SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE. 



175 



DISCUSSION 



lUaNETIC AND METEOROLOGICAL OBSERVATIONS 



MADE AT THE GIRAED COLLEGE OBSERVATORY, PHILADELPHIA, 



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



THIED SECTION, 



COMPEISING PARTS VII, VIII, AND IX. VERTICAL FORCE. 



INVESTIGATION OF THE ELEVEN (OE TEN) YEAR PEEIOD AND OF THE DISTURBANCES OF THE 

 VERTICAL COMPONENT OF THE MAGNETIC FORCE, AND APPENDIX ON THE MAGNETIC 

 EFFECT OF THE AURORA BOREALIS ; WITH AN INVESTIGATION OP THE SOLAR 

 DIURNAL VARIATION, AND OP THE ANNUAL INEQUALITY OF THE VER- 

 TICAL FORCE ; AND OF THE LUNAR EFFECT ON THE VERTICAL 

 FORCE, THE INCLINATION, AND TOTAL FORCE. 



A. D. BACHE, LL.D., F.R.S., 



MEM. CORS. ACAf). SO. PABIS ; PEEST. NAT. ACAD. SCIENCES; SDPERINTENDENT U. S. COAST SUEVET. 



[accepted for PUBLICATION, AUGUST, 1863.] 



