The Bausch and Lomb Optical Company has reported completion of a special project of nearly two years' duration for the astrophysics laboratory of the Vatican's Observatory. The task involved production of four identical six‐inch prisms, special lenses, and first‐surface mirrors for a spectrograph to be used in determining the composition of stars of both low and high magnitudes. Made from a flint‐type glass, specially selected and highly annealed, the 61‐degree prisms are reportedly accurate in performance to five‐millionths of an inch. Interferometer tests were used to determine the extent of each polishing operation, which was done by hand and limited to 10 minutes so that heat generated by polishing would not damage the prisms. After each operation the prisms were allowed to cool for an hour. The prism spectrograph will be used with a telescope to record the component colors of starlight, from which further information can be gained concerning the physical and chemical make‐up of the stars. The work was undertaken at the request of Rev. Alois Gatterer, Rev. Joseph Junkes, and Rev. Walter J. Miller, director, assistant director, and papal astronomer, respectively, of the Vatican Observatory.

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