This area of France, formerly a per se "département", is of note in that it is the titular designation of many organizations, conferences, and so forth. Also, in the context of inventor location, when further data is lacking within patent originals, "France (Seine)" is the only information on hand, with specific Parisian addresses often coming up later. We may find no address data, or it may not be quite Parisian. This is key in that the département administrative unit is often the most precise location data, within France, given on French patent originals, whereas Hungarian patent originals pertaining to French inventors will give the city, and British originals will give the address of the inventor, the city, and more.
It is of note that Paris was in the process of broadening throughout the period upon which we are focused. Many département Seine locations are within modern Paris, as such. All are well within any contemporary (to us) conception of the metropolitan area. Modern Paris has special status as both a département and a commune, within the région française Île-de-France. When it existed, as such, Seine was one of the smaller départements français, comprising nothing we wouldn't consider as being within some greater Paris.