Observations of the Aurora Borealis, 1850-51. 67 



communicated by Mr. E. C. Herrick^ together with any that 

 were found in the Regent's reports for 1848-49, of which par- 

 ticulars were given, or which occm-red at more than one station 

 on the same evening. Also observations by Mr. Dougald Stewart 

 at Ristigouche, L. C. The few observations at sea at present 

 collected, for most of which we are indebted to Captain Oliver 

 Eldridge, have not yet been included. 



It results from the comparison of the six winter months, 

 October to March inclusive, 1850-51, that aurora was seen be- 

 fore midnight withiu the first circle on 88'5 per cent, of practi- 

 cable nights, in the second circle on 80 per cent., and in the 

 third on only 48'5 per cent., indicating a rapid falling off of the 

 causes producing it at distances exceeding 1600 miles from the 

 magnetic pole. 



It is scarcely necessary to say, that these simple numerical 

 comparisons are but the fii'st fruits of the observations ; such as 

 they are, however, they suggest to the mind a spectacle, which, 

 if true in natui-e, must be of wonderful magnificence. The polar 

 light kindling on each meridian as that of day declines, some- 

 times with the splendour of prismatic colouring over half a hemi- 

 sphere; sometimes contracting its circles and paling its fires, 

 for a period of days or weeks ; and sometimes spreading down- 

 wards over the globe with an intensity of which our highest 

 conceptions are probably most inadequate, since, if the region of 

 the display is as elevated as is usually supposed, about a third 

 of its light must be absorbed by the atmosphere. To pm-sue 

 the subject into all its details would lead me much beyond the 

 lim'its of such a communication as this ; but I am truly anxious 

 to convince any gentleman who may have doubts on the subject, 

 that to keep, in ever so plain a way, a journal of such appear- 

 ances as may occur at his station, will be a most acceptable con- 

 tribution to an inquiry which will owe much of its interest and 

 value to the scale on w^hich it is pui'sued ; and especially to in- 

 duce those to whom I have not the advantage of being personally 

 known, and those resident at the remaining posts in the north- 

 em, middle, and extreme western regions, to swell the list. 



With respect to the influence of these displays upon the 

 movements of the magnetical elements registered by photography 

 at Toronto, I may say that I find the symbols which represent, 

 in the abstract, ' total absence of disturbance,' ' moderate disturb- 

 ance,' 'considerable disturbance,' and so on, against almost every 

 variety of observation, and am not yet prepared to give any 

 settled opinion on the subject. 



1 cannot close this letter without referring to the great value 

 of such observations as the following by Mr. Hardisty ; which, 

 probably, but for this attempt to follow up the phaenomcnon to 

 its fountain-head, would never have been added to the veiy few 



F2 



