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Technology

Lesson 14 'බිම් මැනුම' (Land Surveying) හි ප්‍රධාන මාතෘකා:

• 📏 Surveying Principles — objectives, classification, scales, plans vs maps
• ⛓️ Chain Surveying — chains, tapes, ranging rods, offsets, field book
• 🧭 Compass Surveying — Prismatic compass, Whole Circle Bearing (WCB), Quadrant bearing
• 🔭 Levelling — Dumpy level, staff readings, Height of Instrument (HI) method
• 📊 Reduced Level (RL) calculations — Rise & Fall method; arithmetic check
• 🎯 Theodolite Surveying — horizontal & vertical angles, traverse
• 📋 Plane Table Surveying — radiation, intersection, traversing
• 🗻 Contour Lines — characteristics, interpolation, contouring methods
• 📐 Area & Volume — Mid-ordinate, Simpson's rule; prismoidal formula

HI (Height of Instrument) Method:

HI = RL + BS  |  RL = HI − FS  |  Check: ΣBS − ΣFS = Last RL − First RL

Rise & Fall Method:

• Rise = Previous staff − Current staff (if +ve)
• Fall = Current staff − Previous staff (if +ve)
• RL = Previous RL + Rise (or − Fall)

Staff reading types: BS (Back Sight) = first reading at BM; IS (Intermediate Sight) = intermediate points; FS (Fore Sight) = last reading at change point.

AL Tech Hub (altechhub.lk) හි Lesson 14 Downloads කොටසෙන් නොමිලේ:

• 📄 Full Notes PDF — 7.0 MB, 94 pages
• 📄 Chain Surveying Guide — 2.4 MB, 24 pages
• 📄 Compass & Bearing Notes — 2.2 MB, 22 pages
• 📄 Levelling & RL Calculations — 2.8 MB, 28 pages
• 📄 Theodolite & Traverse Notes — 2.6 MB, 26 pages
• 📄 Contour Lines Guide — 2.0 MB, 20 pages
• 📊 Slide Deck (PPTX) — 9.5 MB, 60 slides
• 📝 Practice Q&A (DOCX), Past Papers, 🗜️ Complete Bundle (ZIP 31 MB)

Chain Surveying — Horizontal distances only:

• Chains + tapes; small areas, open ground, simple

Compass Surveying — Distances + Magnetic bearings:

• Prismatic compass; WCB (0°–360°); larger areas

Levelling — Vertical differences only:

• Dumpy level + staff; elevation/RL measurement

Theodolite Surveying — Horizontal & Vertical angles:

• Precise; traverse surveys; control points; large areas