Add notes on Fundamentals of Surveying (Part 2)

Added detailed notes on the fundamentals of surveying, including classifications, principles, measurements, and important units.

Author: developeranaz

study/notes/bmc/d44_e3.md

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+# Topic: Fundamentals of Surveying (Part 2)
+
+## 1. Recap of Part 1 🌍
+* **Primary Divisions:** Surveying is primarily divided into Plane Surveying and Geodetic Surveying.
+    * **Plane Surveying:** Earth's curvature is ignored (plumb lines are parallel). Used for smaller areas.
+    * **Geodetic Surveying:** Earth's curvature is taken into account (plumb lines converge at the earth's center). Used for areas greater than 250 km².
+
+## 2. Classification of Surveys 📋
+Surveying can be classified in three main ways:
+
+### A. Based on the Nature of the Field
+* **Land Survey:** Surveying done on land.
+* **Marine / Hydrographic Survey:** Surveying done on water bodies.
+* **Astronomical Survey:** Observations related to heavenly bodies.
+
+**Sub-classification of Land Surveys:**
+* **Topographical Survey:** Used to determine the natural features of a country such as rivers, streams, and hills, as well as artificial features.
+* **Cadastral Survey (Revenue Survey):** Used to fix the boundaries of municipalities, states, or properties. This is often called "Revenue Survey".
+* **City Survey:** Related to construction work within a city, such as streets, water supply systems, and sewers.
+
+### B. Based on the Object of Survey
+* **Engineering Survey:** To collect data for engineering works like dams or roads.
+* **Military Survey:** To determine points of strategic importance.
+* **Mine Survey:** To explore mineral wealth.
+* **Geological Survey:** To study the different strata of the earth's crust.
+* **Archaeological Survey:** To unearth relics of antiquity.
+
+### C. Based on Instruments Used 🔭
+* Chain Survey
+* Compass Survey
+* Leveling
+* Plane Table Survey
+* Theodolite Survey
+* Tacheometric Survey
+* Photogrammetric Survey
+* EDM (Electronic Distance Measurement)
+
+## 3. Basic Measurements 📏
+Surveying involves determining relative positions using a combination of:
+* Horizontal distances
+* Vertical distances
+* Horizontal angles
+* Vertical angles
+
+## 4. Principles of Surveying ⚖️
+There are two fundamental principles that are critical for exams.
+
+### Principle 1: Location of a point by measurement from two points of reference
+* To locate a new point (C), you need at least two known reference points (A and B), which form a base line.
+* Point C can be located using:
+    * Two distances (AC and BC).
+    * Two angles (Angle BAC and Angle ABC).
+    * One distance and one angle.
+
+### Principle 2: Working from Whole to Part
+* **Definition:** You establish a system of control points with high precision for the entire area first (the "Whole"), and then fill in the details (the "Part").
+* **Purpose:**
+    * To prevent the accumulation of errors.
+    * To localize minor errors (confining an error to a small area rather than letting it affect the whole survey).
+* **Contrast:** Working from "Part to Whole" is incorrect because errors will accumulate and expand as you proceed.
+
+## 5. Important Units and Conversions 🔄
+The lecture emphasizes knowing both British and Metric units, as they are common in fieldwork and exams.
+
+**Length:**
+* 1 Nautical Mile ≈ 1.852 km.
+* 1 Mile ≈ 1.609 km.
+* 100 Links = 1 Chain.
+* **Metric Conversions:**
+    * 10 mm = 1 cm
+    * 100 cm = 1 m
+    * 1000 m = 1 km
+
+**Area:**
+* 1 Acre = 10 Square Chains. (Important previous question).
+* 1 Are = 100 m².
+* 1 Hectare = 100 Ares = 10,000 m² (10^4 m²).
+
+## Practice Questions Discussed ❓
+* **Question:** Which survey determines natural features like mountains, rivers, and water bodies?
+    * **Answer:** Topographical Survey.
+* **Question:** Which survey is used to determine additional details such as boundaries of fields?
+    * **Answer:** Cadastral Survey.
+* **Question:** What is the fundamental principle of surveying?
+    * **Answer:** Working from Whole to Part.