes them to clump together. Stars form from the clumps of hydrogen when the gravitational pressure causes the hydrogen to begin nuclear fusion creating helium. This process takes over a hundred million years in the case of a sun sized star.
Nichol was responsible for the erection of new observatory on Horselethill in the west end of Glasgow and his family lived in a attached house. In addition to his public lectures Nichol was a prolific writer, publishing many popular books of science. His most famous book Views of the Architecture of the Heavens went through seven editions in seven years and won praise from popular writer George Eliot.
He died on September 19, 1858.
Clerke, Mary Agnes; "Nichol, John Pringle"; Dictionary of National Biography, 1885-1900; Vol. 40.
Anon.; "John Pringle Nichol"; Biography from the University of Glasgow.
John Pringle Nichol Wikipedia Entry