Account of a Case of Hi/drophohia. 257. 



that it is perhaps more prudent to abstain from any prema- 

 ture opinion on phenomena the cause of" which is totally 

 unknown to us. 



To employ the other observations of M. Humboldt in re- 

 gard to the inclination, I first reduced the terrestrial latitudes 

 and loaaitudcs reckoned from the magnetic equator. The 

 latter, being reckoned from the node of that equator in the 

 South Sea, I could first perceive bv these calculations that 

 the position of that plane determined by our preceding re- 

 searches was pretty exact; for some of the places, such as 

 Santa-Fe and Javi'la, where M. Humboldt observed incli- 

 nations almost equal, were found nearly on the magnetic 

 parallel, though distant from each other more than 6- 6666" 

 (6°) in longitude*. 



When these reductions were made, I endeavoured to re- 

 present the signs of the inclinations observed, and to leave as 

 little to chance as possible. I first tried a mathematical 

 hypothesis conformable enough to the idea which has hi- 

 therto been entertained in regard to terrestrial magnetism. 



I have supposed in the axis of the magnetic equator, and 

 at an equal distance from the centre of the earth, two cen- 

 tres of attractive forces, the one austral and the other boreal, 

 in such a manner as to represent the two opposite magnetic 

 poles of the earth : I then calculated the eft'ect which ought 

 to result from the action of these centres in any point of the 

 surface of the earth, making their attractive force recipro- 

 cally vary as the square of the distance ; and in this manner 

 I obtained the direction of the result of their forces, which 

 ouoht to be that also of the magnetic needle in that latitude. 



-- [To be continued.] 



XXXVII I. Account (f a Case of Hj/clrophohia siicccssfilhj 

 treated hj copious Bleeding and Mercury. In two Let" 

 ten from Dr. Kocekt Burtox, of Bent, in the State 

 of Virginia^ to Dr. Benjamin Rush, of Philadclphiaf. 



SIR, 



JjELiEViNG that you arc always disposed to encourage 

 any thing which may throw light upon the treatment of 

 diseases, I take the liberty of addressing to you the fpllow- 



• This confirms what we have already said, that the magnetic equator ii 

 sensibly a great circle of the earth. — Note of the Authori. 

 f From the Aiwricaii Medicnl Rcpusitory. 



Vol. 22. No. 87. Aumst 1805. R iog 



