M A G N E TIC S T R V K V <> K P K N N S V I, V AN] \ 



55 



Al New York, 

 x. 



1835.0 



i ; 19.5 

 L842.7 

 1855.6 



1835.0 

 L859.6 



1835.0 



1842.8 

 1844.5 

 1844.5 

 1855.6 

 1856.7 

 1858.4 



Ai Providence. 



Bache & Courtenay 

 Loomis . 

 Lefroy . 

 Schott . 



Al Springfield. 



Bache & Courtenay 



Schott . 



At Albany. 



Bache & Courtenay 



Lefroy . 



Locke 



Locke 



Schott . 



Friesach 



Dean 



Columbia College. 



ii 

 Lunatic Asylum. 



Columbia < 'allege. 

 Lunatic Asylum, 

 ( !olumbia College 

 Bloom. Asylum. 

 Mi. Prosp 

 Bedloe' I land 

 Governor's Island. 

 Receh ing Re ervoii 

 Mt. Prospecl 



x. 

 3.770 

 3.726 

 3.715 



3.7-21 

 3.691 



3.578 

 3.579 

 3.582 



;;.:>: i 



3.587 

 ;: 575 

 3.574 



Reduction of the relative T<>i<tl Intensity Observations by Lloyd's Needles. 



Let 8 — true dip, 



£ = dip by :i Lloyd needle when unloaded, 



e = correction to £, 

 then h = £ -f- e, e may be assumed as constant for each lour. 



For finding the value of s we have the following results:— 



r' 



