'Comparitive Analysis of Jose de Mendoza Rios's method for reducing the lunar distances...' Mendoza Rios's work was (he believed) a refinement of lunar distance method of determining longitude (a lunar distance is the distance between the moon and the sun or a fixed star. By comparing the local time when the lunar distance was observed with time predicted for the same lunar distance to occur at a known meridian, the difference in longitude could be deduced). c.1814