Observations upon Auroral and Optical Phenomena. 219 
not affect the comparison in respect of altitude, except in a trifling 
degree. Indeed, since the motion of the cloud was almost exactly 
along its own rectilinear base, and since the comparison of the ob- 
servations at both stations was made by taking the distance of a fixed 
star (Alpha Draconis) from that base, it being distant only two or 
three degrees at farthest, it may be asserted that any uncertainty 
arising from a difference in the watches of the observers, or their es~ 
timates of the hour and moment, is completely done away by the 
circumstances of the phenomena. 
Under these favorable circumstances, therefore, comparing the 
sketch and notes made on the spot, and at the time of observation, 
by Mr. E. C.. Herrick, at New Haven, at 9h. 15m. P. M. with 
those made under like circumstances by myself at New Britain, and, 
as it happens, at the same moment, I find the distance from Alpha 
Draconis to be the same in both cases,—indicating the entire absence 
of a parallax sufficiently considerable to be detected by this kind of 
observation,—which is of course not expected to be exact,—within 
perhaps 3° or 1°. 
Prof. Stanley had not minuted his observations, at the time of 
making them ; but before having access to any other observations he 
fixed carefully by recollection the situation of the phenomenon at 
9h. 40m. P.M. The cloud thus delineated by him was almost 
identical in extent and situation with the same as delineated by my- 
self, at the last specific observation made by me, at 9h. 30m. at New 
Britain,—except that the distance of the lower line from Alpha Dra- 
conis was in the first case 1° 40’, and in the last 3°—showing a par- 
allax of 1° 20/ only. 
The third observer before alluded to, having also delineated inde- 
pendently on a celestial map the same cloud as observed by him, 
gave it a situation, extent and form, agreeing closely with the obser- 
vations of Prof. Stanley and Mr. Herrick. Not having the map at 
hand J cannot now state particulars, although at the time this obser- 
vation afforded a striking confirmation of the truth of the general 
conclusions we are now about to deduce. 
My object is not, let it be noticed, to show the exact distance and 
height of the cloud observed, but to exhibit proof of this one fact that 
it was elevated, most unquestionably, either above the atmosphere, or 
into its extreme upper regions. By Mr. Herrick’s observations, 
compared with my own, made at, or certainly near, the same mo- 
ment of time, it would appear that the cloud was too distant fora 
