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tances from 1 to 2, 1 to 3, 4, 5, and 6; and through 2, 3,

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and 6 draw perpendiculars, which being met by parallels through d, r, and R, will determine all the parts of the cottage. The two heights aw, aw, to the bottom and top of the window, are not found in the section, but are taken from the oblique elevation.

29. After finishing an elevation, or other geometrical drawing, the superfluous or dotted lines representing planes of projection, scales of heights, &c., are rubbed out; excepting only those imaginary lines, marked in the plan, which show the direction according to which the sections or oblique elevations accompanying the plan may have been taken.

Let us, therefore, rub out the superfluous lines, letters, &c., in the figures which have been drawn, leaving only such as are necessary to explain the connection between the plan and section, and between the plan and oblique elevation. We shall then have

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Front Elevation.

Oblique Elevation.

The Plan, Section, and Elevation, completed above, are sufficient to give a full insight into the principles of plan drawing.

GENERAL REMARKS.

30. All plans, sections, and elevations are drawn by laying down a certain number of points and lines truly, on some plane surface, according to geometrical principles. In drawing some objects, it may be necessary to lay down a great number of points and lines: in others, only a few; but whether the number be great or small, each individual point or line must be drawn, in all cases, according to some one or other of the foregoing rules.

Plans which, as before stated, resemble the appearance of any object viewed from a height directly above it, do not carry a very just notion of the object to persons ignorant of the principles of plan drawing; because opportunities of looking perpendicularly or directly down upon objects are

not common.

Ground plans, or foundation plans of buildings or other works, do not give any just notion of the appearance of the object represented; because when a building is finished, it is impossible, from any point of view whatever, to see the various walls and foundations, in the manner in which they must be represented in the ground plan, the whole of these parts being hidden by the roof. In fact, the ground

plan of any finished building is, properly speaking, a horizontal section through the various walls-the only difference between it and the common section consisting in this, that the common section is taken vertically, whereas the section which exhibits the ground plan is taken horizontally.

31. In plans, sections, and elevations of any object, when the various points and lines have been laid down according to the rules of projection, it is usual afterwards to color or shade the figure in order to make a finished drawing.

The art of plan drawing, therefore, comprehends two distinct operations: first, the projection of the lines which form the representation of the object; and secondly, the shading or coloring of it.

In colored plans and sections, masonry is generally made red; wood so as to represent its own natural color; earth of a sandy color; iron of a dark blue; and water of a lightish blue.

In plans not colored, masonry is generally made dark, while wood and other substances are made lighter.

In sections not colored, different substances are shaded darker or lighter, according to the fancy of the draughtsman.

In plans of buildings, the doors and windows are left blank, while the walls are either colored or shaded. And in sections, a marked distinction of color or shade is also made between the solid part of the walls, and the doors, windows, or other apertures which may be represented.

In elevations of any object, whether colored or not, the various parts are shaded in such a manner as to resemble, as much as possible, the outward appearance of the object.

BOOK IV.

SECTION I.

OF ARCHITECTURE.

1. What is Architecture?

Architecture is the art of construction.

2. Into how many branches is it divided?

Into three principal parts:

1st. Civil architecture, which embraces the construction of public and private edifices.

2d. Naval architecture, which embraces the construction of vessels, ports, artificial harbors, &c.; and

3d. Military architecture, which embraces the construction of forts, redoubts, and all military defences. We shall speak here only of civil architecture.

3. What are the elements of architecture? They are the MOULDINGS.

4. What are mouldings?

They are the projecting parts which serve to ornament architecture.

5. How many kinds of mouldings are there?

Three kinds those bounded by planes; those bounded by curved surfaces; and those bounded by both plane and

curved surfaces.

6. What are the principal plane mouldings?

They are the Fillet, the Drip, and the Plate-band.

7. What is a fillet?

It is a square moulding which projects over a distance equal to its height.

8. What is a drip?

It is a large projecting moulding, hollowed on the under side, and placed in cornices to protect the edifice from rain

9. What is a plate-band?

It is a large and flat moulding which projects but little.

10. What are the principal circular mouldings?

The Ovolo, the bead or Astragal, the Torus, the Cavetto, the Scotia, the Cyma-recta, the Cyma-reversa, and the Ogee.

11. What is an Ovolo, and how do you trace it?

An ovolo is a moulding flat on the top and bottom, and whose circular projection is equal to its height.

To describe it, make the perpendicular height AD equal to the projection AC: then, with A as a centre, describe the arc DC. If you wish to make a flattened ovolo, with B as a centre and BA as radius, describe an arc: then, with A as a centre and AB as a radius, describe a second arc, meeting the first in C. Then, with C as a centre, describe the arc BA.

12. What is the Bead or Astragal, and how is it traced? It is a thin moulding, of which the circular projection is equal to half the height. To trace it, describe a semi-circumference, of which the diameter AB represents the height of the moulding.

13. What is a Torus, and how traced?

It is a moulding similar to the bead, but thicker. It is

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