TABLE OF CONTENTS. 1 



PAOI 

 AI'.TIl'LK I. INTRODUCTION. Pp.16. 



Advertisement ........ iii 



List of Officers of the Smithsonian Institution . . . iz 



ARTICLE II. DISCUSSION OP THE MAGNETIC AND METEOROLOGICAL OBSERVATIONS MADE AT 

 THE GiRARi) COLLEGE OBSERVATORY, PHILADELPHIA, IN 1840, 1841, 1842, 

 1843, 1844, AND 1845. Third Section, comprising Parts VII, VIII, 

 AND IX. VERTICAL FORCE. INVESTIGATION OF THE ELEVEN (OR TEN) 

 YEAR PERIOD AND OP THE DISTURBANCES OP THE VERTICAL COMPONENT OP 

 THE MAGNETIC FORCE, AND APPENDIX ON THE MAGNETIC EPPECT OP THE 

 AURORA BOREALIS; WITH AN INVESTIGATION OP THE SOLAR DIURNAL 

 VARIATION, AND OP THE ANNUAL INEQUALITY OP THE VERTICAL FORCE ; 

 AND OP THE LUNAR EFFECT OP THE VERTICAL FORCE, THE INCLINATION, AND 

 TOTAL FORCE. By A. D. BACHE, LL. D., F. R. S., Mem. Corr. Acad. 

 Sc. Paris; Prest. Nat. Acad. Sciences; Superintendent IT. S. Coast Sur- 

 vey. Pp. 72. (Published May, 1864.) 



ARTICLE III. DISCUSSION OF THE MAGNETIC AND METEOROLOGICAL OBSERVATIONS MADE AT 



THE GlRARD COLLEGE OBSERVATORY, PHILADELPHIA, IN 1840, 1841, 1842, 



1843, 1844, AND 1845. Fourth Section, comprising Parts X, XI, AND 

 XII. DIP AND TOTAL FORCE. ANALYSIS OF THE DISTURBANCES OP THE 

 DIP AND TOTAL FORCE; DISCUSSION OP THE SOLAR DIURNAL VARIATION 

 AND ANNUAL INEQUALITY OF THE DIP AND TOTAL FORCE; AND DISCUSSION 

 OP THE ABSOLUTE DIP, WITH THE FINAL VALUES FOR DECLINATION, DIP 

 AND FORCE BETWEEN 1841 AND 1845. By A. D. BACHE, LL.D., F. R.S., 

 Mem. Corr. Acad. Sc. Paris; Prest. Not. Acad. Sciences; Superintendent 

 U. S. Coast Survey. Pp. 44. (Published January, 1865.) 



ARTICLE IV. ON THE CONSTRUCTION OP A SILVERED GLASS TELESCOPE, FIFTEEN AND A HALF 

 INCHES IN APERTURE, AND ITS USE IN CELESTIAL PHOTOGRAPHY. By 

 HENRY DRAPER, M. D., Professor of Natural Science in the University of 

 New York. Pp. 60. (Published July, 1864.) 

 1. Grinding and Polishing the Mirrors ..... 2 



2. The Telescope Mounting ...... 27 



3. The Clock Movement ....... 38 



4. The Observatory . . . 41 



5. The Photographic Laboratory ..... 46 



6. The Photographic Enlarger . . . . . .51 



1 Bach memoir la separately paged and indexed. 



