or Aurora Boreal is and Australis. 343 



but were perfectly steady, except a slight tremulous motion 

 which some of them had near the edges." 



Friday, 19thFeb. 1773, Lat.58°49' S., Long.,91° 2'E., Decl. 

 41° 51' W. " During the night the southern lights were some- 

 times very bright, and the colours much more variegated and 

 lively than on Wednesday night ; their motion too was greater, 

 and the phenomenon upon the whole extremely beautiful." 



Saturday, 20th Feb. 1773, Lat. 58° 55' S., Long. 92° 45' E. 

 Decl. 40° 31' W. "At 9 o'clock P.M. the southern light shot 

 up very brilliantly on the east 'point of the horizon in a single 

 steady pillar with a pale reddish light. Its direction was not 

 exactly towards the zenith, but gradually dechned towards the 

 south, and at a greater height became so much weaker that it 

 disappeared near S.E. at an elevation of 45°." 



[This was probably the segment of an arch, the highest point 

 of which would have fallen between east and south if the arch 

 had been perfect. — Hansteen.'] 



"Saturday, 6th March 1773. Lat. 59° 56' S.Long. 119° I'E. 

 — Seen a southern light." 



Sunday, 7th March 1773. Lat. 59° 44' S. Long. 120° 18' E. 

 — " Seen a northern light." 



" Monday, 15th March 1773. Lat. 58° 52' S. Long. 142° 24' 

 E., Decl. 1° 42' W. The southern lights were at times very 

 brilliant and exceedingly beautiful, their colour being lively 

 and their motion quick and remarkable." 



" Thursday, 18th March, 1773, Lat. 56° 5' S.Long. 150° 10' 

 Decl. 14° 44' E. Soon after 9 o'clock P.M. it was very clear, 

 and the southern lights were extremely brilliant and beautiful, 

 and appeared of a semicircular or rainbow-like, form, the tivo 

 ends of which were nearly in the east and west points of the ho- 

 rizon." 



[Thus in the highest poiut of the meridian. Let it at the 

 same time be remarked that the declination was on the 15th 

 March, 1° 42' W.; the 16th, 0° 27' E., and the 18th and fol- 

 lowing days between 13° and 14° E. Thus in this spot near 

 Van Diemen's Land the magnetic meridian nearly coincides 

 with the geographical. Compare with this, Tab. IV. and VI. 

 of the atlas accompanying my work on Terrestrial Magne- 

 tism. — Hanstee?i.^ 



" This arch on being seen first went a considerable part 

 north of the zenith, but rose by degrees, turning, as it were, 

 on its diameter, and stopjjed, after having passed the zenith, 

 just in the southern horizon. This light was at one time so 

 bright that we could see our shadows on the deck." 



[I think the diflcrent positions of this arch may be ex- 

 plained by fig. 4 ; whereWAO represents the first position of 



tljc 



