OF THE AURORA BOREALIS. 35 



Europe, from 1716 to 1733, inclusive, the number for each month was as 

 follows : — l 



7. July 2 



8. August 23 



9. September 42 



10. October 57 



11. November 46 



12. December 36 



From a similar table, given by Delisle, of auroras observed at St. Petersburg, 

 from 1726 to 1737, inclusive, we derive the following results: — 



1. January 9 7. July 1 



2. February 20 8. August 16 



9. September 42 



10. October 43 



11. November 24 



12. December 13 



A list, digested from the London Philosophical Transactions, embracing thirty- 

 five years, from 1716 to 1850, inclusive, gives the following numbers : — 



1. January 10 7. July 3 



2. February 12 8. August 8 



3. March " 32 9. September 24 



4. April 15 10. October 45 



5. May 3 11. November 20 



6. June 1 12. December 29 



Remarks. 



1. Combining the three foregoing lists, and averaging the months, in the order 

 of their respective numbers, we obtain the following ratios: — 



1. October 145 



2. March 131 



3. November 90 



4. September 88 



5. December 78 



6. February 77 



2. On comparing these results with those obtained for the recent period from 

 1832 to 1848, we perceive that they agree in some respects, but disagree in others. 

 In both, September stands high on the scale, and June low ; but October, which, 

 in the former period, occupied the first rank, stands fourth in the latter period ; and 

 it is remarkable that, except June, this month was the only one during this period 

 which afforded no example of an exhibition of either the first or second class. 



Mairan, pp. 495 and 497. 



