492 The National Geographic Magazine 



breaks existed in the continuity of the 

 gold mining, which apparently was pro- 

 ceeding at or very shortly before the 

 Portuguese visit. 



After the recommencement of explo- 

 ration by sea in the fifteenth century, 

 seamen slowly gathered enough infor- 

 mation to draw the lines of the coasts 

 they passed along, and in time — that is, 

 by the middle of the eighteenth cen- 

 tury — most lands were shown with ap- 

 proximately their right shapes. But of 

 true accuracy there was none, for the 

 reason I have before mentioned, that 

 there was no exact method of obtaining 

 longitude. 



If we look at a general world chart of 

 A. D. 1755 — and to get the best of that 

 period we must consult a French chart — 

 we shall find on this small scale that the 

 shape of the continents is fairly repre- 

 sentative of the truth. But when we 

 examine details we soon see how crude 

 it all is. 



THE BEST CHARTS OF 1755, ON AN 

 AVERAGE, FORTY-EIGHT MILES 

 IN ERROR 



I have compared with their true posi- 

 tions the positions of thirty-one of what 

 may be taken as the fundamental points 

 in the world as given in the larger scaled 

 French charts of 1755, from which the 

 general one is drawn, and I find that on 

 an average they are forty-eight miles in 

 error. The errors vary from 160 miles 

 to 2 miles. If the delineation of the 

 coast lines between be considered, the 

 inaccuracies are very much greater. 



Very shortly after this date more ac- 

 curate determinations began to be made. 

 The method of lunar distances was per- 

 fected and facilitated by tables published 

 in the various astronomical " ephemer- 

 ides," and seamen and explorers com- 

 menced to make use of it. Still the ob- 

 servation required constant practice, and 

 the calculation, unless constantly made, 

 was laborious, and it was used with 

 complete success by the few. The great 



Captain Cook, who may be looked upon 

 as the father of modern methods of sur- 

 veying, did much to show the value of 

 this method ; but the chronometer came 

 into use shortly after, and the principal 

 advance in exact mapping was made by 

 its aid, as I have already stated. 



There is a vast amount yet to be done 

 for geography. Until we possess pub- 

 lications to which we can turn for full 

 information on all geographical aspects 

 of things on this globe of ours, there is 

 work to be done. Seeing that our pres- 

 ent publications are only now beginning 

 to be worthy of being considered trust- 

 worthy for the very small amount of 

 knowledge that we already possess, geo- 

 graphical work in all its branches is prac- 

 tically never-ending. 



VERY LITTLE OF EXPLORATION 

 REMAINS TO BE DONE 



But of exploration pure and simple 

 very little remains to be done. The 

 charm of traveling through and describ- 

 ing an entirely new country which may 

 be practically serviceable to civilized 

 man has been taken from us by our pre- 

 decessors, though limited regions still 

 remain in Central Asia and South Amer- 

 ica of which we know little in detail. 



I must except the Polar regions, which 

 are in a somewhat special category, as 

 their opening up affords few attractions 

 to many people. But a knowledge of 

 the past history of our globe — fit study 

 for human thought — can only be gained 

 by study of the portions still under 

 glacial conditions. 



What is there round the South Pole — 

 a continent or a group of large islands ? 

 What is going on there ? What thick- 

 ness does ice attain ? Have these regions 

 always been glaciated, and if not, why 

 not ? Can we get any nearer the mys- 

 tery of magnetism and its constant 

 changes by study at or near the mag- 

 netic poles ? All these and many other 

 scientific questions can only be solved 

 by general geographical research in 



