426 HOW MAPS AIJE MADE. 



Tliougli I liave ii<» direct evidence to sliow how Mercator argued out 

 lii.s system, I liave not the least doubt that it was somewhat thus: 



Mercator was a globe-maker, and no doubt worked from the globe. 

 He stripped his gores off the globe, forjning a map like this (Plate xxi, 

 fig. 1), wliicli was naturally very inconvenient, owing to the hiatuses 

 between the meridians. ITe was obliged to join the gores along their 

 meridians (Plate xxi, tig. 2). He then found that he had distorted every- 

 thing, and the distortion increased in the higher latitudes, owing to the 

 gores being further apart towards the top of the map. In order to 

 restore a balance of orientation (or the relative position and direction 

 of places), as he had distorted in longitude, so lie had exactly in pro- 

 portion to distort in latitude, as shown in Plate xxi, fig. 3, a complete 

 Mereator's map of half the Northern Hemisphere, in which you Avill 

 observe that the jiarallels are farther and farther apart as the latitude 

 gets higher. / 



As these gores are not a familiar shape, I have a square here which 

 will catch the eye at once (Plate xxi, fig. 1^/). I distort it first by pull- 

 ing it out horizontally as Mercator did in joining the meridians, and 

 it ceases to be a square and the orientation is changed (Plate xxi, fig. 

 2a). I then distort it in height in the same proportion, and it becomes 

 once more asquare with tlie true orientation but larger than the original 

 square (Plate xxi, tig. 3a). This is exactly what we did before with the 

 gores of the globe. 



Every parallel, in Mereator's projection, is a straight line, and every 

 meridian is also a straight line. We have, th«Mj, an excellent sailing 

 line from point to point. As Sir George Grove puts it very neatly 

 (though he shirks the explanation of the iH'OJection), " The most ignor- 

 ant sailor can lay down his course without calculation. In fact, the 

 invention of this map has been justly called one of the most remarka- 

 ble and useful events of the sixteenth century; because it enables com- 

 mon, unlearned peoi)le to do easily and correctly what only clever, 

 learned people could have done without it." 



Mereator's j)ro)ection is that used in all nautical charts to this day, 

 because to the sailor it is far more important to know his direction or 

 course than his distance, which with ordinary nautical knowledge, or 

 from nautical tables made for him, he can easily calculate, but he needs 

 to see his course. 



In the conical projection (Plate xxii, fig. o) we imagine a cone of paper 

 to be rolled round tlie globe, touching it on the middle line of the map. 

 jSTear their line of contact the map coincides very nearly with the globe 

 surface, and is fairly accurate; but as it gets farther away from the 

 touching point the distortion grows, the places being shown larger than 

 in reality. For comparatively small areas, such as for maps of p]ng- 

 land and France, it is fairly accurate, aiul is the i)r(>jection used in 

 atlases. 



In the illustrations (Plates xxi, xxii) we see the same globe projected 



