Читать книгу Geography For Dummies - Jerry T. Mitchell - Страница 101

The area shown on a map is a fraction of its actual size. Appropriately, therefore, scale may be indicated as a representative fraction (RF), which states the ratio between a unit of distance on the map and the same distance measured in the same units on the ground. As far as most people are concerned, this is the most confusing scale-type and the most difficult to explain. OK, here goes.

Check out Figure 5-1 again. The RF shown is 1:63,360. That means the map is 1/63,360th the size of the area it shows. Stated differently, a distance of one inch on the map equals 63,360 inches on the Earth’s surface.

Once more, a given map has a given scale, but you can express it in different ways. In the example, therefore, “One inch equals one mile” and “1:63,360” must mean the same thing. And, indeed, they do. Proof is obtained by calculating the number of inches in a mile. To do that, multiply the number of inches per foot times the number of feet per mile (12 × 5,280). The answer is 63,360, so the statement of scale and the RF are, in fact, the same.