LAND AND ENGINEERING SURVEYING.

CHAPTER I. Previous to commencing the various subjects of Land and Engineering Surveying, it will be necessary to give a clear view of Practical Geometry, which is especially requisite for those who are unacquainted with this branch, as well as those parts of the Mathematics which are equivalent to it.

DEFINITIONS. 1. A point has no dimensions, neither length, breadth, nor thickness.

А

2. A line has length only, as A.

3. A surface or plane has length and

B breadth, as B.

4. A right or straight line lies wholly in the same direction, 5. Parallel lines are always at the same

B distance from each other, and never meet

D when prolonged, as A B and C D.

6. An angle is formed by the meeting of two lines, as A C, C B. It is called the angle ACB, the letter at the angular point C C being read in the middle. 7. A right angle is formed by one right

A line standing erect or perpendicular to an

D other; thus, ABC is a right angle, as is also A BE.

8. An acute angle is less than a right angle, as D BC. 9. An obtuse angle is greater than a right angle, as D'BE.