ANS:C - level

1. Magnetic Compass:
   • A magnetic compass is a basic navigation tool that uses the Earth's magnetic field to determine direction. In the context of sewer laying, a magnetic compass might be used for initial orientation and alignment. Engineers may use it to establish a general direction for laying out the sewer lines before more precise measurements are taken.
2. Theodolite:
   • A theodolite is a precision instrument used for measuring angles in the horizontal and vertical planes. It consists of a telescope mounted on a base that allows for rotation in both horizontal and vertical axes. In sewer laying, theodolites are commonly used to measure angles accurately, ensuring proper alignment and slope of the sewer pipes. Engineers can use theodolites to set gradients and ensure that the sewer lines are laid with the appropriate slope for effective drainage.
3. Level:
   • A level is a tool used to determine the horizontal plane or level surface. In sewer laying, engineers use levels to ensure that the sewer pipes are installed horizontally along their length. This is crucial for maintaining uniform flow and preventing the accumulation of debris or blockages within the sewer lines. Levels may also be used to check the elevation of manholes and other sewer components relative to each other.
4. Clinometer:
   • A clinometer is a device used to measure the angle of slope or inclination relative to the vertical or horizontal plane. In sewer laying, clinometers are employed to verify the slope of the terrain or the gradient of the sewer pipes. Engineers use clinometers to ensure that the sewer lines are laid with the correct slope to facilitate the flow of wastewater by gravity. This helps prevent stagnant water and ensures efficient drainage.
5. Plane Table:
   • A plane table is a surveying instrument used for mapping and plotting topographic features directly onto a flat surface. While not as commonly used in modern surveying practices, plane tables were historically utilized for sewer laying projects to create detailed maps of the terrain and plan the layout of sewer networks. Engineers would use the plane table to record the location of manholes, sewer lines, and other relevant features, aiding in the overall design and implementation of the sewer system.