At the time he attained his nineteenth year the frontiers were threatened with Indian depredations and French encroachments. To meet this danger the province was divided into military districts, to each of which an adjutant-general with the rank of major was appointed. George Washington was commissioned to one of these districts, with a salary of L150 per annum. There were many provincial officers (his brother among the number) in Virginia, who had served in the expedition against Carthagena and in the West Indies. Under them he studied military exercises and tactics, entering with alacrity and zeal into the duties of his office. These pursuits were varied by a voyage to Barbadoes, and a residence of some months in that colony, in company with his brother Lawrence, who was sent there by his physicians to seek relief from a pulmonary complaint. Fragments of the journal kept by George Washington on this excursion have been preserved; they evince an interest in a wide range of subjects, and habits of minute observation. At sea the log-book was daily copied, and the application of his favorite mathematics to navigation studied; in the island, the soil, agricultural products, modes of culture, fruits, commerce, military force, fortifications, manners of the inhabitants, municipal regulations and government, all were noted in this journal. Lawrence Washington died in July, 1752, leaving a wife and infant daughter, and upon George, although the youngest executor, devolved the whole management of the property, in which he had a residuary interest. The affairs of the estate were extensive and complicated, and engrossed much of his time and thoughts for several months. His public duties were not, however, neglected. Soon after the arrival of Governor Dinwiddie the number of military divisions was reduced to four and the northern division allotted to Washington. It included several counties, which he had visited at stated intervals, to train and instruct the military officers, inspect the men, arms, and accoutrements, and establish a uniform system of manoeuvres and discipline.