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 been made within the last two years, by means of photography, at Potsdam, and by eye observations at the Lick Observatory, that the method has been elevated to a precision that entitles its measurements to the respect which has always been accorded to those made by the appliances of the older astronomy.

Professor Vogel at Potsdam photographs a small part of the spectrum of the star in the vicinity of the line G, and for the purpose of comparison introduces with all needful precaution the hydrogen line in that neighbourhood. For certain stars he has recently used some of the lines of iron. The result we must give in Sir W. Huggins' own words. "The perfection of these spectra is shown by the large number of the lines, no fewer than 250 in the case of Capella, within the small region of the spectrum on the plate. Already the motions of about fifty stars have been measured with an accuracy, in the case of the larger number of them, of about an English mile per second."

In a method of such delicacy, involving results of so great interest, it is obviously desirable to have confirmatory measures made under circumstances as widely different as possible. These have been forthcoming from the Lick Observatory in California, thanks to the late Professor Keeler, at that great institution. He has succeeded in obtaining determinations, by direct eye observation with superb instruments, and he has found it possible to execute measurements of a spectrum with an accuracy as great as that obtained by Professor Vogel. The result is so significant that we must again give it in the words of Huggins:

"The marvellous accuracy attainable in Professor Keeler's