as to involve risk of collision, then, if they have the wind on different sides, the ship with the wind on the Port Side shall keep out of the way of the ship with the wind on the Starboard Side; except in the case in which the ship with the wind on the Port Side is close-hauled and the other ship free, in which case the latter ship shall keep out of the way; but if they have the wind on the same side, or if one of them has the wind aft, the ship which is to windward shall keep out of the way of the ship which is to leeward.

Two Ships under Steam meeting.-If two ships under steam are meeting end on or nearly end on so as to involve risk of collision, the helms of both shall be put to Port, so that each may pass on the Port Side of the other.

Two Ships under Steam crossing.-If two ships under steam are crossing so as to involve risk of collision, the ship which has the other on her own Starboard Side shall keep out of the way of the other.

Sailing Ship and Ship under Steam.-If two ships, one of which is a sailing ship, and the other a steam ship, are proceeding in such directions as to involve risk of collision, the steam ship shall keep out of the way of the sailing ship.

Ships under Steam to slacken Speed.-Every steam ship, when approaching another ship so as to involve risk of collision, shall slacken her speed, or, if necessary, stop and reverse; and every steam ship shall, when in a Fog, go at a moderate speed.

Vessels overtaking other Vessels.-Every vessel overtaking any other vessel shall keep out of the way of the said last-mentioned vessel.

Where by the above rules one of two ships is to keep out of the way, the other shall keep her course, subject to the qualifications contained in the following article.

Proviso to save special cases.-In obeying and construing these rules, due regard must be had to all dangers of navigation; and due regard must also be had to any special circumstances which may exist in any particular case rendering a departure from the above rules necessary in order to avoid immediate danger.

No Ship under any circumstances to neglect proper precautions.--Nothing in these rules shall exonerate any Ship, or the Owner, or Master, or Crew thereof from the consequences of any neglect to carry Lights or Signals, or of any neglect to keep a proper look-out, or of the neglect of any precaution which may be required by the ordinary practice of seamen, or by the special circumstances of the case.

The diagrams and explanation on the next page (222) will assist the seaman in the practical application of the regulations.

DIAGRAMS TO ILLUSTRATE THE USE OF THE LIGHTS CARRIED BY VESSELS AT SEA,

AND THE MANNER IN WHICH THEY INDICATE

TO THE VESSEL WHICH SEES THEM THE POSITION AND DESCRIPTION OF THE VESSEL THAT CARRIES THEM.

WHEN BOTH RED AND GREEN LIGHTS ARE SEEN.

A sees a Red and Green Light ahead :-A knows that a vessel is approaching her on a course directly opposite to her own, as B; (Fig. 1). If A sees a White Mast-head Light above the other two, she knows that B is a steam vessel.

WHEN THE RED, AND NOT THE GREEN LIGHT IS SEEN.

A sees a Red Light ahead or on the bow:-A knows that either (Fig. 2) a vessel is approaching her on her Port bow, as B; or (Fig.3), a vessel is crossing in some direction to Port, as DDD.

If A sees a White Mast-head Light above the Red Light, A knows that the vessel is a steam-vessel, and is either approaching her in the same direction, as B, or is crossing to Port in some direction, as DDD.

WHEN THE GREEN, AND NOT THE RED LIGHT IS SEEN.

A sees a Green Light ahead or on the bow:-A knows that either (Fig. 4) a vessel is approaching her on her Starboard bow, as B; or (Fig. 5), a vessel is crossing in some direction to Starboard, as DDD.

If A sees a White Mast-head Light above the Green Light, A knows that the vessel is a steam-vessel, and is either approaching her in the same direction, as B, or is crossing to Starboard in some direction, as DDD.

ON THE CHART.

A CHART is a map or plan of a sea or coast. It is constructed for the purpose of ascertaining the position of the ship with reference to the land, and of shaping a course to any place.

The use to be made of the chart in each case determines the method of projection, and the particulars to be inserted. (1.) The chart may be required for coasting purposes, for the use of the pilot, &c., and then only a very small portion of the surface of the globe being represented at once, no practical error results from considering that surface a plane, and a "plane chart" is constructed in which the different headlands, lighthouses, &c., are laid down according to their bearings. The soundings on these charts are marked with great accuracy; the rocks, banks, and shoals, the channels, with their buoys, the local currents, and circumstances connected with the tides, are also noted. (2) Again, for long sea passages the seaman requires a chart on which his course may be conveniently laid down. The track of a ship always steering the same course appears as a straight line (and can at once be drawn with a ruler) on the Mercator's chart. Hence the charts used in navigation are Mercator's charts. (3.) When great circle sailing is practicable, and of advantage, a chart on the "central projection," or gnomic, exhibits the track as a straight line, and is therefore convenient.*

ON MERCATOR'S CHARTS.

(See Norie, pages 126–131; or Raper's " Practice of Navigation," pages 120—127, on

this subject.)

A CHART used at sea for marking down a ship's track and for other purposes, exhibits the surface of the globe on a plane on which the meridians are drawn parallel to each other, and therefore the parts, BH, CI, DK, &c. (Fig., p. 44), arcs of parallels of latitude, are increased and become equal to the corresponding parts of the equator UV, VW, &c. Now, in order that every point of this plane may occupy the same

* The method lately introduced by Hugh Godfray, Esq., M.A., St. John's College, Cambridge, deserves special mention, as its beauty and simplicity will ultimately lead to its general adoption. A chart on the central projection, as stated above, exhibits the great circle as a straight line, and thus it is seen at once, whether the track between two places is a practicable one; hence, also, we have by inspection the point of highest latitude. An accompanying diagram then gives the different courses and distances to be run on each, in order to keep with of a point to the great circle, This chart and diagram is fully described in the Transactions of the Cambridge Philosophical Society, vol. X, part II; and is published by J. D. Potter, Poultry. Mr. W. C. Bergen, of Blyth, Master in the Mercantile Marine, has also published Charts on the Gnomic Projection, and claims to share with Mr. Godfray the credit of proposing the use of this projection for charts in navigation.