526 
“From the last column in the foregoing Table, it is clear that there 
is a maximum at the Equinoxes, in March and at the end of September, 
and a minimum at the Solstices, in June and December. The greatest 
variation 1s between March and June, and is equal to 2139. The mean 
yearly decrease between 1856 and 1860 = 0718; but between the in- 
complete year 1855, and 1860, it is 1/-008. 
‘«Three days after your departure from Christiania, I was s going in 
a steamer along the coast to Trondhjem, sent by the University to re- 
present it, as its senior member, at the coronation of the king and queen. 
I made observations of the magnetical intensity and dip in Bergen and 
in Trondhjem on different days. , I shall only communicate the latter, 
with former observations by different observers. 
TRONDHJEM. 
Inclination = 7; Horizontal Intensity = 7. 
| 
| t. Observer. 6. Formula. A. t. Observer. A. Formula. | A. 
1823°70 |Sabine, {74° 43'°05|74° 44’-80| — 1/*75 || 1825°5 |Hansteen, 1°3425 1°3423 |+2 
1825°50 |Hansteen,| — 40'70] — 37/°65! + 37:05 || 1832°59|Hansteen, | 1°3579 1'3586 |—7 
1832°57 |Hansteen,| — 10/75} — 12’°97| — 222 || 1838°47|Boeck, 1°3707 13702 [+5 
1838°51 |Meyer, |73° 57'°31/73° 56’*18 + 1/13 || 1860°59)/Hansteen, | 1-°3992 1°3992 0 
1860°6) |Hansteen,| — 25'°50) — 25’-65, — 07°15 
i = 74° 21-362 — 34005 (¢ — 1830) + 0051509 (¢ — 1830). 
H = 1:3410 + 24:925 (¢ — 1825-0) — 0-24116 (¢ — 1825-0). 
These formule give the following values for the yearly decrease of 
dip and intensity :— 
1825 |. - 3’°915 | +24: 
1830 | —3-°400 | +22: 
1835 | -2°885 | +20: 
1840 | -—2°370 | +17: 
1845 |} —-1°855 |} +415: 
1850 | —1°340 | 412: 
1855 | —0°825 |) +10: 
1860 | -0°310 |; 4+ 8: 
Ooo WT oo 
“The minimum of dip = 73° 25"38, and corresponds to the epoch 
¢ =1862°97. The maximum of intensity = 1:4054, corresponding to the 
year 1876-7. The total and vertical intensity can be calculated from 
the computed results, or from the observed quantities.” 
