Tuttle — Changes in Elevation of Land and Sea. 335 



M. L. W. — at the Battery as used by the Department of Docks 

 and Ferries which is known as Battery datum, and is 2*186 

 feet below the datum plane of the Coast and Geodetic Survey 

 in their levelling operations in the vicinity of New York City.*. 



The elevation of B. M^ from the above Coast and Geodetic 

 Survey levels is 14*203 feet, and from ordinary levels run 

 directly from the Battery to Governor's Island the elevation 

 14*160 was obtained. We shall adopt the former value in the 

 succeeding work. 



The following is the record of the observations at Governor's 

 Island for each year. 



Half tide level 

 Year. above zero of staff. 



1846 8*32 ft. 



1847 10*31 



1848 13-12 



1849 12-92 



1850 14-16 



1851 12-20 



1852 10-51 



1853 5-30 



1854 5-07 



1855 5-32 



1856 7*507 



1857 7-640 



1858 7 591 



1859 7-616 



1860 7-575 



1861 6-580 



1862 6*494 



1863 6-498 



1864 6-570 



1865 6-476 



1866 6468 



1867 6-615 



1868 6*557 



1869 6-435 



1870 4620 



1871 4-472 



1872 4-468 



1873 4-516 



1874 4-358 



1875 4-40 



1876 4-46 



1877 4-56 



1878 4-68 



1879 4-64 



Half tide level 

 above Battery datum. 



920 ft. 



690 



940 



778 



911 



862 



887 



846 



921 



835 



839 



911 



817 



809 



956 



898 



776 



961 



813 



809 



857 



699 



741 



801 



901 



021 



981 



, Probable 

 ' elevations 



* See appendix 14, Report of Coast and Geodetic Survey, 1887. 



