4i63 Captain Lefroy's Preliminary liepori on 



land. I have therefore pleasure in communicating to the 

 officers and non-commissioned officers who have interested 

 themselves in the subject, a short account of what has been 

 done, for the sake of the encouragement which the results 

 afford for persevering in the undertaking. 



The printed instructions, dated 11th October 1848, ex- 

 pressed in a few words the objects in view in keeping these 

 registers. They were — 1. To ensure the observation of every 

 aurora which should be visible in Canada, so as to afford a 

 better criterion of the actual frequency of the pheenomenon 

 than can be given by observations at any one station. 2. To 

 supply the means of judging how far variations of the mag- 

 netical elements, shown by the instruments at Toronto during 

 cloudy weather, might be connected with aurora visible else- 

 where. 3. To furnish data for computing the height or di- 

 stance of the luminous region from the earth. 4. Lastly, to 

 throw some light on the question whether or no the same 

 aurora is not sometimes seen under considerably different 

 forms by observers stationed not very far asunder. 



It is not worth while to enter into some of these inquiries 

 until all the materials for comparison are accessible, including 

 the observations made in the United States under the instruc- 

 tions of the Smithsonian Institution, and those published in 

 the Regent's reports. I shall confine myself, therefore, at 

 present principally to the first of them. 



In the year 1848, aurora, or auroral light, was observed at 

 Toronto on 69 nights, although for the last six months of the 

 year no observation was made after midnight. This number 

 is exclusive of five observations of a luminous appearance in 

 the clouds, referred to aurora, but not perfectly tietermined. 

 Observations are to be found at other of our stations on many 

 of the same, and on 57 other nights, exclusive of one doubtful 

 one; making a total of 126 decided, and 6 doubtful appear- 

 ances in Canada*. There are about 46 nights in the year 

 on which it was clouded at all the stations ; if we omit these, 

 the proportion is 10 observations to every 26 nights on which 

 observation is not wholly precluded by the state of the sky, 

 or 39 per cent. 



This proportion is greater than that given by any one sta- 

 tion taken singly. We have — 



At Quebec, ill 1848, 52 obs. to 188 practicable nights— 28 per cent. 



At Montreal, 41 ... 201 ... 20 ... 



At Kingston, 64 ... 218 ... 29 ... 



At Toronto, 69 ... 207 ... 33 ... 



At London, C.W., 33 ... 178 ... 19 ... 



* Including Newfoundland for November and part of December. 



