SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE. 



DISCUSSION 



MAGNETIC AND METEOROLOGICAL OBSERVATIONS 



MADE AT THE GIRARD COLLEGE OBSERVATORY, PHILADELPHIA, 

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



PART III. 



INVESTIGATION OF THE INFLUENCE OF THE MOON ON THE MAGNETIC DECLINATION. 



BY 



A. D. BACHE, LL. D. 



[ACCEPTED FOE PUBLICATION, SEPTEMBER, I860.] 



