The term " windward great-circle sailing " is employed with special 

 reference to these facts. This new form of describing the application 

 of the true course is rendered necessarj' on account of the prevalent 

 erroneous opinion — that " to a sailing vessel gi'eat circle sailing is of 

 comparatively little value ;" and that " steamers, being in a measure 

 independent of the winds, could more readily than sailing vessels avail 

 themselves of the advantages of great circle sailing." The reverse is 

 the fact : to a saihng vessel, the advantage of being guided by the true 

 course, when contending with adverse winds, is fourfold as great as that 

 which is conferred on a steamer. Thus, for example, the increase of 

 distance arising from the direct track being diverted two points is only 

 1 mile in 12 : but if a ship that sails six points from the wind deviate 

 two points further from the angle of the true position of her port on 

 account of the wrong tack being chosen, she cannot in the least 

 degree near her port ; whilst, under the same circumstances, the know- 

 ledge of the true course would enable the mariner so to choose his 

 track as to make good 8^ mUes by a run of 12 miles. 



The rule for windward great circle sailing is as follows : — Ascertain 

 the great circle course, and put the ship on that tack wliich is the 

 nearest to the great circle coui'se. 



We can give no better illustration of an extreme case of this applica- 

 tion of gi'eat circle saihng than that already given of the " Marco Polo" 

 leaving Melbourne. Had that sliip stood on the port tack 1000 miles, 

 with the -wind S.E. by E. she would have neared the Horn 874 miles ; 

 whereas, if the " Kent" had stood 1000 miles on the starboard tack, she 

 would have been 200 miles further off from the Horn than when she 

 started, although by the chart the reverse appears to be the case. To 

 make use of the words of the Hydrographer in reference to this subject, 

 this principle is valuable "not only in those strong and glaring cases 

 where a large amount of distance may be obviously saved, but in the 

 more everyday work of selecting the most advantageous tack on which 

 to lay the vessel with a foul wind." Scarcely have I examined a chart 

 or a log-book without perceiving that this is not perfectly understood. 

 I am frequently informed that they could not get so far south as their 

 intended maximum latitude. Now this is an impossible occurrence 

 with a ship of ordinary weatherly qualities. If the wind be less southerly 

 than E.S.E., she would undoubtedly do better on the port tack till 

 she got into the regions of the N.W. trades ; if more southerly, she 

 could make easterly on the starboard tack. 



In a New York voyage, if head winds prevailed, I proved seven years 

 since that three days might be saved ; and yet I have no reason to 



