TERRESTRIAL MAGNETIC INTENSITY. 



27 



the isoclinal lines wonld, even by this instrument, have been deternnned with 

 very considerable exactness. The following Table contains observations made 

 with only one needle (marked No. II.), the other (from havmg too thick an axis) 

 having been found to give much more anomalous results. 



Table X. 

 Obsei-vations of Magnetic Dip with a Three Inch Circle. 



1832. 

 April 23. 



April 23. 

 May 23. 

 May 28. 



July 11. 

 July 17. 



July 27. 



Aug. 



Aug. 

 Aug. 

 Aug. 



Aug. 18. 



Aug. 20. 



Marked End 



Edinburgh. Greenbill 



House, . 

 Edinburgh, .... 

 Edinburgh, .... 

 Edinburgh . . . ■ 



Brussels Observatory, 

 (same place as intensity) 

 Spa (s.ame place as in- 

 tensity, .... 

 Heidelberg, 

 a. On the bank of thel 

 Neckar, two raUes > 

 above the town, . J 

 h. Prof. Leonhard's \ 

 garden, ... J 

 c. Terrace of the Castle, 



Laach ; S.E. side of Lake, 



Andernach; foot of the\ 

 hill west of the town, J 



Cologny, near Geneva,) 

 Prof. Necker's garden, ) 



Geneva Observatory, . 



Mount Breven, summit, 

 Chamouni (same place \ 



as intensity), . . J 



Jardin • 



Aoste (same place as in-\ 



tensity, .... j 

 St Bernard, near the Lake, 



Martigny, 



Bex; in an orchard S.W.I 



of the town, ... J 



Interlaken; sideof the Aar, 



Hospital; St Gothatd \ 

 near the old castle, J 



St Gothard Hospice 



Locarno (Lago Magiore) l 

 below the convent, J 



Pfeffers; near the Bath-\ 

 house, .... J 



Paris Observatory; M. 

 Arago's cabinet, . 



71.0' 



71.20 

 71.31 

 71.29 



68.55 



68.20 



C6.23 



66.20 

 66.33 

 67.58 



67.33 

 64.45 



64.56 



64.38 

 64.45 

 64.45 

 64.36 

 64.43 



64.35 



64.47 



65.13 

 65.10 



65.22 



64.50 



64.48 



S. Pole. 



} 



64.55 



67.B 



71.46 



71.42 

 71.46 

 71.45 



69.1 



68.24 



66.45 



66.44 

 66.59 

 68.22 



67.45 

 65.10 



65.14 



65.11 

 65.16 

 65.7 

 64.58 



65.7 



64.43 



65.14 



65..30 

 65.39 



65.31 



65.30 



65.13 



65.23 

 67.26 



71.23 



71.34 

 71.38 

 71.37 



68.58 



68.22 



66.84 



66.32 

 66.46 

 68.10 



67.39 

 64.57 



65.5 



64.54 



65.0 



64.58 



64.47 



64.55 



64.39 



65.0 



65.22 

 65.25 



65.26 



65.10 



65.0 



66.9 



67.17 



SMean 71° 33'.2. But the two last 

 observations are the best. These ob- 

 servations are the only ones made in 

 a house. 



f 68° 49' according to M. Quetelet, 

 (May 1832. 



Mean 66° 37'.1. I tave changed 

 the leadings at the first station from 

 67° to 66°, considering the former as 

 an undoubted error. This is confirm- 

 ed by observations made at the same 

 three stations by Needle No. 1., which 

 gave 66° 48', 66° 18', 66° 57'— Mean 

 66° 41'. 



Good observation. 

 f Good. The difference between this 

 J and the last probably due to volcanic 

 (influence. 



r 65° 48.'6 in 1825 (Arago). The 

 \ dip diminished at Paris about 27' be- 

 ttween 1825 and 1832. 



{ 



Difficult observation , Local influ- 

 ence being suspected, the operation 

 was repeated at Bex. 

 Very good observation. 



Indifferent observation. 



67° 24' by M. Arago. July 1835. 



iJ».«...-The dip at Edinburgh is --^o— y^f -^^^^f fecTn.^^^^^^^^^ foTnd theTp^ byXlm": 

 -rintt bl ?1° '^T^^\Z^;im)::^^<^ ^^.a^a^^ .li.^.y)-^U.o.,. ... ^, has been 

 diminishing every year. 



