SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE. 



DISCUSSION 



MAGNETIC AND METEOROLOGICAL OBSERVATIONS 



MADE AT THE GIRAED COLLEGE OBSERVATORY, PHILADELPHIA, 

 IN 1840, 1841, 1842, 1843, 1844, AND 1845. 



PART II. 



INVESTIGATION OF THE SOLAR DIURNAL VARIATION IN THE MAGNETIC DECLINATION AND ITS 



ANNUAL INEQUALITY. 



BY 



A. D. BACHE, LL. D. 



[ACCEPTED FOR PUBLICATION, SEPTEMBER, I860.] 



