SATLING.
For the purpose of climatological study the surface of the ocean is supposed to lie divided into rectangular areas by the even five-degree parallel, of latitude and meridians of longitude, 5°, 10°, 15°, ete. The Pilot Chart for any month gives in blue for each of these areas the atmos pheric pressure and temperature prevailing under normal conditions, the average force of the the number of hours within the month during which the Wind may be expected to blow from a given quarter. and the frequency of calms. derived from a discussion of the obscrra tinics taken within the same month during pre vious years. All of this is shown symbolieally upon the face of the chart. Thu addition to this there is also given in blue a brief text, contain ing a fort-east or statement of the average con ditions that may be expected during the month for the more frequented parts of the ocean. the probability of storms, the nature of these §.;torm?t, the frequency of fog (upon the Pilot Chart of the North Atlantic Ocean this is also shown g.raphieally upon the face of the chart), and the limits within which dangerou., masses of floating ice may lie expected. The proper sailing and steamship routes for the given month and the limits of the trade winds are also exhibited.
The information given in red is in the nature of a review. Upon the Pilot Chart of the North Atlantic Ocean it comprises a brief account of the main features of the weather over that ocean during the month preceding the date of publica tion of the chart. The path followed oy 1 centre of each of the more important barometric depressions that have occurred within that period is shown, and the force of the winds which ac companied them, the latter on the Beaufort scale. The region through which fog ha, been frequent is also shown. Upon the Pilot Chart of the North Pacific Ocean there the average track followed by the centres of the barometric depressions for the month that occurred during the ten-year period D478-1887; also the tracks followed by the centres of the various classes of typhoons, those terrific storms which render navigation in East Asiatic water; so fraught with danger. Upon both charts is given in red the last reported position of floating derelicts, wreck age, buoys, and other obstacles to navigation.
Recently reported icebergs and field ice are also shown, all of these being plotted upon the chart precisely IN here last sighted, in order that the mariner may have the dangers which menace his %essel constantly in view, .without dependence upon his memory and without reference to any publication save the chart before him.
Other features of the chart are the list of equator crossings for several future months. in tended for the use of vessels hound on distant voyages; the list of new charts recently published and of additions and corrections to old; the storm warnings displayed by the United States and by other maritime nations, all of which are shown graphically. In addition to these the land space cf the chart is always devoted to a discussion of some topic of interest to navigators, such as studies in the law of storms, the experience of various vessels in recent cyclones, recent improve ments in the theory and practice of navigation. the relative advantages of different sailing routes, and other similar subjects. The reverse of the chart is also frequently utilized for this purpose, one of the interesting publications of the United states Hydrog.raphie Office being the chart which appears annually upon the back of the Pilot ('hart, showing the drift of sealed bottles which are cast overboard in various parts of the ocean and find their way to distant shores.
As in the days of Manry, so now the 'United States Government is still the pioneer in this class of publications for the benefit of seamen. The first edition of the Pilot Chart of the North Atlantb' Ocean appeared in December. ISS3, that of the North l'acifie Ocean in January. I894. The German Government and also the have recently entered the field, each of these having in January. 1901, begun the publication of a chart of the North Atlantic embodying many of the features of the American Pilot Chart. The Ger man chart bears the title Yordathintische Met teraussehau. and is published monthly by the Deutsche Seevarte. Hamburg. Germany. The British Pilot ('hart extend: also over the Mediter ranean Sea. and is published monthly by the Meteorological Office in London. See HYDRO GRAPHIC OFFICE.