Page:EB1911 - Volume 17.djvu/375

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360
MAGNETISM, TERRESTRIAL
  


Table II.—Recent Values of the Magnetic Elements and their Rate of Secular Change.

Place. Geographical position. Absolute Values of Elements. Secular change (mean per annum).
Latitude. Longitude. Year. D. I. H. V. Interval
in years.
D. I. H. V.
    °  ′   °  ′     °  ′   °   ′         ′   ′    
 Pavlovsk 59 41N  30 29E  1906  1  4.2E 70 36.6N .16528 .46963 5 −4.5 +0.1 − 6 −14
 Sitka (Alaska) 57  3N 135 20W 1906 30  3.3E 74 41.7N .15502 .56646 4 −3.0 −1.6 +18 −38
 Ekatarinburg 56 49N  60 38E 1906 10 31.0E 70 49.5N .17664 .50796 5 −4.5 +1.7 −23 +18
 Rude Skov (Copenhagen)  55 51N  12 27E 1908 9 43.3W 68 45N  .17406 .44759          
 Stonyhurst 53 51N  2 28W 1909 17 28.6W 68 42.8N .17424 .44722 5 −5.9 −1.1 + 6 −25
 Hamburg 53 33N  9 59E 1903 11 10.2W 67 23.5N .18126 .43527          
 Wilhelmshaven 53 32N  8  9E 1909 11 46.8W   .18129   5 −5.2   − 7  
 Potsdam 52 23N  13  4E 1909 9 10.6W 66 20.0N .18834 .42971 5 −5.8 +0.1 − 9 −19
 Irkutsk 52 16N 104 16E 1905 1 58.1E 70 25.0N .20011 .56250 5 +0.6 +2.0 −24 +39
 de Bilt 52  5N  5 11E 1907 13 19.0W 66 49.9N .18559 .43368 5 −4.7 −0.6 + 2 −16
 Valencia 51 56N  10 15W 1909 20 50.3W 68 15.1N .17877 .44812 5 −5.0 −1.2 + 7 −25
 Kew 51 28N  0 19W 1909 16 10.8W 66 59.7N .18506 .43588 5 −5.4 −1.1 + 2 −35
 Greenwich 51 28N  0  0 1909 15 47.6W 66 53.9N .18526 .43432 5 −5.5 −0.7 + 1 −20
 Uccle 50 48N  4 21E 1908 13 36.7W 66  1.6N .19061 .42867 4 −5.3 −0.8 − 3 −35
 Falmouth 50  9N  5  5W 1909 17 48.4W 66 30.6N .18802 .43266 5 −4.7 −1.4 + 9 −30
 Prague 50  5N  14 25E 1908 8 20.9W       5 −6.5      
 Cracow 50  4N  19 58E 1909 5 35.1W 64 18N      3 −7.3      
 St Helier 49 12N  2 5W 1907 16 27.4W 65 34.5N     5 −5.3 −1.2    
 Val Joyeux 48 49N  2 1E 1909 14 32.9W 64 43.9N .19727 .41792 5 −5.4 −1.7 + 1 −51
 Vienna 48 15N  16 21E 1898 8 24.1W                
 Munich 48  9N  11 37E 1906 9 59.5W 63 10.0N .20657 .40835 5 −4.8 −1.3 + 4 −31
 O’Gyalla 47 53N  18 12E 1909 6 43.9W   .21094   5 −5.0   −10  
 Odessa 46 26N  30 46E 1899 4 36.7W 62 18.2N .21869 .41660          
 Pola 44 52N  15 51E 1908 8 43.2W 60  6.8N .22207 .38640 5 −5.5 −0.6 − 4 −23
 Agincourt (Toronto) 43 47N  79 16W 1906 5 45.3W 74 35.6N .16397 .59502 4 +3.4 +0.9 −23 −24
 Nice 43 43N  7 16E 1899 12  4.0W 60 11.7N .22390 .39087          
 Toulouse 43 37N  1 28E 1905 13 56.3W 60 49.1N .22025 .39439 5 −4.5 −1.5 + 2 − 2
 Perpignan 42 42N  2 53E 1907 13 4.4W       7 −4.7      
 Tiflis 41 43N  44 48E 1905 2 41.6E 56 2.8N .25451 .37799 7 −5.2 +1.7 −26 + 2
 Capo di Monte 40 52N  14 15E 1906 8 40.3W 56 13.5N     5 −5.1 −1.5    
 Madrid 40 25N  3 40W 1901 15 35.6W                
 Coimbra 40 12N  8 25W 1908 16 46.2W 58 57.3N .22946 .38120 5 −4.6 −2.9 +17 −45
 Baldwin (Kansas) 38 47N 95 10W 1906 8 30.1E 68 45.1N .21807 .56081 4 −1.7 +1.8 −36 − 8
 Cheltenham(Maryland) 38 44N 76 50W 1906 5 22.0W 70 27.3N .20035 .56436 4 +3.8 +1.2 −38 −45
 Lisbon 38 43N  9  9W 1900 17 18.0W 57 54.8N .23516 .37484          
 Athens 37 58N  21 23E 1908 4 52.9W 52 11.7N .26197 .33613 5 −5.5      
 San Fernando 36 28N  6 12W 1908 15 25.6W 54 48.4N .24829 .35206 5 −4.6 −2.8 +26 −24
 Tokyo 35 41N 139 45E 1901 4 36.1W 49  0.0N .29954 .34459          
 Zi-ka-wei 31 12N 121 26E 1906 2 32.0W 45 35.3N .33040 .33726 5 +1.5 −1.3 +30 + 6
 Dehra Dun 30 19N  78  3E 1907 2 38.3E 43 36.1N .33324 .31736 4 +0.8 +5.5 −26 +77
 Helwan 29 52N  31 21E 1909 2 49.2W 40 40.4N .30031 .25804 5 −5.7 +1.2 − 6 +13
 Havana 23  8N  82 25W 1905 2 25.0E 52 57.4N .30531 .40452          
 Barrackpore 22 46N  88 22E 1907 1  9.9E 30 30.2N .37288 .21967 3 +4.2 +3.4 +21 +62
 Hong-Kong 22 18N 114 10E 1908 0  3.9E 31  2.5N .37047 .22292 5 +1.9 −1.8 +43 − 1
 Honolulu 21 19N 158  4W 1906 9 21.7E 40  1.8N .29220 .24545 4 −0.9 −3.2 −19 −62
 Kolaba 18 54N  72 49E 1905 0 14.0E 21 58.5N .37382 .15084 5 +2.1 +7.2 −11 +86
 Alibagh 18 39N  72 52E 1909 1  0.3E 23 29.0N .36845 .16008 3 +1.7 +6.8 −10 +82
 Vieques (Porto Rico) 18  9N  65 26W 1906 1 33.2W 49 47.7N .28927 .34224 2 +7.2 +6.8 −49 +66
 Manila 14 35N 120 59E 1904 0 51.4E 16  0.2N .38215 .10960 5 +0.1 −3.9 +47 −34
 Kodaikanal 10 14N  77 28E 1907 0 40.7W 3 27.2N .37431 .02259 4 +4.3 +5.5 +16 +61
 Batavia  6 11S 106 49E 1906 0 54.1E 30 48.5S .36708 .21889 4 +2.1 −7.7 − 2 +110
 Dar es Salaam  6 49S  39 18E 1903 7 35.2W                
 Mauritius 20  6S  57 33E 1908 9 14.3W 53 44.9S .23415 .31932 5 −0.3 +2.9 −53 −131
 Rio de Janeiro 22 55S  43 11W 1906 8 55.5W 13 57.1S .24772 .06164 5 +9.1 −6.8 −42 +44
 Santiago (Chile) 33 27S 70 42W 1906 14 18.7E 30 11.8S     3 +6.1 +9.9    
 Melbourne 37 50S 144 58E 1901 8 26.7E 67 25.0S .23305 .56024          
 Christchurch, N.Z. 43 32S 172 37E 1903 16 18.4E 67 42.3S .22657 .55259          


