The dimensions in which we represent such objects as houses, trees, roads, &c., in a topographical plan, depend, of course, upon the scale to which the drawing is made. Generally, for the sake of greater distinctness, they are enlarged to two or three times their proportionate size: unless the scale is very large, or when one of the objects of the plan is to exhibit every thing in its just proportion.

2. Explain the figures on the next page.

The figures in the first column explain themselves, in most cases, by some resemblance or appropriate sign; in other cases, they are purely conventional.

In Fig. 2, the signs of the plants are placed on the corners of squares drawn through the fields they occupy.

Fig. 3 shows the manner of expressing a pine forest with roads and the details of the leaves, in case the scale of the drawing will admit of their use. In forests, the trees are placed without any particular order or arrangement.

In Fig. 4, the horizontal lines, or the lines parallel to the top and bottom of the drawing, represent the watery portion of a fresh-water marsh: the rest of the figure, the earthy or grassy parts. In general, stagnant water is represented by horizontal lines; and meadow, or heath, by small tufts of grass. The combination of these two signs indicates morass, or wet ground.

Fig. 5 represents hillocks, or sloping ground. The paper is always left white to denote a level; and each one of the broken lines drawn from the summit to the base of a hill, indicates throughout its length the direction of the slope, or the line of greatest descent. The degree of blackness, or shade, produced by these lines shows the nature of the slope, from the perfect white of a level, to the deep blackness of an almost perpendicular descent.

3. Explain the figures on the next page.

Fig. 1 represents a rice-plantation; Fig. 2, an ornamental garden; Fig. 3, a cotton-field; Fig. 4, ploughed land; Fig. 5, an orchard; and Fig. 6, a vineyard. Figs. 1, 3, 5, and 6, are drawn as was described in the case of page 65, Fig. 2. Where it is not necessary to describe minutely the kind of crop existing upon the land, every kind of cultivation may be expressed as is done in Fig. 4.

Figs. 7, 8, and 9 indicate, respectively, the details of the leaves for oak, fruit, and chestnut trees, whenever their use in a plan is desirable.

Fig. 10 represents a heath and common road. It is left white, being a level, with the exception of the tufts of grass.

Fig. 11 is an oak, &c. forest.

Fig. 12 is a salt marsh. This is drawn in a different manner from a fresh-water marsh, being composed of unbroken horizontal lines, with tufts of grass interspersed among them.

Fig. 13 represents meadow, or bottom land, with a small stream running through it. The sign for the grass is here more regularly disposed than in a heath, or common.

Fig. 14 shows the mode of indicating different kinds of roads, fences, paths, &c.

4. How is water represented?

Running water, the water of lakes, and water that is affected by tides, are always represented by lines drawn within the outline, and parallel to the shores, in such a manner, that by gradually increasing the distance between the lines, which are at first very close together, the shade may be uniformly lightened from the shores to the middle. The course of the current is indicated by an arrow, with the head turned in the direction in which the water runs.

5. Explain the figures on the next page.

Fig. 1 represents the rocky shore of water thus shaded.

Fig. 2 denotes rocks that are above the surface of the water. Here, also, the lines indicate the direction of the descent from the highest point, near the middle, to the water line.

Fig. 3 shows the manner of representing salt-works. Figs. 4, 5, and 6 show the three conditions of sand-shoals. Fig. 7 is a sign used to show the direction of the current. Fig. 8 shows that there is no current.

Fig. 9 indicates the different stages of the tides by means of dots introduced in all shading above low-water mark.

Fig. 10 represents rocks sometimes bare, and Fig. 11, sunken rocks.

Fig. 12 is a shore with sand-hillocks and fisheries.

Fig. 13 is a collection of signs used for describing the facilities or dangers of navigation.

Fig. 14 exhibits a river, with the different circumstances connected with its navigation, and the means of crossing it. Fig. 15 is a lake, shaded in the manner before described.

In shading a piece of water by this method, this rule must be observed. Having drawn the outline, conduct the first shading line along every shore, (if there be more than one,) and around all islands, keeping it as close as possible to the shore-line.

When the first shading line is thus applied everywhere, take up the second one, laying it nearly as close to the first as the first is to the outline. When the second line is drawn wherever it can go, take up the third; increasing gradually and uniformly the distance between the lines, un