MAP. 



according to their measured distances, 

 but without any mention of latitude, 

 longitude, or bearing. 



The maps published by Ptolemy of 

 Alexandria, A. D. 144, have meridians 

 and parallels, the better to define and 

 determine the situation of places, and are 

 great improvements on the construction 

 of maps : though Ptolemy himself owns 

 that his maps were copied from some 

 that were made by Marinas, Tirus, &c. 

 \vith the addition of improvements of his 

 own. But from his time till about the 

 14th century, during 1 which geography 

 and most sciences were neglected, no 

 new maps were published. Mercator 

 was the first of note among the moderns, 

 and next to him Ortelius, who undertook 

 to make a new set of maps, with the mo- 

 dern divisions of countries and names of 

 places ; for want of which, those of Ptole- 

 my were become almost useless. After 

 Mercator, many others published maps, 

 but for the most part they were mere 

 copies of his. Towards the middle of the 

 17th century, Bleau in Holland, and San- 

 son in France, published new sets of 

 maps, with many improvements from the 

 travellers of those times, which were af- 

 terwards copied, with little variation, by 

 the English, French, and Dutch; the best 

 of these being those of Vischer and De- 

 Witt. And later observations have fur- 

 nished us with still more accurate and co- 

 pious sets of maps. 



Maps are constructed by making a pro- 

 jection of the globe, either on the plane 

 "of some particular circle, or by the eye 

 placed in some particular point, according 

 to the rules of perspective. 



In maps three things are required : 

 first, to shew the latitude and longitude 

 of places, which is done by drawing a 

 certain number of meridians and parallels 

 of latitude. Secondly, the shape of the 

 countries must be exhibited as accurately 

 as possible, for real accuracy cannot be 

 obtained by any projection, because the 

 map is on a plane surface, whereas the 

 earth is globular. Thirdly, the bearings 

 of places, and their distances from each 

 othgi', must be shown. The projection 

 of maps is made, as we have observed, ac- 

 cording to the rules of perspective. If the 

 fye be supposed to view the earth from 

 an infinite distance, the appearance re- 

 presented on a plane, is called the ortho- 

 graphic projection. In this case, the 

 parts about the middle are very well re- 

 presented, but the extreme parts are 

 contracted. Geographers usually employ 

 the stereographic projection, where the 



eye is supposed to be on the surface ot 

 the Dearth, and looking at the opposite 

 hemisphere. There is likewise the globu- 

 lar projection, in which meridians, equi- 

 distant upon the surface of the earth, are 

 represented by equidistant circles in the 

 map. Mercator's projection is that in 

 which both the meridians and parallels of 

 latitude are represented by straight lines. 

 See GHAUT. 



In all maps the upper part is the north, 

 the lower the south, the right hand is 

 eastern, and the left hand western. On 

 the right and left the degrees of latitude 

 are marked ; and on the top and bottom 

 the degrees of longitude are marked. 

 When the meridians and parallels of lati- 

 tude are straight and parallel lines, the 

 latitude of a place is found by stretching 

 a thread over the place, so that it may 

 .cut the same degree of latitude on both 

 sides the map, and that degree is the la- 

 titude of the place. To find the longi- 

 tude, stretch a thread over the place, so 

 that it may cut the same degree of longi- 

 tude on the top and bottom, and that de- 

 gree is the longitude of the place. When 

 the meridians and parallels of latitude are 

 curve lines, then to find the latitude of a 

 place, a parallel line of latitude must be 

 drawn through it, by the same rules as 

 the other parallels are drawn, and it cuts 

 the sides at the degree of latitude of the 

 place : and to find the longitude of the 

 place, draw a circle of longitude through 

 it, by the same rules as the other circles 

 are drawn, and it cuts the top and bot- 

 tom at the degree of longitude of the 

 place. We shall now proceed to show 

 some of the most familiar constructions of 

 maps, beginning with a general map, or 

 map of the world, of which there are 

 three methods : 



First. A map of the world must repre- 

 sent two hemispheres ; and they must 

 both be drawn upon the plane of that cir- 

 cle which divides the two hemispheres. 

 The first way is to project each hemi- 

 sphere upon the plane of some particular 

 circle, by the rules of orthographic pro- 

 jection, forming two hemispheres, upon 

 one common base or circle. When the 

 plane of projection is that of a meridian, 

 the maps will be the east and west hemi- 

 spheres, the other meridians will be el- 

 lipses, and the parallel circles will be 

 right lines. Upon the plane of the equi- 

 noctial, the meridians will be right lines 

 crossing in the centre, which will repre- 

 present the pole, and the parallels of lati- 

 tude will be circles having that common 

 centre, and the maps will be the northern 



