p.3

[Left Page]
[grapg Milwaukee City zero of grades 5 ft below Lake Survey zero]

[Right Page]
Table showing the Mean of Lake Michigan
monthly level of the Milwaukee River & Lake Michigan above
the City Zero of Street grades, which is the
level of the river in March 1836 and
four feet below the high water of 1838, which
last was one foot below the
Zero of the Lake Survey
Prepared by I. A. Lapham

[Monthly Lake survey, 1859-1871]