3830 .] 
of Shading Mountain Land, 
53 
surface, the places AB will ho 
represented in a map at a. b , but 
it is evident that the distance of 
the points a b gives a very 
inadequate idea of the distance 
A B. 
This difficulty, which involves 
the representation of all the in- 
equalities of the proposed portion 
of the earth’s surface, and con- 
sequently the features of a moun- 
tainous country, has been variously got over. In the very old maps a congregation 
of conventional signs, each intended to represent a mountain, was introduced and 
arranged so as to give some idea of the direction in which the mountain land was 
disposed. Those who have seen maps executed on this principle, will acknow- 
ledge how very imperfect is the information it gives of the inequalities of the 
ground, either as to arrangement and connection, or elevation above the general 
plateau of the country. Rude as the method is, and destitute of precise meaning, 
I have known many who affected to prefer it to the modern method of deep hatch - 
ing, which they assert has the effect of rendering a map illegible without being a 
whit more precise. There is some grouud, it must be confessed, for forming this 
opinion— at least if we confine ourselves to English maps ; but those executed on 
the continent do not deserve this censure. Arrowsmith’s Map of India is a 
splendid example of this cheatery of the eye. To form any thing like a correct 
idea of the surface of India from his map, thickly as it is covered in parts with 
these “ caterpillars,” as I have heard them called, is impossible. Very often it 
will he found that what the peruser of the map supposes is a high ridge, is in real- 
ity a low one, and vice versa; while vallies are elevated into ridges, and these again 
sunk to vallies. A certain quantity of ink has been applied to the paper, but to 
what purpose, save that of blackening it, it would puzzle (Edipus himself to say. 
Nor are the maps of other publishers much better, and, still more extraordinary, 
I fear, that even to many manuscript maps executed in this country, much of 
this censure must attach. 
The map-makers on the continent have higher ideas of their art, and do not trust 
so important a feature of their work to an ignorant draughtsman, who knows no 
more of the principles which should guide him in the representation of ground, 
than the brush, by the aid of which he annually destroys so much paper. It is 
evident that a map, to be any thing, ought to be precise ; it is otherwise worse than 
useless. To represent hills where there should be vallies, and vallies where there 
should be hills ; or to give an erroneous idea of the comparative heights of different 
points above the general level, is to take from the map all the value it could ever have ; 
and it would be much better and less troublesome, not to attempt at all the delinea- 
tion of the surface features, than to represent them erroneously, inasmuch as ig- 
norance is preferable to error. 
“ They manage these things better in France,” as I before observed, and in Ger- 
many too. Some of the continental maps are quite curiosities in this respect; I mean 
considered with regard to the accuracy of representation with which mountain ground 
is delineated. On the continent they always consider it necessary to determine the 
three co-ordinates of every position, but we are satisfied with two ; and indeed much 
of the foregoing censure is applicable as much to the geodest or surveyor, as to the 
draughtsman. The latter cannot frame a representation, the data of which are want- 
ing, and he is, therefore, often compelled to draw on his imagination. It is no won- 
der then if we occasionally see such grotesque productions. 
Supposing all three co-ordinates known in any given portion of a country, it may 
he asked, how can more than two of them be inserted in a map which is a plane sur- 
face, and, consequently, can have but two dimensions, length and breadth ? To this it 
may be answered, by a similar artifice to that employed in a picture, in which ob- 
jects of three dimensions are represented on a plane, and with such effect as to ena- 
ble the eye to judge with considerable accuracy of figure and proportion : by au 
application of the principles of light and shade, it is possible to give to a plane sur- 
face, all the appearance of projections of various heights; nor is the application of co- 
lour necessary to obtain perfect distinctness, as far as mere figure and situation are 
concerned. The map, in fact, becomes a perspective representation of the country, 
the eye being supposed at an indefinite distance. 
