1830.] 
of Shading Mountain Land. 
55 
of ink and 9 of water, in the next 2 of ink and S of water ; then 3 and 7, 4 and 6, and 
so on till we come to 9 of ink and 1 of water, being the next to the pure black shade; 
then these 9 tints will represent the following inclinations 
No. 
Ink. 
Water. 
Angle of Inclination. 
1 
1 
9 
25°. 
9 
51' 
2 
2 
8 
36. 
53 
3 
3 
7 
45. 
34 
4 
4 
6 
53. 
03 
5 
5 
5 
60. 
00 
6 
(5 
4 
66. 
25 
7 
7 
3 
72. 
33 
8 
8 
2 
78. 
28 
9 
9 
1 
84. 
15 
To apply these tints in the method of shading by hatches, is more difficult. If we 
assume that the thickest line which can be admitted is about ^ of an inch, and 
conversely the broadest space, then we shall have the following scale : 
Angle of Inclination. 
B readth 
of Line. 
Breadth of Space. 
25. 51 
36. 53 
45. 31 
53. 08 
60. 00 
66. 25 
72. 33 
78. 2 
84. 15 
Inch. 
,002 
,004 
,006 
,008 
,01 
,012 
,014 
,016 
,019 
Inch. 
1 
5 O 5 
23<y 
i 
1G6 
1 
72 5 
1 
Too 
1*5 
71 
l 
36 
1 
5 5 
,018 
,016 
,014 
,012 
,01 
,008 
,006 
,004 
,002 
I 
53 
i 
6 6 
1 
7i 
l 
83 
} 
10 0 
1 
12 5 
1 
16e 
1 
50 0 
It must be confessed that the principle of this method is excellent, in as much as 
it affords a definite scale by which to measure the inclination of the surface. In 
practice it is said to be not difficult, and to he capable of representing with won- 
derful detail and certainty every the minutest undulation of the ground. But we 
may easily perceive that this eulogium is to be understood cum grano salts. For 
it appears perfectly hopeless ever so to apportion the thickness of the lines and 
spaces, as to represent with any thing like fidelity the actual inclination of each sur- 
face. If then it he found so easy in practice, it must evidently be from this fidelity 
being disregarded in a certain degree. In fact, it is not pretended that the inclina- 
tion of every surface is actually determined, and also tbe depth of shade by which 
that inclination should be expressed ; but rather that, having fixed a few positions by 
which the outline of the feature is obtained, the eye is depended on for an estimate 
of the slopes, as well as for the depth of shade necessary to represent them. Prac- 
tice will give great facility, there is little doubt, in these operations ; still there can 
be no question that the eye will often make mistakes, for it is proved that nothing is 
so deceptive to the spectator, or so difficult to judge of with accuracy, as an inclined 
surface. 
But as these objections apply equally to what may be called the pictorial repre- 
sentation of ground, there can be no question of the preference due to the former 
over the latter. When most loosely executed, it represents equally precise informa- 
tion, and in a character which is not only easily read, but which is definite to a de- 
gree exceeding that of the information to be conveyed. It is, at the same time, ca- 
pable of representing, with perfect accuracy, all that can with any degree of trouble 
be ascertained, so that it will always keep pace with observation. No particulars 
collected need be lost for want of means to represent them. The pictorial method 
has none of these claims on our attention. It is, in fact, only fit for those who con- 
sider a map as rather meant to please the eye than to satisfy the judgment. When 
