35 2 



The Realm of Nature 



tion, although much less distorted than the true cylindrical projection 

 of Fig. 66, is useless for comparing areas. But it is of unique value, 



;. 66. Cylindrical Projection. Lines drawn from 

 the centre of the globe through the parallels and 

 meridians are produced until they meet the surface 

 of the bounding cylinder, on which each parallel is 

 represented by an equal circle and each meridian 

 as a straight line. When the cylinder is unrolled 

 the mode in which the surface of the globe is 

 represented on the flat sheet is evident. 



because a line drawn between any two points cuts all the meridians 

 at the true angle, and it is therefore much used in navigation. 

 Plate III. and most of the other maps of the world shown are 

 drawn on Gall's stenographic projection, which does not distort the 

 areas so much, and does distort the angles considerably. Plate XII. 

 shows beautifully the amount of distortion of area in this projection, 

 the 250 mile coast belt appearing nearly three times as broad round 

 Greenland as round Africa where the distortion is least. In maps 

 of the world in hemispheres the meridians are shown converging to 

 the poles, and there is an infinite number of projections employed 

 for special purposes. Lambert's equivalent area projection (Plate 

 XIV.) is valuable because, although it distorts angles greatly, it pre- 

 serves the equality of areas ; a square inch measured on any part of 

 the map represents exactly the same number of square miles. The 

 calculations of Dr. John Murray, referred to in previous chapters, 

 were made by measuring areas on large-scale maps constructed on 

 this projection. Maps of a small area can be more accurately shown 



