1830 .] 
of Shading Mountain Land. 
57 
jections to which they are liable. The following are what appear to me to be ob- 
jections to that which is, in my opinion, the preferable of the two. 
The German method applies itself to represent surfaces, expressing, by the depth 
of shade used, the inclination of that surface to the horizon. This is always an im- 
portant feature in the delineation of ground ;and to obtain accurate information on 
this subject, is certainly, at least to military men, a principal object in consulting a 
map ; I mean a topographical one. The knowledge of the acclivities in a mountain- 
ous country naturally lead us to infer the relative heights of the different posi- 
tions ; so that in a map executed in this manner, the person who consults it may, 
with a little consideration, satisfy himself of the relative height of every point in it. 
It must, however, be acknowledged that these particulars are not forced on our no- 
tice: it requires, as I said, some attention to discover them, and what is of more con- 
sequence, it is only the relative heights that can be thus known. When we look at 
a map of this kind we do not immediately perceive which is the high ground and 
which the low, but with a little attention these particulars become visible. No at- 
tention, however, will enable us to say how high any point is. Yet, information of 
this kind is often required in a map, and there is little question that were they ca- 
pable, in general, of conveying such information, their utility would be very greatly 
increased. I may add, that the German method is incapable of expressing those de- 
licate undulations and differences of level which are often to the engineer the most 
important of all. These are certainly exceptions to our unqualified admiration of 
the method, and it must, in fact, be acknowledged, that it is no more capable than 
the other of representing, in a generally intelligible manner, all three co- 
ordinates of any point ou the surface of the earth. 
It may be replied by the advocates of the method, that as the slope of every part 
of the ground is expressed, and also the horizontal projection, a combination of 
these elements should, by calculation, enable us to fix the absolute height of any 
point in the map. But besides that, this would be an enquiry into which an ordi- 
nary consulter of the map could not be expected to enter ; it would be so great a la- 
bour, that, 1 can confidently affirm, no one would, however qualified, engage in it. 
And besides this labour, there is the further objection, that it is not possible any 
map could ever be executed on this principle with such accuracy as to enable it to 
be applied to such a use. If the map could express the heights accurately, the slopes 
would be almost obvious to the eye, and could, with a very trifling application of 
thought, he conceived with the utmost accuracy ; but the reverse of this is so far 
from being true, that it is, I will venture to say, scarcely possible. 
lo these objections may be added, that a method which employs shading to ex- 
press inclination of surface must have the effect of rendering a map of a mountain- 
ous country such a map of shade, that no other particulars will be sufficiently vi- 
sible. Nothing is commoner than to bear complaints on this head against such 
productions. Not only are all the other features of the ground, in topographical 
e mention, concealed, but villages and towns, with their names, and sometimes 
even the rivers, where the hatching is very deep. In such a map you cannot dis- 
tinguish whether a mountain be bare or covered with forest, cultivated, or a barren 
waste ; water-courses are dried up, and wells or springs are looked for in vain • while 
any information to be conveyed in writing is altogether lost. Nor is such system 
of shading much better for geographical maps. In fact, it is evident, that in adopt- 
ing shade as the expression of any general feature of a country, we lose the principal 
advantage of exhibiting clearly to the eye the other particulars; many of which are 
equa y valuable. It is as though we used a dark papeF on which to draw our map 
In the case of a geological map, the one, perhaps, in which the expression of the 
arrangement of the surface is most valuable, the method is altogether inapplicable 
on account of interfering with the colours employed to represent certain rocks. ’ 
I icse objections, which are not made in a spirit of cavilling, certainly take from 
* ZZT 0t m r te ?Y In 5°" siderin S « force, I have been So enquire 
<- >ei a method could not be found that should represent accurately the level 
ftlZ tj ie S . ea 01 every point , in ? ie ma P’ which > could it be done in a manner S0 as to 
■ . ie ej e at once, would also be capable of communicating all the other par 
7^° “ Ztn°" reqU , ired * ,eras rJ of * ™P 0f a "-.flinous county 
* t o in crude T V " e satlsfied ™P eIf on the sull i«t, but an account if 
1 10 a future opportunity^ 
D. 
