152 

 CONTEXTS. 



Page. 



I. Journal of Aurokae : — 



1. Introductory Remarks ... ... ... ... 152 



2. Explanation of Terms employed in the Text 153 



3. The Journal ... ... ... ... ... 155 



II. Summary: — 



1. Frequency in relation to Sun-spot Cycle ... 201 



2. The Annual Variation of Frequency ... ... 201 



3. Auroral Storm Periods ... ... ... ... 202 



4. Diurnal Variation ... ... ... ... 203 



5. Frequency in relation to Geographic Direction 205 



6. Diurnal Frequency and Geographic Direction 



considered Conjointly ... ... ... ... 206 



7. Diurnal Variation in Trend ... ... ... 207 



8. Relation to Lines of Magnetic Force ... ... 209 



9. Relation to Land Topography ... ... ... 210 



10. Relation to Meteorological Conditions ... 210 



11. Colour ... 211 



12. Suggestions ... ... ... ... ... ... 211 



I._ JOURNAL OF AURORAE. 



1. Introductory Remarks. 



All directions mentioned in the text are given as true and 

 not magnetic bearings. The magnetic declination at Cape 

 Hoyds was, approximately, 150° E. The time of the entries 

 is stated in a daily round of twenty-four hours, beginning at 

 midnight and ending with the following midnight. For 

 example, 22.30 refers to 10.30 p.m. of the civil scale. 



The hour entered was that of the hut clock, with neces- 

 sary adjustments made at two periods of the year, on 

 occasions when the clock was ascertained to be considerably 

 in error in relation to local mean time. Unfortunately, those 

 of the party in charge of the "time" were not as painstaking 

 as they should have been, and so this record, though relatively 

 accurate in itself, cannot be relied upon, within several 

 minutes of time at least, for comparison with other stations. 



The trend of bands in the sky was noted as frequently as 

 possible, and the direction stated always the real trend, as 

 if observed in the zenith; not the apparent trend as seen in 

 perspective. In cases more than a few degrees from the 

 actual zenith some experience is necessary to accurately deter- 

 mine such direction. As a rule, no attempt was made to log 

 the trend of arcs of low elevation, on account of uncertainties 

 entailed therein. Arcs extending straight across the zenith 



