SAO Annals, volume I, parts I and II

Cover......................................................  i
Preface....................................................iii
Summary of the work........................................ iv
Table of Contents..........................................  v
Illustrations..............................................vii

INTRODUCTION
Foundation and early annals of the astrophysical 
  observatory..............................................  1

PART I
The absorption lines in the infra-red spectrum of the sun..  5

Chapter I.--Historical account of contributory researches..  7
Early investigations.......................................  7
The writer's early work at Allegheny....................... 10
Recent investigations of infra-red spectra by others than
the writer................................................. 19

Chapter II.--The present research.......................... 22
Account of the progress of the investigations at the
  Smithsonian Astrophysical Observatory.................... 22
Condition of the research July 1, 1892..................... 23
Progress of the research in the year ending July 1, 1893... 27
Progress of the research in the year ending July 1, 1894... 30
Progress of the research in the year ending July 1, 1895... 35
Progress of the research in the year ending July 1, 1896... 38
Progress of the research in the year ending July 1, 1897... 39

Chapter III.--Description of the observatory buildings and 
  the apparatus employed in the research -- adjustments of 
  apparatus................................................ 40
The observatory............................................ 40
Apparatus.................................................. 43
  Constants of the electrical system....................... 43
  Constants of the optical system.......................... 45
  Siderostat............................................... 45
  Slit..................................................... 46
  Spectrometer and accessories............................. 46
  Bolometer and accessories................................ 47
  Driving clock............................................ 56
  Plate carrier............................................ 58
  Galvanometer and accessories............................. 59
  Battery.................................................. 63
  Comparator............................................... 64
Adjustment of apparatus.................................... 65
  Siderostat............................................... 65
  Slit..................................................... 65
  Mirror system............................................ 65
  Prism.................................................... 66
  Cylindric lens........................................... 67

Chapter IV.--Methods of procedure in preparing and 
  comparing bolographs..................................... 69
The bolographic processes.................................. 69
  1. Preparing the curves.................................. 69
  2. Methods of identification of absorption lines......... 71
Conversion of bolometric curves to linear spectra.......... 73
Comparison and measurement of bolographs to discriminate 
  and fix the position of "real" inflections............... 74

Chapter V.--Limitations of the research-sources of error
  now existing............................................. 76
Limitations of the research................................ 76
  1. Visual resolving power of the prism................... 76
  2. Slit width............................................ 77
  3. Collimation........................................... 77
  4. Bolometric resolution................................. 82
Sources of error........................................... 85
  I.   Optical apparatus................................... 86
  II.  Accidental deflections in record curves.............105
  III. Imperfect mechanism.................................112
  IV.  Preparing linear spectra from bolographs............116
  V.   Comparator measurements.............................118
  VI.  Inherent in the bolographic method..................119
Summary of results of limitations and errors...............122
  A. Limitations...........................................122
  B. Errors................................................123

Chapter VI.--The absorption lines in the infra-red solar
  spectrum; results of bolographic spectrum analysis in 
  1897-98..................................................126
Illustrations..............................................127
Comparison of bolographs...................................129
Notes accompanying bolographs..............................133
Measurements on bolographs.................................137
Reduction of observations..................................171
Tables of final values.....................................176
Comparison of the results with the solar spectrum maps of 
  Higgs and Abney and with infra-red metallic lines of 
  Snow, Lewis, and others..................................200

Chapter VII.--The variations of absorption in the infra-red
solar spectrum.............................................205
  Typical energy curves....................................206
  Irregular variations of absorption.......................207
  Emission and absorption experiments......................215
  Summary..................................................216

PART II
Subsidiary researches......................................217

Chapter I.--The dispersion of rock salt and fluorite.......218
The relative dispersion of rock salt and fluorite..........218
The dispersion of rock salt................................222
Have all rock-salt prisms the same indices of refraction?..236

Chapter II.--Miscellaneous observations....................238
1. The accuracy of the bolometer...........................238
2. Radiation from terrestrial sources......................240
Supplementary note.........................................242

Chapter III.--Construction of a sensitive galvanometer.....244
Purposes for which it was constructed......................244
Considerations governing the construction..................245
Best construction of coils.................................248
The needle system..........................................251
Summary....................................................252

APPENDIX
The determination of wave-lengths in the infra-red 
  spectrum of rock salt....................................253
The constants for rock salt in Ketteler's dispersion
formula....................................................261
The minute structure of the absorption band omega..........263

Index......................................................265