RESULTS OF SPIRIT LEVELING IN THE STATE OF NEW YORK 
FOR THE YEARS 1896 TO 1905, INCLUSIVE. 
By S. S. Gannett and D. H. Baldw 
INTRODUCTION. 
The readjustment in 1903 of the precise-level net in the eastern portion of the United 
States by the United States Coast and Geodetic Survey necessitated a corresponding 
readjustment of all spirit-level heights of the United States Geological Survey dependent 
thereon. These results will be summarized by States or groups of States and published 
from time to time in bulletin form. 
All results of leveling in New York State previously published in appendices to reports 
of the Director of the United States Geolgoical Survey and in Bulletin No. 185, as well as 
levels not previously published, have therefore been readjusted, rearranged by quadran- 
gles, and collected herewith in one publication. Descriptions and elevations of bench 
marks are given in nearly every county, furnishing vertical control for fully eight-tenths 
of the total area of the State. 
The field work was done in cooperation with the State of New York, under the direction 
of Mr. H. M. Wilson, geographer, United States Geological Survey, by various topogra- 
phers and levelmen of the United States Geological Survey, to whom due credit is given 
under the different headings listed in the following pages. 
The office work of adjustment was principally done by Mr. D. H. Baldwin, topographer, 
assisted by C. B. Kendall, field assistant, under the supervision of Mr. S. S. Gannett, 
geographer in charge of the triangulation and computing section. 
The elevations are arranged according to the degree of accuracy of their determination, 
precise and primary, the former being determined by lines of levels run either in both the 
forward and backward directions or by simultaneous double-rodded lines, using a high- 
grade instrument and taking special precautions in observations and reductions to correct 
errors and make the line continuously good throughout; and the latter or primary levels 
being determined with the Y level with precautions taken against the principal errors 
and run mostly in circuits of single lines. 
The allowable limit of error observed on the precise work already done by t he ( reological 
Survey in this State is represented in feet by 0.03 s/D, and that for the primary work by 
0.05 \/D, in which D is the length of circuit in miles. 
The bench marks described in the following lists are of three general forms. First, a 
circular bronze or aluminum tablet 3h inches in diameter and one-fourth inch thick, appro- 
priately lettered, having a 3-inch stem cemented into a drill hole, generally in the 
vertical walls of public buildings, bridge abutments, or other substantial masonry 
structures. The second form, employed where masonry or rock is not accessible, consists 
of a hollow wrought-iron post 4 feet in length and 3| inches in outer diameter, split al tin 
bottom and expanded to 12 inches, so as to prevent both the easy subsidence of the post 
and its being maliciously pulled out of the ground. The iron is heavily coated with asphalt, 
and over the top of the post is riveted a bronze tablet similar to that described above. 
7 
