MARINE Chair, a machine invented by Mr Irwin for viewing the satellites of Jupiter at sea, and of course course determining the longitude by their eclipses. An account of it is given in the Journal Etranger for March 1762. An account of its accuracy was published the year following by M. de l'Isle astronomer in the Imperial academy of Peterburgh: but notwithstanding the encomiums bestowed upon it by this gentleman, it hath never come into general use; and therefore we may conclude, that it is much inferior to the inventions of Mr. Harrison for the same purpose. See HARRISON and LONGITUDE.