to the Antarctic Begions. 197 



ness through patches of sky of definite forms, which however become 

 visible only in successive portions, as the pulse traverses them, giving 

 the idea of masses of vaporous matter not visible per se, but rendered 

 fitfully so, either by a band of light cast in succession over every part 

 of them from without, or by a temporary phosphorescence developed 

 within their substance when traversed by electric matter. Such 

 pulsations as above described formed very remarkable features of the 

 auroras of October 12, 1833, and of January 18, 1839. 



Any indication of the near viciiiity of auroral phenomena, or of 

 their existence at a level below that of ordinary clouds, should be 

 most minutely investigated at the moment, and carefully and cir- 

 cumstantially recorded. 



On the nights from the 11th to the 14th of November the sky 

 should be watched for the periodical meteors, whose existence seems 

 now to be placed out of doubt ; as also from the 9th to the 13th of 

 August ; and in general any remarkable display of shooting stars 

 should be noted. The zodiacal light also should be observed in 

 clear nights, with a view to the better defining its limits, and ascer- 

 taining if it be really, as some have supposed, variable in its extent 

 or lustre. Remarkable halos, parhelia, and other atmospheric phe- 

 nomena, should be recorded, and careful measures of their dimen- 

 sions taken with sextants or other instruments. 



9. Variable Stars. 



During night-watches in clear weather, in southern regions, many 

 interesting observations might vmdoubtedly be made by any one ac- 

 quainted with the constellations, or provided with a celestial map, 

 as to the comparative lustre and variability of stars. Especially we 

 would point out to the attention of such an observer the stars a Hy- 

 dras et Crateri as certainly, and I Orionis as probably, variable ; the 

 former at its greatest brightness being equal to e Argus, and at its 

 least equal or somewhat inferior to h Argus, which are the best stars 

 for comparison with it. Its period of change, however, being only very 

 imperfectly known, additional observations would be valuable. The 

 remarkable star r} Argus should also be compared with others of the 

 same apparent brightness, or nearly so, with a view to continue the 

 history of its late extraordinary change of lustre. And we would 

 earnestly recommend to any one who may undertake such observa- 

 tions, to form a list of a certain moderate number of stars, graduating 

 from the first magnitude downwards by almost insensible steps, and 

 having rendered himself familiar with them, to note their arrange- 

 ment in order of brightness, — not once only, but on a great many 

 nights, forming on each occasion separate independent judgements; 

 trusting on no account to any printed catalogue, and diligently re- 

 cording and preserving his memoranda. Such observations are not 

 part of the ordinary business of astronomical observations, and are 

 therefore neglected and abandoned to the amateur, the traveller, or 

 the seaman in his night-watches, which they will be found to beguile 



