After reading this article you will learn about: 1. Meaning of Plane Table Surveying 2. Advantages of Plane Table Surveying 3. Disadvantages 4. Equipment Needed 5. General Instructions 6. Errors 7. Testing and Adjusting. Contents: Meaning of Plane Table Surveying Advantages of Plane Table Surveying Disadvantages of Plane Table Surveying Equipment Needed in Plane Table Surveying General Instructions while Plane [...]
There are two main types of the field-book: 1. Single Line Field-Book 2. Double line Field-Book. The field measurements, sketches and relevant notes are recorded for future reference in a note book, known as field-book. The field-book in general use is about 20cm * 12cm and opens length wise. Type # 1. Single Line Field-Book (Fig. 3.18, b): Every page [...]
Plotting means to represent on paper, to a suitable scale, the previously surveyed objects in accordance with their shape and size. Plotting is commenced after the field-work is over. The plotting of a chain survey is done in the following steps: (i) A suitable scale is chosen before starting the plotting work. The scale depends upon the importance of the [...]
This article throws light upon the top five instruments that are used for setting out right angles and finding the foot of perpendicular from the object on the lines. The instruments are: 1. Cross Staff 2. Optical Square 3. Prism Square 4. Offset Rod 5. Measuring Tape. Instrument # 1. Cross-Staff: It is generally found in two patterns: (i) Open [...]
The following are the points of differences between prismatic and surveyor’s types of compasses. Difference # Prismatic Compass: 1. The graduated ring being attached to the magnetic needle remains stationary when the compass-box and the sight vane is rotated. 2. The graduations are marked on the ring in a clock-wise direction with 0° or 360" at South end of the [...]
There are two forms of the compass in common use: 1. The Prismatic Compass 2. The Surveyor's Compass. A compass is a small instrument which consists essentially of a magnetic needle, a graduated circle and a line of sight. When the line of sight is directed towards a line, the magnetic needle points towards magnetic meridian and the angle which [...]
The following two methods are generally adopted to find the areas from the previously plotted plans. The methods are: 1. Graphical Method. 2. Instrumental Method. 1. Graphical Method: In this method, the required data is obtained from measurements of the plan. The area may be found: (i) By the help of some geometrical figures or (ii) By the application of [...]
After reading this article you will learn about eight main precautions that should be taken while using a compass. Also learn about the sources of error in compass work. 1. The glass cover of the compass box gets charged with electricity when dusted off with a handkerchief or by the influence of electric charge in the atmosphere. Consequently, the needle [...]
The compass ring is graduated to half a degree but the readings can be well estimated to 15 minutes, which means that the error of reading should not exceed 7½ minutes. But due to magnetic changes and variation of declination etc., the readings can seldom be relied upon to less than 10 minutes, therefore, the permissible error per bearing should [...]
After reading this article you will learn about the meaning of bearing of a line and its designation with examples. Bearing of a line is the horizontal angle which a line makes with some reference direction also known as meridian. The reference direction may be any of the following: 1. A true meridian 2. A magnetic meridian 3. An assumed [...]