A Hartmann Spectrocomparator device to measure accurate displacement of the star by measuring the relative star motion to the observer. The object is first photographed, then the image is attached to the device measuring the distance.
Keywordstool, tools, device, Hartmann Spectrocommparator, Spectra Distance Measuring, Measuring Star Distance
Encyclopaedia Britannica (11th ed., vol. 18) (New York, NY: The Encyclopaedia Britannica Company, 1910)