The dangerous navigation of the Keys had necessitated their examination at an early date. In 1718, Domingo Gonzales Carranza surveyed them, as well as some portion of the northern coast, with considerable care. His notes remained in manuscript, however, till 1740, when falling into the hands of an Englishman, they were translated and brought out at London under the title, “A Geographical Description of the Spanish West Indies.” But how inefficient the knowledge of these perilous reefs remained for many years is evident on examining the marine chart of the Gulf of Mexico, by Tomas Lopez and Juan de la Cruz, in 1755. The seafaring English, when they took possession of the country, made it their first duty to get the most exact possible charts of these so important points. No sooner had the treaty been signed than the Board of Admiralty dispatched G. Gauld, a capable and energetic engineer to survey the coasts, islands, and keys, east and south of Pensacola. In this employment he spent nearly twenty years, from 1764 to 1781, when he was taken prisoner by the Spanish, and shortly afterwards died. The results were not made public till 1790, when they appeared under the supervision of Dr. Lorimer, and, in connection with the Gulf Pilot of Bernard Romans, and the sailing directions of De Brahm, both likewise engineers in the British service, employed at the same time as Gauld, constituted for half a century the chief foundation for the nautical charts of this entrance to the Gulf. Among the writers of the last century who did good service to American geography, Thomas Jefferys, Geographer to his Majesty, deserves honorable mention. Besides his more general labors, he edited, in 1763, the compilation of Roberts, and some years after the Journal of the elder Bartram; to both he added a general map of the region under consideration, “collected and digested with great care and labor from a number of French and Spanish charts,” taken on prize ships, correct enough as far as regards the shore, but the interior very defective; a plan of Tampa Bay; and one of St. Augustine and harbor, giving the depth of water in each, and on the latter showing the site of the sea wall. Besides those in the Atlas of Popple, of 1772, the following maps, published during the last century, may be consulted with advantage: Carolinæ, Floridæ nec-non Insularum Bajamensium delineatio, Nuremberg, 1775. Tabulæ Mexicanæ et Floridæ, terrarum Anglicarum, anteriarum Americæ insularum. Amstelodami, apud Petrum Schenck, circ. 1775. A Map of the Southern British Colonies, containing the Seat of War in N. and S. Carolina, E. and W. Florida. By Bernard Romans. London, 1776. Plan of Amelia Island and Bar, surveyed by Jacob Blaney in 1775. London, 1776. Plan of Amelia Island and Bar. By Wm. Fuller. Edited by Thomas Jefferys. London, 1776. Plano de la Ciudad y Puerto de San Augustin de la Florida. Por Tomas Lopez. Madrid, 1783.