Chap. 1. 



DESCPJPTIVE GEOGRAPHY. 



19 



AURORA BOREALIS. 



MAGNETIC VARIATION. 



to the red belt was a belt of white light, 

 and beyond this in that direction, the sky 

 was mucli darker than usual, but no clouds 

 were any wjiere to be seen Tlie red belt, 

 increasing in width and briglitness, ad- 

 vanced towards the south and was in t!ie 

 zenitii of Burlington about 7 o'clock. Tlie 

 light was then equal to tlie full moon, and 

 the snow and every other object from 

 which it was reflected, was deeply tinged 

 with a red or bloody hue. Between t!ie 

 red and white belts, were frequently ex- 

 hibited streams of beautiful yellow light, 

 and to the northward of the red light 

 were frequently seen delicate streams of 

 blue and white curiously alternating and 

 blending with each other. The most 

 prominent and remarkable belt was of a 

 blood-red color, and was continually va- 

 rying in width and intensity. At eight 

 o'clock, the meteor, though still brilliant, 

 had lost most of its unusual properties. 



This meteor, when very brilliant, is usually 

 regarded as an indication of an approach- 

 ing storm, but, like other signs, it often 

 fails. It is most common in the months 

 of March, September and October, but it 

 is not unusual in the other montlis. 



Ma<rnetic Variation. — Very few obser- 

 vations have hitlierto been made in Ver- 

 mont for the purpose of determining the 

 variation of the magnetic needle, and 

 these few have generally been made with 

 a common surveyor's compass, and, prob- 

 ably, in most cases, without a very cor- 

 rect determination of the true meridian; 

 and hence they cannot lay claim to very 

 minute accuracy. But since such obser- 

 vations may serve to present a general 

 view of the amount and change of varia- 

 tion, since the settlement of the state, we 

 have embodied those to whicli we have 

 had access, in the following table. 



Magnetic Variation in Vermont. 



From repeated observations and from | 

 a careful examination of the lines of the 

 original surveys, John Johnson, Esq. was 

 of the opinion that in 1785, the westerly 

 variation at Burlington was about 7" 

 12' and that it diminished till the year 

 1805 when it was about 6^ 12". From 

 1805 the variation has been increasing 

 up to the present time, 1842; and is now 

 9° 54. This would give a mean annual 

 change of variation of 6' since 1805, and 

 of 3' previous to that time. And al- 

 though he thought the change of varia- 

 tion may not have been perfectly uiii- 

 form, yet he was of opinion that a table 

 constructed with the above variation 

 would not differ materially from the 

 truth. The following is such a table. 



Mag-nctic Variation at Burlington. 



Year Var.wiYear. Var.w Year.iVar.w Year. Var. 



6 24 

 6 21 



6 18 

 6 15 

 6 12 

 6 18 

 6 24 

 6 30 



1815 



1816 

 1817 



1818 

 1819 

 1820 

 1821 

 1822 

 1823 

 6 3611824 

 6 42' 1825 

 6 481 1 826 



6 54|l827 



7 1828 

 7 611829 



7012' 

 7 18 

 7 24 

 7 30 

 7 36 

 7 42 

 7 48 



7 54 



8 

 8 6 

 8 12 

 8 18 

 8 24 

 8 30 

 8 36 



1830 

 1831 

 1832 

 1833 



1834 

 1835 

 1836 



183 



1833 



1839 



1840 



1841 



1842 



1843 



1844 



8042' 

 8 48 



8 54 



9 

 9 6 

 9 12 

 9 18 

 9 24 

 9 30 

 9 36 

 9 42 

 9 48 

 9 54 



10 

 10 6 



