A large digitization project by the U. of Chicago that includes searchable French dictionaries from the 16th, 17th, 18th, & 19th centuries (can be searched together or separately): Dictionnaires d'autrefois and the FRANTEXTdatabase of over 3000 keyword-searchable works of French literature and non-fiction from 12th to the 20th century, an excellent corpus for language usage over time. Searches can be limited by time period, genre, author and title. (See also other ARTFL literature collections and others listed under "Electronic Texts in French" above.)
Note: ARTFL includes both subscription and public access databases. All public access databases may be accessed (on and off campus) from the ARTFL Public Databases page.