gravier's most enduring work was his compilation of a kaskaskia-french dictionary, with nearly 600 pages and 20,000 entries. the manuscript is held by trinity college in hartford, connecticut. it is the most extensive of dictionaries of the illinois language compiled by french missionaries. the work was finally edited and published in 2002 by carl masthay, providing an invaluable source of the historic "kaskaskia illinois" language.