OBSTACLES IN ANGULAR SURVEYING. CHAPTER I. Perpendiculars and Parallels. 279 280. (402) To erect a perpendicular to a line at a given point.... (403) To erect a perpendicular to an inaccessible line, at a given point of it 280 (404) To let fall a perpendicular to a line, from a given point.... (405) To let fall a perpendicular to a line, from an inaccessible point...... 280 (406) To let fall a perpendicular to an inaccessible line from a given point.. 281 (407) To trace a line through a given point parallel to a given line... 281 (408) To trace a line through a given point parallel to an inaccessible line.. 281 ARTICLE CHAPTER II. Obstacles to Alinement. (409) General method A. To prolong a line .... PAGE 282 (411) By an equilateral triangle. 282 (414) To prolong a line with only (412) By triangulation..... 283 an angular instrument... 283 B. To interpolate points in a line ..... 284 284 | (418) By Latitudes and Depart- CHAPTER III. Obstacles to Measurement. 287 ... 287 A. When both ends of the line are accessible (421) Previous means (422) By triangulation B. When one end of the line is inaccessible (425) By perpendiculars.... (426) By equal angles. ........ ..... 288 288 (429) To find the distance from a given point to an inaccessible line... 288 289 (428) When one point cannot be 289 seen from the other C. When both ends of the line are inaccessible.......... 290 (430) General method....... seen 291 CHAPTER IV. To Supply Omissions. (439) General statement 297 (440) CASE 1. When the length and bearing of any one side are wanting.... 298 CASE 2. When the length of one side and the bearing of another are wanting When the deficient sides adjoin each other When the deficient sides are separated from each other. 299 299 ....... CASE 3. When the lengths of two sides are wanting.. 300 300 801 301 447) CASE 4. When the bearings of two sides are wanting.. 802 302 (448) When the deficient sides are separated from each other. 802 CHAPTER I. Copying Plats. 316 | (474) Reducing by squares...... 819 (481) Signs for natural surface... 824 (485) Signs for detached objects. 327 PART XI. LAYING OUT, PARTING OFF, AND DIVIDING UP LAND. E. By a line passing through a given point within the field. (528) By lines perpendicular to a side 347 347 348 (540) Do. (541) (529) By lines running in any given direction (530) By lines starting from an angle (531) By lines starting from a point in a side (535) By lines passing through a point within the triangle Do. (512) By the the point being to be found. (543) By lines parallel to a side.. 348 349 349 851 353 the point to be equidistant from the angles shortest possible line.... Division of Rectangles. 354 (550) By lines running in any given direction (551) By lines starting from an angle (552) By lines starting from points in a side... (554) By lines passing through a point within the figure Division of Polygons. (555) By lines running in any given direction.. (558) By lines passing through a point within the figure 356 358 358 358 358 359 360 360 361 361 361 |