140 Magnetic Observations at Cambridge, United States. 
Force Magnetometer from 151.1 to 153.3. At this time the Aurora 
had begun to fade. 
January 5, 1842. — About 12h. an auroral arch was visible in the 
northeast, at the altitude of 8°, but it soon died away. 
January 7, 1842.— At 16h. 14m. an arch of Aurora, 12° high, was 
seen in the north-northwest. The same arch, with another resting 
on it, at 20° altitude, was visible at 16h. 24m.; at 16h. 34m. the 
upper arch was partly broken; at 16h. 39m. a similar appearance 
was presented in the southeast. In both these arches stars were 
visible, though nowhere else, as it was cloudy. 
January 9, 1842. — At 14h. 45m. a light appeared, shining through 
the clouds in the north. The following readings of the Declination 
were taken, commencing at 15h.:—137, 145, 138, 142, 141.5, 142, 
138, 144, 137, 146, 142, 142.3, 142.1, 145, 138, 144. At Oh. 15m. 
of January 10, the Declination Magnetometer had the same irreg- 
ular vibration; at all these times, the Horizontal-Force Magnet- 
ometer was moving apparently at random, from 139 to 149; the 
attached thermometer standing at 35°. 
January 15, 1842. — During the extra observations of this day a 
feeble Aurora was noticed. A few columns and heaps of light were 
moving slowly from east to west. The Aurora still continued at the 
end of the observations. A diffused arch was visible in the north- 
northeast, whose apex was from 10° to 12° high. From 2h. 50m., 
when the arch was bright, till 3h. 5m., the Declination Magnet- 
ometer was observed, during which time it crept from 134 to 144, 
and then began to vibrate from 144 to 145. 
February 11, 1842.— At 14h. a slight Aurora was observed. 
February 19, 1842. 
At 3h. the Barometer stood at 29.400, and the Ex. Therm. at 53.8 Violent rain, wind S. W. 3. 
40 29.387 53.8 § + OWLS Wis 5. 
410 29 416 be Ms a = 
4-20 29.393 52.3 a ~ as S. W. 3. 
4 30 29.378 52.1 Moderate rain. 
10 12 29.520 40.0 Wane clouds, 1; wind W. 2. 
Feb. 20 
710 30.290 29.0 Clear and calm. 
August 8, 1842,— At 20h. Om. an auroral light was seen in the 
north. 
