is so great that the utmost energy will be requisite in conducting the necessary observations, and can be effected in any reasonable time only, by skilfully combining them with the changes of seasons which take place at alternate periods of the year to the north and south of the Equator. On the approach, therefore, of the monsoon to the coast of Peru, you are to make the utmost expedition in removing both vessels to California, where San Francisco offers a healthy and convenient spot for fresh rating the chronometers.
Little is known of this great country except that it is rapidly increasing in population and commerce; and as it contains but kw harbours, its shores steep, and the approaches bold, there will be little motive for detention between San Francisco and the district visited by Captain Vancouver.
You will then have an excellent opportunity of verifying the longitudes of two or three of the above officer's principal points, which differ materially from those which Senor Quadra and the Spaniards have assigned to them, and on which therefore depends the whole form of that coast.
From this region you will again pursue the survey to the southward along to the shores of Guatemala and Mexico, and so on, alternately changing your ground according to the periodic change of weather, till in a succeeding season you will have met the operations proceeding to the northward. With the very dubious knowledge which exists of the periods of the winds, or of the changes of wet and dry weather, which prevail along the great continent, and the still less knowledge of the character of the shores, which will in some places delay, and in others rapidly accelerate your progress, it is impossible
