on the Distribution of the Magnetic Intensity. 5 



STED, in the year 1823. But at the time I was making my ex- 

 periments, I considered them objectionable, from the great quan- 

 tities of iron in the vicinity, used as pipes for the conveyance of 

 water, railing, &c. I mentioned this to Captain HALL and Pro- 

 fessor WALLACE, who were present at the experiments, and af- 

 terwards to Mr ADIE, who kindly requested me to make my ex- 

 periments in his field at Canaan Cottage, where such objections 

 could not apply. I accordingly did so, in company with Profes- 

 sor WALLACE and Captain ROBERTSON, R. N., and found a dif- 

 ference of about 10 seconds in the time of the needle making 

 300 vibrations at the respective stations, which is nearly the 

 amount of the difference between Professor HANSTEEN'S lines 

 and mine. 



I should not omit to mention, that the needles have always 

 been kept separate, and in their respective cases, and that their 

 magnetism has not been disturbed since they came into my pos- 

 session. I am, Sir, your humble servant, 



JAMES DUNLOP. 



