of the Magnetic Poles of the Earth. 121 
Tobolsk the eastern declination increased; and again decreased 
towards Irkutsk, where it was only = 3°. Further east it 
must vanish entirely; for in Jakutskoi, Billings found in 1788, 
a westerly declination of 2°. Further east from Jakutskoi 
this western declination disappears again, and becomes in 
Kamtschatka, and the whole ‘of north-western America, again 
easterly. Thus we see that there are round the north pole 
four places where no declination is found: viz. 1st, on the 
west coast of Hudson’s Bay; 2dly, in the line between the 
White Sea and Casan; $rdly, alittle eastward of Irkutsk; and 
4thly, a little eastward of Jakutsk. Between the first and se- 
cond distance, z.e. in north-eastern America, the Atlantic 
Ocean, and all Europe, the declination is westerly; between the 
2d and 3rd, i. e. in the greater part of Siberia, it is easterly ; 
between the 3rd and 4th, 7. e. in eastern Siberia, it is westerly ; 
and between the 4th and Ist, z. ¢. in Kamtschatka, the northern 
part of the Pacific Ocean, and the north-west part of America, 
it is again easterly. 
If we continue the arrows which point out the direction of 
the magnetic needle in Siberia in the year 1805; for instance, 
in Tobolsk, Tara and Udinsk, we see them converge ‘in one 
point, situated about 5° from the pole, and between the meri- 
dians 110° and 120° E. of Greenwich. Ifwe combine the ob- 
servations, by pairs, and thereby calculate the position of the 
_ Magnetic point of convergence, we have the following results : 
Distance from | Longit. from 
From Nos. 
the Pole. Ferro. 
° ° i 
13 and 15 4 Q7 134 7 
6 — 15 4 50 133 31 
6 — 14 $ “51 155 54 
6 — 16 5 16 124 58 
Mean .. 4°36") 137 7% 
Thus the mean of all gives the distance from the pole at 
4° 36', and the longitude from Ferro =137° 7'3: but a mean 
of the two first which agree best, gives the distance from the 
pole at = 4° 38! 30", and the longitude from Ferro = 133° 49’, 
or 116° 9! from Greenwich. 
From the above observations it appears that the declination 
in Siberia has changed every where from 1761 to1805. Thus 
at Casan, it was in the year 1761 = 2° 25' W., in the year 
1805 = 2° 2' 30" E., or in forty-four years it had a change of 
= 4° 27’ 30", or 61 per annum. The change in Catha- 
Vol. 67. No. 334. Feb. 1826. Q rinenburg 