Table III.—Declination at London.

Date. Declination. Date. Declination. Date. Declination.
  °   ′    °   ′    °   ′ 
 1580  11   15E  1773  21   9W  1860   21   38.9W
1622  6    0  1787 23   19 1865 20   58.7
1634  4    6  1795 23   57 1870 20   18.3
1657  0    0  1802 24    6 1875 19   35.6
1665  1   22W 1805 24    8 1880 18   52.1
1672  2   30  1817 24   36 1885 18   19.2
1692  6    0  1818 24   38 1890 17   50.6
1723 14   17  1819 24   36 1895 17   16.8
1748 17   40  1820 24   34 1900 16   52.7
        1905 16   32.9

§ 12. Table VII. gives particulars of the secular change of horizontal force and northerly inclination at London. Prior to the middle of the 19th century information as to the value of H is of uncertain value. The earlier inclination data[1] are due to Norman, Gilbert, Bond, Graham, Heberden and Gilpin. The data from 1857 onwards, both for H and I, refer to Kew. “London” is rather a vague term, but the differences between the values of H and I at Kew and Greenwich—in the extreme west and east—are almost nil. For some time after its discovery by Robert Norman inclination at London increased. The earlier observations are not sufficient to admit of the date of the maximum inclination or its absolute value being determined with precision. Probably the date was near 1723. This view is supported by the fact that at Paris the inclination fell from 72° 15′ in 1754 to 71° 48′ in 1780. The


  1. (1) p. 166.