MAGNETIC SURVEY OF GREAT BRITAIN. 



151 



2. Mr. Lloyd's observations were made with two cylinders, 

 L (a) and L {b), vibrated in Hansteen's apparatus. The 

 agreement of their times of vibration in Dublin, in April and 

 May 1836, is an evidence that their magnetic state I'emained 

 unaltered in the interval. The values of the intensity at 

 Shrewsbury and Holyhead are deduced, in relation to the Lon- 

 don unity, by means of the force in Dublin ; which, in a sub- 

 sequent part of this Report, will be shown to be 1'0195. The 

 coefficient in the formula of reduction to a mean temperature, 

 is -00025 for both cylinders. (5th Report, B. A., pp. 119 and 

 120.) 



3. Major Sabine's observations were made with Mr. Lloyd's 

 cylinders L (a) and L (b), and with a pair, in all respects simi- 

 lar, designated as L (3) and L (4). The results are comprised 

 in the two following Tables, LII. and LIII. Table LII. con- 

 tains observations made to determine the value of the intensity 

 at Tortington, in Sussex ; and Table LIII. the values at six other 

 stations in Great Britain : in Table LIII. the value of the force 

 in Dubhn =1'0195, has supplied the means of checking the 

 magnetism of the cylioders. 



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