In Lloyd's Rooms, at London, there is a curious weather gauge. It is an index turned by the vane on the roof, constantly showing by the vane below the direction of the wind, while a pencil is attached to a chart, and moved by the same power, so as to mark the precise course in which the wind has been blowing for days ; making a record as distinct as ' the pencilled course of a ship on the master's chart at sea Studying this map of the winds, an insurer may make some calculation upon the progress of a vessel, and shape his business accordingly.