ASTRONOMICAL SOCIETY OF THE PACIFIC 159 0.19 A at the a-band of oxygen, this being an enlargement of 60 times the original negatives. The relative velocity of Earth and Mars was -|-17.80 km/sec. The preliminary results are: Cal. {Mars) Obs. (Mars and Sky) AX(wV) +0.35 A +0.03 A AX (O) +0.37 A +0.10 A From the formula AA=(1+-) S, the strength of the . ^ atmospheric lines due to Mars relative to the terrestrial lines was 0.09 for water vapor and 0.37 for oxygen. Considerations of length of path,

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... he elevation of the observing station, and the quantity of water vapor and oxygen above Mount Wilson indicate that for equal areas the water vapor above the surface of Mars at the time of observation was of the order of 5 and the oxygen of the order of 15 percent of that normally in the Earth's atmosphere, that is, the oxygen was less than above Mt. Everest. These results are in full confirmation of those obtained by Campbell and Albrecht at Mount Whitney and Mount Hamilton. Abstract If, according to Kapteyn, proper motions in declination on the system of Boss need a correction of the form G cosS, where G is positive, the declination of the apex of solar motion derived from a group of stars having proper motions on the system of Boss will be too large and the more so the smaller the mean secular parallax of the group of stars considered. This is what is actually found, but it need not be interpreted as a variation in systematic motion with distance. The "Z" component of the solar motion and the coefficient G of the