young Cornell researcher, Coblentz assembled and calibrated his own IR equipment, and extended the range of IR measurements to longer wavelengths than had ever been reached. By 1905 he had acquired hundreds of spectra by tedious point-by-point measurements with a prism instrument of his own construction. These were published in 1905 with large fold-outs charts (not available in the later reprints), and tables of wavelengths at which various materials absorbed IR light. While such a massive spectral compilation itself was something of a tour de force, it is perhaps not the most important part of Coblentz's 1905 book. Instead, that honor probably goes to his generalization that certain molecular groupings, or functional groups in modern parlance, appeared to absorb specific and characteristic IR wavelengths. In time this would allow scientists to use a molecule's IR spectrum as a type of molecular fingerprint. This generalization had been hinted at in earlier work by others, but not with such a large amount of supporting data as Coblentz presented. Today, IR spectra are used in thousands of laboratories around the globe by scientists in many fields. As an aside, Coblentz's early work on molecular spectra was not given the eager reception that hindsight might suggest. The reasons are numerous and have been explored by several authors. Astronomical studies Coblentz had a long interest in astronomical problems. In 1913, he developed thermopile detectors and used them at Lick Observatory to measure IR radiation from 110 stars, and the planets Mars, Venus, and Jupiter. In this work he was assisted by Seth Nicholson, later of the Mt. Wilson Observatory. Extending this work, Coblentz and Carl Lampland, of the Lowell Observatory, measured large differences between the day and night temperatures on Mars, which implied a thin Martian atmosphere. For his applications of IR detectors to astronomy, Coblentz is regarded as the founder of astronomical infrared spectroscopy. In recognition of his astronomical contributions, craters on the moon and Mars were named after him by the International Astronomical Union. Coblentz also made observations of solar eclipses, and published papers describing his work. Other research An inspection of Coblentz's bibliography shows that from about 1930 his research turned more toward measurements involving the ultraviolet (UV) region and away from infrared work. Much of this research had a distinctly bio-medical slant, such as his investigations of ultraviolet therapy (1938) and the production of skin cancer by UV exposure (1948). Although