^ 



Observations of Absolute Horizontal Intensity, 1847. 



351 



Gott. 

 Mean 

 Time. 



Deflecting Bar. 



Distance 



N. 

 Pole. 



Tem- 

 pera- 

 ture. 



Unifilar. 



Circle 

 Reading. 



Scale 

 Reading. 



Sc. Div. 



Declino- 

 meter. 



Unifilar 



Circle Reading 



Reduced. 



Deflection. 



BiFILAR. 



Reading 



Cor- 

 rected. 



Sc. Div. 



Ther- 

 mome- 

 ter. 



Log. 

 i r^ sin. 



:i 46 



2 56 



3 3.3 

 3 6 

 3 37 

 3 2 



26 

 13 



3 23 

 3 16 

 3 55 



0-85-^ 



M0{ 



l-55<^ 



E 



W- 



W- 



W 



E 



56-6 



W 



53-2 



E 



56-3 



W 



53-4 



E 



55-8 



W 



54-1 



E 



55-9 



W 



53-8 



E 



55-3 



W 



54-6 



E 



550 



W 



54-6 



t awa; 



Y- 







September 13— 



260 30 



42 



56-41 



8-00 



213 17 



5 



44-27 



12-17 



260 30 



42 



45-12 



8-57 



213 17 



5 



40-65 



10-75 



247 46 



18 



44-55 



8-85 



226 11 



32 



46-52 



11-07 



247 46 



18 



40-37 



8-55 



226 11 



32 



45-37 



11-05 



240 46 



30 



45-85 



9-92 



233 6 



43 



45-96 



10-55 



240 46 



30 



44-76 



9-87 



233 6 



43 



45-67 



10-62 



236 56 



7 



44-74 



715 



14, 1847. 



260 



48 20 ] 



213 



7 25 



260 



25 10 



213 



1 5 



247 



39 27 ) 



226 



7 9 



247 



31 13 



226 



4 51 



240 



41 32 ] 



233 



1 34 



240 



39 23 



233 



55 



236 



50 47 



23 46 15 



10 44 40 



3 49 36 



536-5 



50-2 



'^ 



535-4 



50-2 





535-1 



50-2 





536-4 



50-2 





535-6 



50-2 





534-0 



50-2 





534-5 



50-2 





533-6 



50-2 





534-1 



50-2 





534-1 



50-2 





534-4 



50-2 





533-9 



50-2 



-' 



9-0941498 



90945213 



9-0948615 



The observations, June 23, 1846 and Jan. 2, 1847, were made with a unifilar magnetometer, by Mr Jones of London, belonging to 

 Professor Forbes. The observations, May 31, June 15, Sept. H, and Sept. 14, 1847, were made with a theodolite magnetometer, by 

 \Ir Jones, belonging to Sir Thomas Brisbane. 



The following magnets were used in these observations : — 



June 23, 1846. Suspended. Solid, 2-5 inch. Deflector. 



Jan. 2,1847 30 inch. 



May 31, 1847 Hollow (with mirror), 3-0 inch B. 6. 



June 15, 1847 Idem. 



Sept. 1 1, 1847 Collimator, 3-0 inch. 



Sept. 14, 1847 Idem. 



Solid, 3'65 inch. P. 

 Idem. F. 



Collimator, 3-65 inch. M. 



Idem. M. 



Idem. M. 



Collimator marked 4. B. 



The magnets used on the first two days belong to Professor Forbes' instrument ; those used afterwards belong to Sir Thomas Bris- 

 bane's instrument, with the exception of the collimator deflector marked 4, used Sept. 14, 1847, which belongs to an instrument made 

 )y Mr Jones for Professor Bache of New York. 



An abstract of the observations for the times of vibrations of the different deflectors is given on the following page, and the final 

 ■esults will be found in the Addendum to the Introduction. 



