“This voyage,” we are told, “proved to be the most important to geography that had been undertaken since the first circumnavigation of the globe.” Tasman sailed from Batavia in the yacht _Heemskirk_, on the 14th of August, 1642, and from Mauritius on the 8th of October. On November 24 high land was sighted in 42° 30´ S., which was named Van Diemen’s Land (now Tasmania), and, after landing there, sail was again made, and New Zealand (at first called Staatenland) was discovered on the 13th of December. Tasman communicated with the natives and anchored in what he called Murderers’ Bay, because several men were massacred there by the natives. Thence he took an irregular course east and north, until he arrived at the Friendly Isles of Cook. In April, 1643, he was off the north coast of New Guinea, having meanwhile sailed around New Britain and New Ireland (now New Mecklenburg), and on June 15 he returned to Batavia. The contribution to sea-knowledge of the remaining voyages in this century were mainly in the direction of a better understanding of winds, currents, ice movements, tides, and an improvement in the methods of building, rigging, and navigating vessels intended for long voyages. Map-making received a great impetus and was especially cultivated by the Dutch, among whom Mercator became famous by inventing the useful projection that bears his name and is still most commonly used. Nevertheless, the improvement, especially in instruments of navigation, was slow. The astrolabe generally gave place to the cross-staff; and this to a better device called the back-staff, of which an improved form, invented by John Davis, remained long in use. This was called the Davis quadrant; and with it “the observer stood with his back to the sun, and, looking through the sights, brought the shadow of a pin into coincidence with the horizon.” Many variations of this instrument were made, until, in the middle of the next century, it was superseded by the sextant. Thus before the close of the seventeenth century, astronomers and navigators had learned how to determine latitude fairly accurately, and the sailor had prepared for him a variety of tables of stars, almanacs, and other mathematical guides. The determination of longitude was yet difficult, however, owing largely to the imperfection of timepieces; and it was not until the last year of the century, signalized by the first recorded sea-voyage made purely for scientific purposes, that much advance was made. This voyage, lasting two years (1699-1700), was undertaken by the eminent English astronomer Edmund Halley for the express purpose of obtaining information necessary to the improvement of the compass and methods of ascertaining the position of a ship at sea, was productive of results of the greatest service, and placed the science of navigation upon a sure footing. It was followed early in the next century by the establishment in England of the Longitude Board, a scientific