MOUNTAINS. 



MOUNTAINS. 



188. Maps, and Globes in Relief. Elementary instruction in 

 geography has been hitherto for the most part limited to the 

 description of the outlines of land and water. The varieties 

 of form depending on relief have been comparatively neglected. 

 This has arisen most probably from the difficulty of presenting to 

 the student visible representations of such forms. Maps and 

 globes, showing in moulded relief the inequalities of the land, 

 have indeed been constructed, and with suitable explanations may 

 be found useful to the teacher and the pupil. Independently, 

 however, of their cost, which is necessarily considerable, they are 

 subject to grave objection, owing to the enormous violation of 

 proportion between the vertical and the horizontal dimensions, 

 which they must necessarily exhibit. It has been explained else- 

 where, that the elevation of the most lofty mountain-summits does 

 not exceed the 1600th part of the Earth's diameter, and conse- 

 quently such a summit, if formed in relief in its just proportion 

 on a 16-inch globe, would be represented by a protuberance not 

 exceeding the hundredth part of an inch. All maps and globes, 

 therefore, presenting the inequalities of the land in moulded 

 relief, must, in order to render them perceptible at all, give the 

 vertical magnitude exorbitantly disproportionate to the horizontal 

 dimensions. When such illustrations are used for the purpose of 

 elementary instruction, the teacher should be careful to impress 

 upon the mind of the pupil this inevitable departure from the 

 natural proportions. 



189. Johnston's Physical Maps. The expedient adopted in 

 the physical maps of Mr. A. K. Johnston renders them exempt from 

 this objection, although the same vivid illustration of the super- 

 ficial inequalities is not presented by them. In these the plains, 

 valleys, and lowlands are coloured green, the elevated plateaux 

 and table-lands brown ; and the mountain-ridges and peaks are 

 distinguished by obvious marks indicative of their relative alti- 

 tudes, the actual heights being marked in numbers of English 

 feet. The sea is also everywhere distinguished from the land by 

 its blue colour. As a physical illustration, these maps are there- 

 fore, as I conceive, as perfect as the nature of the subject of 

 instruction allows. 



190. Mountam^ranges not uniform. Although each of the 

 great oontinenta_ systems, which have been already described, is 

 characterised by a certain prevailing direction, it must not be sup- 

 posed that it follows one uniform and unbroken course, or even 

 that it consists of a single uninterrupted series. They are, oil 



185 



