Word: spectrum
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Dates: during 1890-1899
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...spectra of all the brighter stars in this large region. Many thousand plates, covering the entire sky, have been taken in this way at the Cambridge and Arequipa stations of this observatory. As a result, numerous remarkable objects have been discovered. One of the latest is the spectrum of a meteor which has thus been photographed for the first time. Since it is impossible to foresee when the bright meteors will appear, or what path they will follow, a photograph will be obtained only when one happens to cross the field of the telescope. A number of trails of meteors...
...Observatory now possesses an excellent photograph of a meteoric spectrum, the first that is known to have been obtained. The photograph is of considerable importance, for although the composition of the meteorites that have fallen to the earth is well known, this spectrum will determine the condition of shooting-stars and meteorites before the great heat engendered in passing through the atmosphere has had time to consume the more fusible components. The deductions from this meteoric spectrum will be announced in full in the next bulletin of the Observatory...
...great power. It has a voltage of 20,000, or forty times as great as the voltage required to run an electric car. This is probably the most powerful storage battery in the world. Professor Trowbridge employs it in the experiments which he is now conducting to determine the spectrum of hydrogen. It is also used in X-ray experiments, the first use of a storage battery for this purpose...
...relative variation in the position of the spectra of the two moving stars. There is reasonable belief that this method will enable such calculations to be made with a degree of accuracy hitherto unobtainable. The spectra of many obscure stars have been carefully studied, and in some cases, peculiar spectrum lines have been noticed which point to the presence of some unknown elements...
Three methods are used here to ascertain the variability of a star. The first, and most commonly used, by means of its spectrum, was invented here. There is at the Observatory a collection of about 100,000 photographic plates of different parts of the heavens, made during the last eight years at this Observatory and at the branch observatory in Peru. When a star is suspected of variability a photograph of it is taken and compared with others of this collection and by this means a complete history of the star during the last eight years is established...