Sir John Franklin then points out that this mass would appear like an arch to a person situated at the horizon by the rules of perspective, assuming its parts to be equidistant from the earth; and mentions a case when an Aurora, which filled the sky at Cumberland House from the northern horizon to the zenith with wreaths and flashes, assumed the shape of arches at some distance to the southward. He then continues:—“But the Aurora does not always make its first appearance as an arch. It sometimes rises from a confused mass of light in the east or west, and crosses the sky towards the opposite point, exhibiting wreaths of beams or coronæ boreales on its way. An arch also, which is pale and uniform at the horizon, passes the zenith without displaying any irregularity or additional brilliancy.” Sir John Franklin then mentions seeing three arches together, very near the northern horizon, one of which exhibited beams and even colours, but the other two were faint and uniform. (See example of a doubled arc Aurora observed at Kyle Akin, Skye, Plate VII.) He also mentions an arch visible to the southward exactly similar to one in the north. It appeared in fifteen minutes, and he suggests it probably had passed the zenith before sunset. The motion of the whole body of the Aurora from the northward to the southward was at angles not more than 20° from the magnetic meridian. The centres of the arches were as often in the magnetic as in the true meridian. A delicate electrometer, suspended 50 feet from the ground, was never perceptibly affected by the Aurora. [Sidenote: Aurora does not often appear until some hours after sunset.] Sir John Franklin further remarks that the Aurora did not often appear immediately after sunset, and that the absence of that luminary for some hours was in general required for the production of a state of atmosphere favourable to the generation of the Aurora. [Sidenote: Aurora seen in daylight.] On one occasion, however (March 8th, 1821), he observed it distinctly previous to the disappearance of daylight; and he subsequently states that on four occasions the coruscations of the Aurora were seen very distinctly before daylight had disappeared. [In the article “Aurora Polaris,” Encyc. Brit. edit. ix., the Transactions of the Royal Irish Academy, 1788, are referred to, where Dr. Usher notices that the Aurora makes the stars flutter in the telescope; and that, having remarked this effect strongly one day at 11 A.M., he examined the sky, and saw an Auroral corona with rays to the horizon. Instances are by no means rare of the principal Aurora-line having been seen in waning sunlight, and in anticipation of an Aurora which afterwards appeared.] [Sidenote: The Rev. James Farquharson’s observations. Auroral arch. Passage across the zenith.]