Page:A Voyage to Terra Australis Volume 1.djvu/8

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these coasts, would be an useful addition to the charts; not only as it would enable those who may navigate by them alone to form a judgment of what is to be expected at the same season, but also that it may be seen how far circumstances prevented several parts of the coast being laid down so correctly as others. This has been done by single arrows, wherever they could be marked without confusion; they are more or less feathered, proportionate to the strength of wind intended to be expressed, and the arrows themselves give the direction. Under each is a short or abridged word, denoting the weather; when this weather prevailed in a more than usual degree a line is drawn under the word, and when in an excessive degree there are two lines. Single arrows being thus appropriated to the winds, the tides and currents are shown by double arrows, between which is usually marked the rate per hour.

On the land, the shading of the hills gives a general idea of their elevation, and it has been assisted by saying how far particular hills and capes are visible from a ship's deck in fine weather; this will be useful to a seaman on first making the land, be a better criterion to judge of its height, and those hills not so marked may be more nearly estimated by comparison. Behind different parts of the coast is given a short description of their appearance, which it is conceived will be gratifying to scientific, and useful to professional men. The capes and hills whose positions are fixed by cross bearings taken on shore or from well ascertained points in the track, as also the stations whence bearings were observed with a theodolite, have distinguishing marks; which, with all others not before in common use, are explained on the General Chart, Plate I.

To have laid down no more than the lands and dangers seen in the Investigator and other vessels under my command, would have left several open spaces, and obliged the seaman to have recourse to other charts where the difference of positions might have