unfortunately, by the time atlantic explorers were seeking information in the 1490s, the "inventio" had gone missing, and was only known through a summary in a second text, the "itinerarium," written by a brabantian traveller from 's-hertogenbosch named jacobus cnoyen (also known as james cnoyen or jakob van knoyen; modern knox). as will be discussed below, cnoyen's summary was the basis for the depiction of the arctic region on many maps, one of the earliest being martin behaim's 1492 globe. by the late 16th century, even cnoyen's text was missing, so most of what we know of the contents of the "inventio fortunata", other than its use on maps, is found in a letter from the flemish cartographer gerardus mercator to the english astronomer john dee dated april 20, 1577, now located in the british museum.