202 



♦ KNO\ArLEDGE 



[July 1, 1887. 



stereogi'aphic chart, whore the same letters are used as in 

 Figs. 3 and i. 



[By a singular coincidence the distance actually determined 

 by my construction for the gi-eat circle course from Cape 

 Town to Melbourne was 5,567 miles, the nearest result in 

 whole numbers to the distance determined by calculation, 

 viz., 5,566f miles. But having obtained the angle 92° 47', 

 I did not consider anything closer than 92|° could fairly be 

 used, giving the distance 5,565 miles (very close for a deter- 

 mination of this sort). 



Tlie distance between Cape Town and Melbourne on a 

 rhumb course is 6,154 miles, or 587 miles lomjer than the 

 great circk course /] 



The illustrative chart shows, on a small scale, my northern 

 chart on the plan described. It has been carefully drawn, 

 with meridians and parallels ten degrees apart correctly 

 placed. The distortion is great outside the equator, but 

 not greater than for high latitudes in Mercator's chart; 

 nor does distortion at all affect the utility of such charts. 

 (The stereographic and Mercator's projections are alike in 

 showing small regions with little distortion.) More than 

 thirty great circle-paths are shown, but of course the charts 

 which I have had prepai'ed for sailors' use (under Mr. E. 

 Stanford's supervision) are without paths of this sort, the 

 object of the charts being to enable the seaman to lay down 

 without trouble the track he has to pursue in order to tra- 

 verse the shortest distance from any port whatever, or from 

 any point he may have reached on his journey, to any 

 haven. 



The north pole being in this chart the centre of projection, 

 the northern regions are on a relatively small scale. Thus, 

 the few great circle tracks shown on the Atlantic are not so 

 well presented as the tracks in the southern seas, or from 

 the northern to the southern hemisphere. The meridians 

 and parallels of the chart serve, however, equally well for a 

 map of which the south pole would be the centre. I have 

 had a second chart prepared on this plan (the distortion 

 affects Asia and North America very curiously), and the 

 smaller map (a quarter of the chart) shows the North 

 Atlantic as presented in this chart, the projection and scale 

 being the same as for the larger chart. Although my laige 

 northern chart would suffice without any supplementary 

 southern chart, yet the southern scale adds greatly to the 

 completeness of the work. Moreover, by applying rule I. 

 for pencilling the course on both charts, and comparing the 

 results (which ought to agree, of course, exactly) the seaman 

 will escape all possibility of any error, however slight, 

 and will find his confidence in the accuracy of the method 

 strengthened, should he, by chance, be unable to understand 

 the mathematical reasoning on which the method is ba-sed. 



THE VOYAGES OF COLUMBUS CHARTED. 



By Richard A. Proctor. 



|0 illustrate at once the convenience of the 

 one-scale maps now appearing monthly in 

 Knowledge, and the advantage of great- 

 circle routes across the ocean, 1 give a map 

 (No. 1) on the same projection in which the 

 routes followed by Columbus across the 

 Atl.intic have been laid down for com- 

 parison with the corresponding great circle I'outes. The 

 map also shows th3 shortest routes between several places 

 in Europe and America, together with the rhumb coiu'se 

 between Queenstown and New York (the course indicated 

 as the shortest in Mercator's charts, but really not so). 

 On Friday, August 3, 1492, Columbus, in command of a 



squadron consisting of the Santa Maria (a decked vessel) 

 and his flag ship, the Pinta, and the Xina, set sail from 

 Huelva on his first journey across the Atlantic in search of 

 a westerly route to " far Cathay." In the same year a globe 

 was made at Nuremberg, from which the accompanying map 

 (No. II.) has been formed. By compai-ing it with map I., 

 which is in fact a chart of the North Atlantic, some notion 

 can be formed of the ideas which were entertained by the 

 most experienced geographers in the days of Columbus 

 about the unknown Western Seas. About as far west from 

 Europe as the shores of the United States really lie, we 

 find Cathay, a small island, and Cipangu, a larger one, 

 doing duty, but most inefliciently, .and far from their proper 

 latitudes, for China and Japan. What island it may be, to 

 which Sieur Brandan came in the year 565, it would be 

 difficult to detei'mine ; but neither Behem nor anyone else 

 in those days had clear notions about the distances traversed 

 by voyagers who reported shores they had sighted. How- 

 ever, this island was reported to have been seen by tra- 

 vellers sailing south-west from the Cape Verde Islands, and 

 is therefore probably altogether mythical. 



On August 9 Columbus sighted the Canaries. It was not, 

 however, till September 6 that the squadron sailed from 

 Gomera, nor till Sunday, September 9, that the heights of 

 Ferro, the most westward of the Canaries, faded from view. 

 On September 13, about six hundred miles due west of 

 Ferro, Columbus noticed the variation of the needle, five or 

 .six degrees eastwards of true north,* a deviation which in- 

 creased as he proceeded. 



On September 14 the voyagers saw a heron and a tropical 

 bird which they regarded as harbingers of land ; but, on the 

 following night, they were alarmed bj' a meteor, which they 

 held to be ominous. Columbus explained the meteor 

 after the simple manner of his time, when science under- 

 stood everything ; Irving, however, condescendingly remarks 

 that these objects are common in warm climates, a statement 

 about as instructive as though he had said that planets are 

 peculiar to the subtropical skies. On September 20 the 

 wind, hitherto from the east, veered to the south-west, and 

 they altered their course (when in about 40° west longitude) 

 slightly northwards. Sever.al birds, regarded as denizens of 

 the land, visited the ships, and next day the squadron reached 

 the Sargasso, or great seaweed bed, which they endeavoured 

 to avoid. On the 25th the wind again became favoui'able, 

 and for several days thereafter they sailed steadily south- 

 westwards, taking an almost due westerly course on Sep- 

 tember 30. On October 6 Martin Pinzon, commander of 

 the Pinta, proposed that they should stand more to the 

 southward, and in the evening of October 7 Columbus 

 altered the course very slightly southwards, being then in 

 about west longitude 65° from Greenwich. For three days 

 they stood in this direction, the signs of land becoming 

 more and more frequent. The crews, however, regarded 

 these signs as meant to lure them to destruction ; and 

 Columbus, who had hitherto kept his men in good spirits 

 by gentle words and promises of reward, was compelled for 

 the first time to adopt a sterner demeanour. This was on 

 Wednesday, October 10. On the 11th the signs of land 

 became unmistakable. It was at about ten, on the night of 

 Thursday, October 11, that Columbus saw a light glimmer- 

 ing at a great distance, wliich he showed to Pedro Guiterrez, 

 " gentleman of the king's bedchambei-," whatever dignity 



* Washington Irving says the needle pointed to the north-west, 

 but that is wrong : what Columbus found was that the true north lay 

 to the west of the point indicated as north by the magnetic needle ; 

 probably Irving was misled by the circumstance that now the 

 needle points west of north at the place where Columbus first dis- 

 covered its deviation. The magnetic pole was considerably east of 

 the latitude of Greenwich in the year 1492. 



