GENEEAL EEMAEKS. 4^1 



the best to be pursued, and a vessel should be driven out of her intended 

 route, it does not follow that it is right to endeavour to regain that course 

 to pursue it afresh, but rather it should be considered that a fresh voyage 

 has to be commenced, and the course shaped from the latest point as if it 

 were a starting point. 



(475.) A vessel under steam only is considered in the light of a sailing 

 vessel with a fair wind. In a certain sense this is true, as it enables her 

 to be independent of Wind or Current. But it should be remembered 

 that the same contrarieties which affect and hinder a saihng vessel from 

 pursuing a direct course, will also, in a degree, be adverse to the progress 

 of a steamer ; and, therefore, if a moderate deviation from the shortest 

 route will lead her into more favourable Winds or Currents, that course 

 will be most advantageous to the vessel under steam as it is to the sailing 

 ship. 



There is one circumstance which may be mentioned respecting a ship 

 under steam, as to how she is affected by the direction and strength of the 

 wind. If a vessel be steaming before a fresh breeze, strength No. 8, at 

 the rate of 12 or 13 knots, she will experience a perfect calm, while the 

 sailing vessel will only be able to carry her top-gallant sails and royals. 

 If she steams in the teeth of the wind, she will seem to have a strong 

 gale, under which a sailing ship could only carry close-reefed topsails. 

 This will be made apparent by consulting the Tables of the Velocity of 

 the Wind on pages 105 — 106. Now, a vessel steaming with the wind 

 otherwise than directly fore or aft, will not feel the wind in its true direc- 

 tion ; for it will appear to blow from that direction and with that force which 

 is a combination of the rate and direction of the ship's course with that of 

 the velocity and direction of the wind itself. Its apparent and real course 

 and velocity may be found by constructing a parallelogram of forces — a 

 well-known problem. It is for this reason that the wind as registered oi 

 board a steam-vessel does not give the correct bearing of its course, and i 

 is much more disguised than it is in a sailing ship when close-hauled, a 

 alluded to in (14), on page 103. 



As the steam-vessel, then, may be considered in a great measure inde- 

 pendent of Wind and Current, the great object of the past and succeeding 

 remarks is mainly applicable to sailing vessels. 



(476.) It has been well observed that the Wind systems of our globe 

 naturally govern the tracks of ships crossing the Oceans, the Trade Winds 

 carrying them from East to West within the Tropics, while the Anti- 

 Trade or Passage Winds will bring them back again Eastward beyond the 

 Tropics. If it were not for the intervening Belt of Calms, sailing direc- 

 tions for vessels going into opposite hemispheres would be of the simplest 

 kind; but the well-known Equatorial embarrassments — " the Doldrums " 

 — generally make a very different matter of it, and cause many considera- 

 tions to enter into the problem of shaping a course. In the North Atlantic, 

 the obstacles of the intervening Calms seem to be at their maximum, and 

 in the future remarks one chief point, now still argued, will be found to 

 be that which has engaged attention almost ever since over-sea voyages 

 commenced — where is the best place to avoid these Calms and contrarieties 

 t)f the Equator. 



