illustrations.
 

1     The Coast and Geodetic Survey precise level of 1900, right side view..........       12

2     The Coast and Geodetic Survey precise level of 1900, left side view...........       13

3     The Coast and Geodetic Survey precise level of 1900, longitudinal section......       15

4     Prisms of level reading device; vertical section..............................       20

5     Prisms of level reading device; horizontal section............................       ao

6     Precise leveling rod, lower portion, with foot plate and foot pin...............       22

7     Foot plate and foot pin..................................................       26

8     Method of testing precise level; first position...............................       29

9     Method of testing precise level; second position.............................       29

10     Rod corrections........................................................       33

11     Method of reciprocal leveling for river crossings............................       43

12     Types of targets used in reciprocal leveling..................................       48

13     Board of Estimate and Apportionment precise level net......................       49

14     The new datum plane chart..............................................       55

15     Standard bench marks, set-bolt types.....................................       56

16     Standard bench marks, ground monument types............................       57

17     Standard bench mark types .............................................       58

18     Method used for taking rod readings on bolts set horizontally into masonry. ...       59

19     Precise level lines in New Jersey, which were re-run in igil..................       79

20     Submerged stumps resulting from normal retrogression of the shore line.......       84

21     Submerged peat and stumps produced by an invasion of peat bogs by the sea. .       84

22     Submerged peat........................................................       85

23     Soil shrinkage due to draining of peaty soil.................................       85

24     Bay separated from the open ocean by a barrier beach......................       86

25     Diagram showing fictitious subsidence of the coast..........................       87

26     Diagram showing fictitious elevation of the coast...........................       87