Surveying and Levelling Instruments, Theoretically and Practically Described. For construction, qualities, selection, preservation, adjustments, and uses; with other apparatus and appliances used by civil engineers and surveyors in the field.

CHAPTER IV.

Chapter 432 wordsPublic domain

LEVELS:--Methods of Ascertaining--Level Tubes--Manufacture-- Curvature--Sensitiveness--Testing--Reading--Circular Levels-- Surveyors' Levels--Y-Levels--Parallel Plates--Adjustments of Y-Levels--Suggested Improvements--Dumpy Levels--Tripod Stands-- Adjustment of Dumpy--Collimator--Improvements in Dumpy Levels-- Tribrach Head--Diaphragms--Cushing's Levels--Cooke's Levels--Cheap Forms of Level--Hand Levels--Reflecting Levels--Water Levels 85