from L to the other end represented by P. But we already have point L and we will find point P by still holding the pencil horizontally, and we will see at what height this point is located compared to the tree. Once this height is found, we must find the distance from this point to the tree, again comparing this distance with the height of the tree. Here, the space between the tree's trunk and point P is equal to half the height of the tree. With point P found in both height and width, draw a line from the point represented by L to the point represented by P. Always, with the pencil horizontally, check if the tip of the roof represented by N appears higher or lower than the top of the tree. This point N is precisely at the height of point F, the top of the tree. Compare everything you see of the wall represented by ST with the entire width of the canvas or with the building's height. Again, compare the distance between the shore and the building's base with the building's height. Once the location and height of the building are found, also compare the width with the height. Draw as shown in the applications of plate 4, the glass (fig. 5), the bottle or steeple (fig. 10 and 18), the tower (fig. 13), etc.

To draw the building represented by ab; compare the distance between the first and the second building with the width of the first. The height and all dimensions of the second building are found by comparing them to the first. Other buildings and trees are also found by comparing all their dimensions with those of the first building. To find the various mountains located behind these buildings, several methods can be used: observing with the pencil whether the tallest mountain appears higher or lower than the building and tree, or by comparing, again with the pencil, the building's height with the highest point of the mountain. It is understood that the building beneath the highest point of the mountain is the comparison base. A tree, whose height has already been found, could serve as a means. It will always be through comparison that these different objects are found. The previous operations could also be made easier and quicker by the following means:

Once the painting is chosen and its width determined, if there is no tree, rock, or building nearby, one can start in the earth near oneself a stick three or four feet high, and find the different planes by leveling on this stick, as they were found on the window's side represented by the line JM of figure I.

The strip of paper mentioned on page 15 can also be used similarly. The different planes and building heights can be laid out on this paper.

By finding the places this way, draw the buildings as accurately as possible by always comparing small dimensions to large ones, following the method we have indicated. Trees require a particular study since place, height, and width are insufficient. Again, it is through comparison that larger masses are identified. A tree consists of several more or less regular circles: each mass describes a circle. If the tree is taller than the observer, each mass describes, for him, a circle viewed from below, like ab, figure 4. If, on the other hand, the observer is higher, each mass describes, for the observer, a circle seen from above, fig. 4 bis. The study of foliage requires some particular exercises. Attention should then be given to the objects that may be found at the water's edge.

Reflections in water.

Still water can be considered a mirror that faithfully returns the image of the objects reflecting in it; the water being a flat surface, the reflections are found horizontally. With still water, the reflection of an object placed at the water's edge is the same size as the object. These reflections are found as follows.

Translation Notes

- "porte-crayon" refers to holding a pencil or drawing instrument horizontally for measurement.

- "fig." is an abbreviation for "figure," often used in historic texts to refer to illustrations or diagrams in drawings or instructional material.