of the advantage of such knowledge, if ignorant of the principles of great 

 circle sailing. Where is the mariner, whose knowledge of this earth is 

 derived from a chart of Mercator's projection, who would ever think of 

 sailing to the southward so high as the 54th parallel, in order to reach 

 the Chincha Islands ? For the sake of favourable winds, the passage 

 through Cook's Strait was proposed, but never would it have been 

 suggested to enter the regions of the westerly trades, except by one who 

 understood the principles of great circle sailing. 



But I will now refer to another example, to prove the necessity of a 

 knowledge of this earth as a globe, in order to avail ourselves practically 

 of any acquaintance with the nature of the winds that prevail in various 

 regions of the ocean. Great circle sailing does not effect so much 

 saving of distance under some circumstances as under others. If we 

 have the equator between the ship and her port, a considerable saving 

 in distance cannot be effected : thus, in a voyage between Panama and 

 Australia, the difference between Mercator's track and the great circle 

 route is only 170 miles, if it were practical. But New Zealand comes 

 in the great circle track, so that there are three routes from which the 

 mariner can make his choice, neither differing more than 100 miles 

 from the other ; they are the rhumb, or Mercator's track, the great 

 circle route by the north of New Zealand, and the great circle by the 

 south of New Zealand. These routes, separate from each other 2,000 

 miles and upwards, have winds of a very different character prevailing. 

 I was consulted as to the best route a steamer might take in saiUng 

 from Panama to Australia and back. Had I known no more of the 

 earth's surface than that which I derived from Mercator's chart, I 

 should have had the difficult problem to solve of balancing winds 

 against distance. But the knowledge of the earth's true surface made 

 the question easy of solution. I find by the south of New Zealand 

 the most favourable winds that blow for a voyage from Australia to 

 Panama. From Panama to Australia, by the great circle, north of 

 New Zealand, we get as favourable winds as by the rhumb track ; and, 

 although we save only 70 miles of distance, we avoid the innumerable 

 dangers which lie in the Mercator's track, in which we should have 

 been entangled in the Low Archipelago, in Dangerous Archipelago — 

 ominous name — amongst coral reefs without number, atolls, lagoon 

 islands, innumerable rocks, and unknown islands. This perhaps forms 

 the most striking illustration of the value of great circle sailing, in 

 giving us the choice of more than one route. (See plate No. \.) 



There was, however, one objection that existed some years since to 

 the value of great circle sailing. It was said that, unless the distance 



