OF ARTS AND SCIENCES : SEPTEMBER 8, 1868. 57 



places, and to small and imperfect catalogues of auroras, what I have 

 added to his work may not, perhaps, be superfluous. 



I have taken notice, in my memoir, of the attempts made by Mairan, . 

 Ritter, Hoslin, Quetelet, Wartmann, Boue, Baumhauer, Wolf, A. de 

 la Rive, Fritz, and Littrow to establish relations between the periods 

 of auroral maxima and minima, and those of shooting-stars, meteors, 

 earthquakes, disturbances in the earth's magnetism, or the sun's in- 

 flamed surface, and even the larger nutation-period of the earth's axis, 

 to say nothing of hail-storms, snow-storms, lunar halos, winds, etc. 



Since the first two hundred and forty pages of my Memoir on the 

 Periodicity of the Aurora have been printed, General Lefroy, formerly 

 director of the Magnetic Observatory in Toronto, Canada, has put at 

 my disposal his large accumulation of observations in British America ; 

 also Professor Joseph Henry, Secretary of the Smithsonian Institu- 

 tion, has placed in my hands the unpublished records of meteorology 

 made in various parts of the United States, under the auspices of this 

 institution, in accordance with the comprehensive plan of its accom- 

 plished Secretary. Mr. Charles A. Schott has obtained for me, from 

 the original records in possession of the Smithsonian Institution, the 

 dates of one hundred and eight auroras observed by the late Professor 

 Parker Cleaveland, at Brunswick, Maine. During a recent visit to 

 Leyden, I have been able to consult the manuscript records of Mus- 

 schenbroek. From these I have gathered the observations made in 

 Holland on four hundred and sixty-seven auroras, most of which have 

 never been published before. With these new and rich materials, and 

 others not specified, to which I have had access since my first catalogue 

 was printed, I have been induced to pause in the midst of my discus- 

 sion of the secular periodicity of the aurora, and print supplementary 

 catalogues. I therefore postpone any remarks on this point until the 

 investigation is brought to a conclusion. The sum total of all the inde- 

 pendent auroras contained in all my catalogues amounts to eleven 

 thousand nine hundred and fifty-eight. However, the additional obser- 

 vations contained in the second catalogue, embracing, as they do, but a 

 short period of years, will have less influence upon the question of the 

 secular periodicity of the aurora than upon its yearly march from month 

 to month, at Toronto, Quebec, Newfoundland, etc. ; for which the ob- 

 servations in the first catalogue were limited to a small number of 

 years. 



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