Mr. R. Webster on the Variation eft he Magnetic Pole. 165 

 _ Further, as any other point G may be assumed, correspond- 

 ing pomts R I and H will be obtained : hence it follow that 

 a polygon of m sides may be inscribed in a circle so as to Imv^ 

 «^-3 or ;«-4 points of intersection in the sam .^ra Ut hne 

 accordmg as m is an even or odd number. "" ' 



th.n 1 \r^ ^^"^ ^°^"^' ^' ^ '^^^^l^^'^e '-^"^1 the line drawn 

 plough hem passes mto a tangent, corresponding points w 

 be found n. the pentagon: and when any other ^n\ AB d o 



drSSIh "^"'"^' ""'"■ P^"P""^^^-^ ^"^ «--• '" the qt! 



XXXVI. On the Causes of the Variation of the Magnetic 



Pole. By Mr. Richard Websteii. 



To the Editm-s of the Philosophical Magazine and Journal. 



QN the return of Captain Parry from exploring the North 



y wes passao^, ,„ which he succeeded as ftu- asS llde^ ees 



uLn "^^'"'^'^ ^"^"^^ "^-^^^ the following n,X, 



=t-a^i:ih;=rl^^^^^^ 



Cornhill. t n ^ 



1 am yours, &c. Rd. Webster. 



cui„,- fi,,.,,;:, „\i„z ,, 77,', "T '='"■"' f i" -•"■.>■ i'-"i- 



wuvs llio ir,»».f f ■ ' '" '''='"<''■ 'Iq'osts bcinirul- 



ciL vl r /e Sir;" '","■'■■ '"^ '.""'-^ '" ""if-nn-suc. 



own 



