towards the compass will, when the ship's head is N., E., S., or W. produce no deviation. When N.E. and S.W. it produces a deviation to the right hand or E., and when S.E. or N.W. a deviation to the left hand or W.; it therefore produces what is called the quadrantal deviation.

"A horizontal soft iron rod directed to the compass, but placed to starboard or port, will produce an effect of exactly the opposite kind, and would correct that produced by the first rod; but if the second rod, instead of being on one side, passes, as it were, through the compass, it would produce exactly the same effect as the first rod. The two rods will then conspire to produce the quadrantal deviation.

"A quadrantal deviation of the same kind will be produced if the first rod instead of being on one side of the compass passes through it, provided always that its force is less than that of the transverse rod." Hence

The quadrantal deviation, represented in the formula p. 740 by d = D sin 2 z + E cos 2 z, arises from horizontal induction in soft iron, and, in an iron ship, it is not alone the horizontal soft iron near the compass that gives it, but all connected with the hull, keel, frame and fittings trending athwartship, fore and aft, and diagonally, over, under, and in the plane of the compass; in addition to which, in a steamer, there are the engine, screw-shaft, &c. Some of this iron gives a positive, and some a negative, quadrantal deviation, but the difference of the two is, in the majority of cases+ D, it being rare to find D; and from the fact that the positive deviation is accompanied with a diminished directive force the effect of the transverse iron most probably preponderates.

The coefficient D produces the greatest error on the N.E., S.E., S.W., and N.W. points of the compass, and D. in the formula gives or E deviation in the N.E. and S.W. quadrants, and or W. deviation in the N.W. and S.E. quadrants. Fig. 18.

D is the reverse of the foregoing, giving + or E. deviation in the N.W. and S.E. quadrants, and or W. deviation in the N.E. and S.W. quadrants. Fig. 19.

The coefficient E arises from horizontal induction in soft iron which is unsymmetrically distributed in relation to the position of the compass, and at an angle with the midship line. Its maximum effect is found at the four cardinal points, giving nil at N.E., S.E., S.W., and N.W. In a sailing ship it does not exceed 2°, and is usually less; but in a steamer, with the steering wheel brought forward, before the engine, it is often more.

(To be continued.)

W. H. R.

To the Editor of the "Nautical Magazine." IR,-Parliament having re-appointed the Committee on the Rule of the Road at Sea, the present seems to me a favourable opportunity to raise, in the pages of the Nautical, a discussion on the new Rule of the Road which has become law this month. I begin by contributing the following remarks on what appear to me to be, in the applica tion of the Rules by night, either important omissions or dangerous ambiguities in the new Rules, now law.

When a steamer has a tow astern that condition is indicated to approaching vessels by the two masthead lights on the steamer. The object announced is thereby known to be not simply a steamer or simply a sailing vessel, but both. Is the approaching vessel to consider that that double object is bound to act as a steamer, or as a sailing vessel? An approaching sailing vessel might

reasonably enough treat the double object as a steamer only, and stand on to it, and such may safely be said to be the general practice.

Now let us suppose that the approaching vessel is a steamer seeing the two masthead lights a point or two on her own port bow. Is the tow in every case to keep out of the way of the steamer seen to starboard according to Article 16?

In the first case the approaching sailing vessel may have a fair wind and be running down on the towing steamer, which may at the time be labouring against a strong head wind and sea, and with scarcely steerage way sufficient to keep her head to it. Would it not be well to define that these special circumstances, if clearly made known to the approaching vessel, are to be considered such as by Article 24 require the exercise of precaution, and consequently action, on the part of that approaching vessel; that is to say, if a steamer having a vessel in tow and only holding her own through stress of weather shall indicate that condition to approaching vessels by hoisting, in addition to her usual lights, say, a red light 3 feet below her masthead lights, that vessel shall then be treated by all other vessels as a vessel not under command.

