Taking his newly-invented bolometer to Mount Whitney in the summer of 1881, Samuel Pierpont Langley investigated what he termed the “lower infra-red spectrum” of the sun. Becoming Secretary of the Smithsonian Institution in 1887, Langley set about establishing an Astrophysical Observatory to further research in this area. This two-prism spectroscope was part of the early equipment of that organization. The “Cambridge Scientific Instrument Company” inscription refers to a firm that was established in 1881, and that became the Cambridge Scientific Instrument Company Ltd. in 1895.
Ref: Annals of the Astrophysical Observatory of the Smithsonian Institution 1 (1900): 32.
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