HH. A. Newton on the height of Auroral Arches. 289 
Mable of the observed altitudes and amplitudes of auroral arches, with the computed 
ae heights above the earth's surface. 
a Date, | Altitude, { Amptitade. | Meigitin | Height in | Obsorver. 
‘ ° 
| March 27, 1781 | 664 165 38 53 Stiles. 
Sept, 21,1840 | 10-12 120 52-68 84-109 | Herrick. 
| March 6, 1843 5-8 100 42-83 67-138 “ 
/| April 18, 1845, 8 100 83 133 “ 
pril 27, « 10 90+ 155 250 “ 
ae 8 100 83 133 Bradley. 
Oct, 19,1846) 8-10 80+ | 165-214 | 266-345 “ 
Dec. 9, “ 5 50 281 452 Herrick. 
{May 15,1847| 7-8 80 142-165 228-266 " 
‘| June . 50 2 “ 
Aug. 4, « 4 60 154 248 Bradley. 
ee q 90 98 158 as 
Sept, 29, « 10 70-80 290-214 | 467-345 | Herrick. 
Nov. 95, « 10-15 100 111-183 179-295 “ 
May 18,1848) 7 "5+ | 168-222 | 270-358 « 
ve 23, “ 5-6 70 134-165 215-266 | Bradley. 
March 18,1849} 10-15 100 111-183 | 179-295 | Herrick. 
April 6,1850| 10-12 90 155-193 | 250-310 | Bradley. 
vont 18,1851} 93 120-130 | 154-104 | 248-168 “ 
{March 18, «< — 12 120 68 109 Olmsted. 
_ | Sept, 29, « 8 “ 
Sept. 29,1859 | 10-15 100 111-183 | 179-295 | Herrick. 
March 26, 1860 6+ 90+ 80 129 Bradley. 
March 27, « 90-100 | 155-111 | 250-179 “ 
daly 4 | jo4g 100+ | 111-140 | 179-226 “ 
i t3 5 90+ 2 1 “ 
. q 90+ 98 158 * 
Aug. 14, « 8 100+ 83 133 “ 
Th average height as indicated by the table is 184 miles, or 
lometers he observations were not taken with refer- 
gite to the use here made of them, and the results can there- 
: regarded as only approximately correct. Mr. Bradley 
; nents. It furnishes moreover the means of determining 
Y the magnitude of the auroral cloud, but also the 
‘and height of the streamers which often rise from the 
bed mass of light. 
College, March 18th, 1865. 
