196 



REPORT ON THE MAGNETIC ISOCLINAL AND ISODY- 

 NAMIC LINES IN THE BRITISH ISLANDS. 



TABLE OF CONTENTS. 



Introduction page 49 



Division I. Dip. 



Errors of dipping needles, and recent improvements 51 



Annual alteration of the Dip 62 



Dip in London, May 1S3S 64 



Sect. L Observations in England 67 



Sect. 2. Observations in Scotland 86 



Sect. 3. Observations in Ireland. (This section is by Mr. Lloyd.) 91 



Summary, and deduction of the Isoclinal lines 120 



General table of the Dip observations 125 



Division II. Intensity, 



Sect. 1. Observations in f § 1. Statical method 138 



{ 



England. ... 1§ 2. Method of horizontal vibrations . . 148 



Sect. 2. Observations in f § 1. Statical method 155 



Scotland . . \§ 2. Method of horizontal vibrations . . 161 



Sect. 3. Observations in f § 1. Method of horizontal vibrations . . 165 



Ireland .... \ § 2. Statical method , 176 



(Section 3 is by Mr. Lloyd.) 



Summary, and deduction of the Isodynamic lines 186 



General table of the Intensity observations, by the statical method 190 



Conclusion. 

 Extension of the Isoclinal and Isodynamic lines into meridians east 



and west of the British Islands 193 



