The poet Chaucer and the scholar Nicholas had tastes in common. Both loved music and both studied what was then known of the sphere and the means of fixing positions. Chaucer wrote a treatise on the astrolabe addressed to his little son Lowys in 1391 and called it “brede and milke for children.” In this treatise Chaucer mentions Nicholas with great respect. We shall not be far wrong either in assuming Nicholas the scholar to have been a friend of Chaucer, or in identifying him with the Carmelite monk Nicholas of Lynn, who would take his place as England’s first Arctic explorer if his work had not been lost--a loss which is almost a national calamity. In 1360 Nicholas of Lynn undertook an expedition to Norway and the isles beyond towards the pole, beginning from 54° N. and fixing the latitudes with an astrolabe. Hakluyt quotes Gerard Mercator as writing that an English monk and mathematician of Oxford had been in Norway and the islands in the north, describing all those places and determining their latitudes by an astrolabe. He is said to have written a work on his expedition entitled _Inventio Fortunata_, which is lost; and another work is attributed to him, _De Mundi Revolutione_. Dr Dee wrote that Nicholas made five voyages into the northern parts, and left an account of his discoveries. Dr Nansen is the first writer I know who treats Nicholas of Lynn seriously. He shows that the work of Nicholas was known to Las Casas, who had read it, and also to Martin Behaim, who on his globe places isles all round the pole which are not shown on any older map and, Nansen thinks, are evidently taken from Nicholas of Lynn. The maps of Claudius Clavus, one of them quite recently brought to light, and other medieval maps, also probably derived their information from our forgotten Nicholas. One would give a good deal to know which were the northern islands that he visited. Evidently his work had an influence on the productions of the cartographers through the next century. [Illustration: The Zeni map.] We owe much to the cartographers, and it is deeply interesting to watch their gradual acquisition of fresh knowledge, and their treatment of uncertain and disputed points. But there have been cartographers of a different kind who have invented and knowingly led students and navigators astray. If such men gain a hearing, the injury they do may endure for a century or more. Such a man was Niccolo Zeno.