Figure 8-11.-Horizontal distances and elevations from stadia readings.For the horizontal distance and elevation of point 1,set a rod on the point, and train the lower stadia hair ofthe transit telescope on a whole-foot mark on the rod sothat the center hair is near the 4.8 graduation. (This is acommon practice in stadia work that makes reading thestadia interval easier.) Then read and record the stadiainterval (in this case 6.23 feet). Next, rotate the telescopeabout the horizontal axis until the center hair is on the4.8 rod graduation. Lock the vertical motion and readand record the vertical angle (-3026’). Be sure to recordeach vertical angle correctly as plus or minus. While youare reading and recording the vertical angle, the rodmancan be moving to the next point. This will help speed upthe survey.From the stadia interval and the vertical anglereading, the horizontal distance (entered in the fifthcolumn of fig. 8-10) and the difference in elevation (inthe sixth column) are determined from a stadia reductiontable. Figure 8-11 shows the page from a stadiareduction table that applies to the data for point 1 infigure 8-10. For this point, the vertical angle is –3026’,8-11
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business