Senex is famous for his maps of the world, some of which have added elevations, and which feature minuscule detailed engravings.
Many of these maps can be found in museum collections; rarely, copies are available for private sale.
Some copies are held in the National Maritime Museum; many of his maps are now in the possession of Trinity College Dublin.
Having worked and collaborated with Charles Price, Senex created a series of engravings for the London Almanacs, and in 1714 he published together with Maxwell an English Atlas.
He became particularly interested in depicting California as an island instead of part of mainland North America, a trait which makes many of his maps appealing to collectors.