Hosack entered into a professional partnership with his mentor [[Samuel Bard]] around 1795, assuming sole responsibility for the practice upon [[Samuel Bard|Bard's]] retirement in 1799. Having tended victims of yellow fever in 1795 and 1798, Hosack promoted new procedures for preventing and treating contagious diseases, including visionary city planning measures, such as eliminating narrow streets and alleys and lining [[walk]]s and [[cemetery|cemeteries]] with specific types of trees to provide shade, purify the air, and beautify the city <span id="Hosack_1820_cite"></span>([[#Hosack_1820|view text]]). Hosack also took a great interest in New York's cultural life. His home functioned as a salon where American writers and artists mingled with physicians and scientists. Hosack's extensive art collection was similarly eclectic, mixing contemporary American landscape painting, such as [[John Trumbull]]'s ''Niagara Falls, from Two Miles Below Chippawa'' [Fig. 2], with Italian Old Masters. Among the artists patronized by Hosack was the young English painter Thomas Cole (1801-1848), who immigrated to America in 1818 and became one of the founders of the Hudson River School of landscape painters. In November 1826 Hosack sent Cole a printed invitation requesting his company “Sunday evenings, during the winter.”<ref>Robbins, 1964, 168, [https://www.zotero.org/groups/54737/items/itemKey/CQCQ247B view on Zotero].</ref> Three years later, Hosack purchased Cole's ambitious Biblical landscape painting, ''Expulsion from the Garden of Eden'' [Fig. 3].
That same year, Hosack made a far more extravagant purchase, acquiring the principal section of [[Hyde Park (on the Hudson River, N.Y.)|Hyde Park]], the Hudson River estate of his deceased partner [[Samuel Bard]]. Hosack thereafter retired to his new country seat, devoting the rest of his life to carrying out an ambitious plan for landscaping the grounds. The estate became well known for its dramatic views of the Hudson River as well as for the elaborate network of gardens, walks, and drives that Hosack laid out there. Attracted by the international fame of [[Hyde Park (on the Hudson River, N.Y.)|Hyde Park]] as one of America's finest estates, and by Hosack's reputation for generous hospitality, tourists exploring the Hudson River invariably made a stop there. It became a favorite subject of travel accounts and works of art, which provide far more detailed information about the design of the grounds than is common for early nineteenth-century gardens.
Changes - History of Early American Landscape Design