In 1885 Swasey completed work at McCormick Observatory on the 45-foot dome, which was the largest in the world, and had a unique, 3 shutter design. In 1887 Swasey built the mount for the 36-inch refracting telescope at Lick Observatory. In 1898 he manufactured a dividing engine for the U.S. Naval Observatory that was used to make the meridian circles. Both the building and dome of the Dominion Astrophysical Observatory were made by Warner and Swasey Co. Other observatory telescopes and components were built by the company at the Kenwood Observatory, Yerkes Observatory, Argentine National Observatory, the Swasey Observatory at Denison University, and the Case School of Applied Science Observatory.