Aquaculture Engineering

Experiment No 1 - Plotting of the position of objects by radiation and intersection method

Practical - 7
Experiment No 1 - Plotting of the position of objects by radiation method

Aim:
To plot the position of given ground points by radiation method.

Apparatus:
Plane table with accessories, Ranging rods, Tape, Arrows, etc.

In this method a ray is drawn from the instrument station towards the point, the distance is measured between the instrument station and the point, and the point is located by plotting to suitable scale the distance so measured. This method is more suitable when the distances are small and single instrument can control the points to be detailed.

Procedure:

• Set the table at ‘T’, level it and transfer this point on to the sheet by means of plumbing fork, thus getting‘t’ representing ‘T’. Clamp the table.
• Keep the alidade touching‘t’ and sight to ‘A’. Draw the ray along the fiducial edge of the alidade. Similarly sight different points B, C, D and E etc and draw the corresponding rays (A pin may be inserted at ‘t’ and the alidade may be kept touching the pin while sighting the points).
• Measure TA, TB, TC, TD and TE etc in the filed and plot their distances to suitable scale along the corresponding rays thus getting a, b, c, d etc. Join these if needed.