(J Mr, Boner OH the [^.Vt^X, 



free from local attraction, or in other respects unfit for the 

 purpose. 



At London, in 1812, the variation was 

 24° 16' W. and the dip 70° 32'. To find the w 

 place of the niaonetic pole from these data. 



P, the pole of the earth. 



M, magnetic pole. 



L, London, latitude 51° 3 1' N. 



P L, complement of latitude 38° 29'. 



M L, complement of dip multiplied by 2 = 38* 66' z L = 

 24° 16'. 



1. Cosine ^^ > g ^^^ = 38° 42^ 9-892284 



2. Cosine 5LLz.Lil = o 13i- 9-999997 



' ' »:» €6te*^-^ =12 8 10-667500 



"^"^'"^^'^' " ^ » 20-667497 



^ 4. Tang4v.4^^|^:^.^iJ80^28;,g^^ 



. . ,A^ine, No,. ]i,,f>...a>>a*io«ij ^9*796127 ii£iaiflOYCl .. 

 ' '6. Sine, No. 2 7-58876d ; ,^ 



7. Cot. No.a^,,.^..^.^..«^a0-667500""'' ' 



^:^^J.,y^ '^h8-256260 



8. T.^^^^—^^hS^.^i... 8-460133 = 1° 39' 8'^ 



Hence ^ P =3=^82° 7' 36" 

 mti^ ^iM ^^S^ 49 20 o 



Sme,No.8.^^.^..^..^^^8-459^^^ - 

 Sme,No.4.^.^.^^^,..^^^..^,9-99^^^^ 

 Tang. 2 . . . .^^f,^^ . 4^j . ^^ 7-593764 



^ PM 00-8^ 88 ^r^7f7734 



Tang. ^ . M8^^ • -W- • • 9-127852 = 7° 38' 41^ 



.nL9iodcrr97ii/po?W ^ - C^^/r ^^.oihOo boi-ie^: -' 

 Thereforb the longitude of the magnetic polo in 1812 \Vas 

 82° 7' 36" west of London, and its latitude 74^^ 42' 37". In 

 1657 its longitude was 180; therefore in 155 years it has pro- 

 ceeded 97° 52' 24", or 37' 53"- 187 per annum. 



UR-^'Vi 'bo °08 ~ i -^ ^ .>i£ 



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