226 Observations upon Auroral and Optical Phenomena. 



sumed also the appearance of an arch, running nearly parallel with 

 the other. It remained stationary, becoming now and then less dis- 

 tinct and again resuming its original brightness. A few faint beams 

 of light radiated from the northwest towards the zenith ; the sky was 

 perfectly free from clouds, but was overspread with a thin veil of 

 light rendering the smaller stars obscure. The weather was cool, 

 with a wind due north. 



In the comparison of ihe foregoing observations with each other, 

 they manifest a consistency extending through every period of the 

 bow's progress and duration. Thus, in the first stages of the bow, 

 and very soon after its formation, Mr. Ellsworth, at Hartford, saw it 

 lying north of the Crown and of Castor, — certainly at nearly the 

 same moment when Mr. Allen, sixteen miles south of him in latitude, 

 saw the same entirely north of Benetnasch, in ihe tail of the Great 

 Bear. There would seem by this to have been a parallax of about 

 half the breadth of the bow, or a little more— say 7°, to a base of 

 sixteen miles. Again, in the middle stages of the bow. Prof. Olm- 

 sted, fifteen minutes before its disappearance, saw it passing through 

 the Northern Crown, in a position certainly not varying widely from 

 that assigned to it in the same constellation, by Mr. Ellsworth, twenty 

 five minutes before the disappearance. The parallax, therefore, due 

 to a base of thirty two miles would seem by this to be equal to the 

 motion of the bow in ten minutes — say 12°. Finally, in the last 

 stages of the bow, Prof. Olmsted saw it vanish when its south mar- 

 gin had just reached Arcturus, while Mr. Allen, sixteen miles north, 

 saw its middle upon Arcturus "just before" the disappearance, — 

 and while Mr. Ellsworth, still sixteen miles farther north, saw the 

 same star in the same position relatively to the bow, " ten minutes" — 

 before the disappearance. The parallax between the stations at 

 New Haven and Hartford, would, by the last comparisons, appear 

 to be something greater than the motion of the bow di^ring the last 

 ten minutes of its appearance, during a part of which ten minutes, 

 according to Prof. Olmsted, it was stationary. The motion was 

 about the same according to each observer — rather exceeding, in the 

 average of all three, one degree to a minute. The breadth of the 

 bow in its middle stages, appears by Prof. Olmsted's observations to 

 have been about 12°. It is impossible, from the foregoing observa- 

 <tions, to fix upon a definite parallax, although we may approximate 

 to it with entire certainty. The observations are perfect in relation 

 to the general object of the present paper — since the largest paral 



