ARTICLE VI. 



On the Magnetic Dip at several places in the State of Ohio, and on the 

 relative Horizontal Magnetic Intensities of Cincinnati and London. 

 By John Locke, M. Z>., Professor of Chemistry and Fharm., Medical 

 College of Ohio. In a letter to John Vaiighan, Esq., Librarian of 

 the Jim. Philos. Soc. Head June 15, 1838. 



The extent of our continent and sea coast, the importance of our navi- 

 gation, and our proximity to the magnetic pole, all conspire to render ac- 

 curate magnetical observations highly interesting and useful. Yet, if we 

 except the labours of Professors Bache and Courtenay, very little has 

 been done by our countrymen, in this department of science. So far 

 as I know, nothing has yet been communicated from this side of the 

 Alleghanies. In my late journey abroad, it was no inconsiderable ob- 

 ject with me, to procure the instruments and the instructions neces- 

 sary for determining the elements of Dip, Declination, and Intensity, 

 especially in the western part of the United States. On arriving in 

 London, I was not a little gratified to find in the hands of one of our 

 own countrymen, Professor Bache, an apparatus invented by himself, 

 so perfectly adapted to the purpose of determining the Horizontal In- 

 tensity, by the vibration of the Hansteenian needles in a rarified me- 

 dium, that I at once ordered one to be made after the same model, by 

 the very skilful artisan Mr Robinson, of Devonshire street, London. 

 It has not disappointed my expectations. It is portable, easy of mani- 

 pulation, and gives results as consistent and satisfactory as the present 

 yi. — 3 R 



