This is Volume 1 of the Annals of the Astrophysical Observatory of the Smithsonian Institution. The book is the result of research originally due to the discovery, made in 1881 with the newly invented bolometer, of solar heat in spectral region now known as the lower infra-red spectrum. Presented in the book are tables and charts of the infra-red solar spectrum extending to 5.3 microns and mapping nearly 750 lines, of which most are below 1.1 microns and are nearly all new.
Preface
This book is the result of a research originally due to a discovery, made in the year 1881 with the then newly invented bolometer, in the clear air of an altitude of over 12,000 feet, of solar heat in a then unknown spectral region now called the "lower infra-red spectrum". The bolometer has since been used to explore and to map the region in question, through the long succeeding interval, in the latter part of which it has reached an accuracy and a sensitiveness greater than i could once have hoped for.
This map is now (June 18, 1900), after years of constant work, finally published in the present form; not because this edition is final, but because the long labor must come to some term, and because i desire to see its results published while i may hope to see them made useful.
In my early work i was led to notice not only the change of the infra red absorption spectrum at different hours of the day, but at different seasons of the year, without my observations in the last respect having attained a precision which seemed to justify me in publishing them. Of late, improvements on the early methods seem to be at last bringing more conclusive evidence that there are distinguishable effects in the different seasons of the year upon the absorption of the solar heat by the earth's atmosphere, or perhaps it might be said, evidence that the absorption of the earth's atmosphere is directly associated with the seasonal changes of spring, summer, autumn, and winter.
While we are far from looking forward to foretelling by such means the remoter changes of weather which affect the harvests, or to results of such importance as the power of such a prevision would indicate, still it is hardly too much to say that we appear to begin to move in that direction, and it seems to me that my own early hopes of making the study of the solar energy not simply an interesting scientific pursuit, but one of material usefulness, may one day be justified.. by S. P Langley
The following are the topics covered in this astronomy book.
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Preface
This book is the result of a research originally due to a discovery, made in the year 1881 with the then newly invented bolometer, in the clear air of an altitude of over 12,000 feet, of solar heat in a then unknown spectral region now called the "lower infra-red spectrum". The bolometer has since been used to explore and to map the region in question, through the long succeeding interval, in the latter part of which it has reached an accuracy and a sensitiveness greater than i could once have hoped for.
This map is now (June 18, 1900), after years of constant work, finally published in the present form; not because this edition is final, but because the long labor must come to some term, and because i desire to see its results published while i may hope to see them made useful.
In my early work i was led to notice not only the change of the infra red absorption spectrum at different hours of the day, but at different seasons of the year, without my observations in the last respect having attained a precision which seemed to justify me in publishing them. Of late, improvements on the early methods seem to be at last bringing more conclusive evidence that there are distinguishable effects in the different seasons of the year upon the absorption of the solar heat by the earth's atmosphere, or perhaps it might be said, evidence that the absorption of the earth's atmosphere is directly associated with the seasonal changes of spring, summer, autumn, and winter.
While we are far from looking forward to foretelling by such means the remoter changes of weather which affect the harvests, or to results of such importance as the power of such a prevision would indicate, still it is hardly too much to say that we appear to begin to move in that direction, and it seems to me that my own early hopes of making the study of the solar energy not simply an interesting scientific pursuit, but one of material usefulness, may one day be justified.. by S. P Langley
The following are the topics covered in this astronomy book.
- The absorption lines in the infra-red spectrum of the sun
- Historical account of contributory researches
- Account of the progress of the investigations at the Smithsonian Astrophysical Observatory
- Description of the observatory buildings and the apparatus employed in the research -- adjustments of apparatus
- Methods of procedure in preparing and comparing bolographs
- Limitations of the research-sources of error now existing
- The absorption lines in the infra-red solar spectrum; results of bolographic spectrum analysis in 1897-98
- The variations of absorption in the infra-red solar spectrum
- The dispersion of rock salt and fluorite
- Miscellaneous observations such as The accuracy of the bolometer and Radiation from terrestrial sources
- Construction of a sensitive galvanometer
- The determination of wave-lengths in the infra-red spectrum of rock salt
- The constants for rock salt in Ketteler's dispersion formula
- The minute structure of the absorption band omega
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