156 



quantity which varies from about 5' of angle to about 10', the 

 greatest difference being in the warm months and the least in 

 the cold months. But on this subject, other methods of research 

 than mine have lately introduced greater exactness than I could 

 attain to. 



Inclination of the Needle. 



The needle being constructed to move freely in a vertical 

 plane, which includes the magnetic meridian, and perfectly 

 equipoised, is found in this region to incline downwards or dip 

 at the north end. The angle of this Inclination or dip, as 

 measured from the horizontal line in the plane of the meridian, 

 is at this time a little above 70°, and appears to be slowly but 

 unsteadily diminishing. 



My first observations on this subject have the date of 1833, and 

 were made with needles of my own construction. In 1837, I 

 obtained a beautiful instrument (the Dip Circle) from the late 

 Mr. Charles Robinson, of Devonshire Street, and it still remains 

 in my hands, a highly prized memorial of that skilful maker. 



"With this instrument I have surveyed the County, and deter- 

 mined the magnetic dip at more than forty stations by series 

 of observations. I will first collect the results obtained at 

 York. 



Needle 1. Needle 2. 



1837, June 3rd.— 2| p.m. ... 70°„ 47 '9 70%, 48 "7 



