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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).
Place.	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.

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[f14-1] (1) p. 166.

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