His first recorded works, designed in collaboration with Addison Hutton (a former draftsman in his employ), were the Connecticut State Hospital in Middletown, dating from 1886, and St. Charles Borromeo Seminary in Philadelphia, built about the same time.
Other early buildings attributed to Mr. Sloan include the old Masonic Temple, the Tradesman’s National Bank, and the Pennsylvania State Building at the 1876 Exposition in Philadelphia. He also designed the Fulton Opera House at Lancaster, Pa., a four-story Mid-Victorian structure erected in 1852, in more recent years remodeled for a Moving Picture Theatre.
In addition to his work in professional practice Mr. Sloan served as Editor of the magazine "Architectural Review” in 1868, published a number of books, Including "City and Suburban Architecture" (1859) and "Constructive Architecture," also prepared numerous articles for publication in architectural magazines.
In his latter years (1874-84) Mr. Sloan designed a large number of hospitals and asylums, also many residences in the southern states.
One of the most distinguished of early American architects, a charter member of the Philadelphia Chapter, A.I.A. and a Fellow of the Institute.