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PLATE CLXV. A LOW AURORAL ARC. 



From sketches and observations made on June 3, 1903, at noon ; in Winter- 

 quarters Bay, M'Murdo Sound, looking to the N. 



In this sketch is shown the birth of an auroral arc. When first it appeared on 

 the horizon as a glow of pale straw-coloured light, or as a row of upright beams, 

 there may have been no trace of light in the whole heaven other than the stars ; and 

 yet as one watched, imperceptibly the curtains rose, one arc above another, glowing 

 here and fading there, but always up and upwards with lengthening beams, and 

 increasing brightness. The brightness, however, was seldom great in the displays 

 which appeared to us in M'Murdo Sound. 