A steamer even without a tow is, also, as compared with a sailing vessel running down upon her with a fair wind, often helpless through stress of weather. The same signal should therefore be exhibited by such a steamer, say a long passenger steamer with difficulty keeping herself out of the trough of the sea. The sailing vessel approaching her with a fair wind should not expect that steamer to endanger the lives of all on board by endeavouring to get out of her way, when a few spokes of the helm is all she requires on her part, not even touching a brace. The absolute necessity of such a rule appears to be more urgent when we consider that the steamer's position is probably known to the sailing vessel long before the existence even of the sailing vessel becomes known to the steamer, not only by the greater range of the masthead light but also by the distinguishing coloured side-lights, which, in such a steamer, are always the best and most powerful procurable for money, while those of the sailing vessel are often just what will barely pass

F

inspection. The time between the sailing vessel being first seen and possible collision would generally be too short for any effective action on the part of such a steamer.

When these possible cases are thought out it becomes conceivable that with a clever counsel a court would give judgment in favour of such an action, even on the Rules, as they now stand, in respect to the steamers in both of these cases.

In fog or thick weather vessels are supposed to make known what they are by arranged sound-signals; but what fog-signal is prescribed for a sailing vessel in tow? It would only confuse the other vessel to adopt the signals denoting how she has the wind, for her course is not at all maintained by the wind, but by the steam power of the tug-boat. If the towing steamer could intimate that she has a vessel in tow that would be perhaps sufficient, but the Rules do not at present provide any sound-signal to announce distinctively the presence of a steamer with a vessel in tow. The sound-signal of a steamer towing is precisely the same as that for any other steamer, and in a fog a steamer having another steamer signalled on her own starboard bow would aim to clear that steamer by going, say, under her stern, and would have no notice of there being a sailing vessel towed astern with perhaps 90 fathoms of hawser intervening.

There does not appear to be any objection to the ringing of a bell by a vessel in tow in a fog. This signal could not clash with the anchor-signal if the Rule be that the bell shall be rung immediately after each steam-whistle signal made on board the towing steamer.

An important question sometimes arises, do the Rules impose any duty on a hove-to vessel by night beyond making her position known? Is a hove-to vessel to be considered by those in charge to be a vessel not under command, and therefore prescribed for in Article 5, viz., that she, as "not making any way through the water, shall not carry the side-lights." A similar question arises in regard to vessels becalmed-are they to exhibit their side-lights?

To every approaching vessel the vessel becalmed is an overtaken ship, and as such is provided for, whatever be the direction of approach, for while becalmed the distinction between head and

stern is lost. The stern-light exhibited in the direction in which a steamer is seen to be approaching would be readily understood in this case, but a hove-to ship ought to be otherwise distinguished.

While permitting the handicapped towing steamer to claim forbearance from vessels possessing greater freedom of action, the towing steamer has not as above proposed been allowed to represent herself quite as a vessel disabled by accident; her sidelights being still exhibited announce her to be a vessel trying to make way, overpowered by the weather, but not herself disabled. In the case of the hove-to vessel would it not do to exhibit, in addition to her side-lights, an anchor light three feet above the fore end of the leeward light screen? She is already protected by Clause (a) of Article 14, from vessels on her weather side.

In fog or thick weather perhaps the bell would be the best signal for a vessel hove-to on the port tack while on the starboard tack by Clause (a) no distinguishing hove-to signal would be requisite.

To illustrate the need of some such method for distinctly signalling the condition of the hove-to vessel when her state cannot otherwise be known to approaching vessels, let us suppose two ships, one making headway on the starboard tack and the other hove-to on the port tack, perhaps to take deep-sea soundings, or it may be waiting for daylight to enter port, or for a pilot. The ship on the starboard tack should, by the Rules, keep on her course trusting that the other vessel is making headway on the port tack. By daylight, however, the ship close-hauled on the starboard tack, if handled according to the ordinary practice of seamen, would, even in the finest weather, keep clear of the hove-to vessel. In bad weather it might be positively dangerous to require the hoveto vessel to take up the responsibility of keeping out of the way of any approaching vessel, which by the Rules is directed to keep her course, because of the difficulty of getting way on the hove-to vessel in time to avoid collision, and because of the risk to a small vessel when falling off into the trough of the sea.

In a fog if the vessel hove-to on the port tack carries out the Rule for sound-signals all vessels approaching her will be misled