kind; they are indexes simply to the mechanism of particular aggregations, and have no definable connection with the mechanism of the whole.  No considerable error may then be involved in treating them, for purposes of calculation, as indifferently directed, and the elicited solar movement may genuinely represent the displacement of our system relative to its more immediate stellar environment.  This is perhaps the utmost to be hoped for until sidereal astronomy has reached another stadium of progress.

Unless, indeed, effect should be given to Clerk Maxwell’s suggestion for deriving the absolute longitude of the solar apex from observations of the eclipses of Jupiter’s satellites (Proc.  Roy.  Soc., vol. xxx., p. 109).  But this is far from likely.  In the first place, the revolutions of the Jovian system cannot be predicted with anything like the required accuracy.  In the second place, there is no certainty that the postulated phenomena have any real existence.  If, however, it be safe to assume that the solar system, cutting its way through space, virtually raises an ethereal counter-current, and if it be further granted that light travels less with than against such a current, then indeed it becomes speculatively possible, through slight alternate accelerations and retardations of eclipses taking place respectively ahead of and in the wake of the sun, to determine his absolute path in space as projected upon the ecliptic.  That is to say, the longitude of the apex could be deduced together with the resolved part of the solar velocity; the latitude of the apex, as well as the component of velocity perpendicular to the plane of the ecliptic, remaining, however, unknown.

The beaten track, meanwhile, has conducted two recent inquirers to results of some interest.  The chief aim of each was the detection of systematic peculiarities in the motions of stellar assemblages after the subtraction from them of their common perspective element.  By varying the materials and method of analysis, Prof.  Lewis Boss, Director of the Albany Observatory, hopes that corresponding variations in the upshot may betray a significant character.  Thus, if stars selected on different principles give notably and consistently different results, the cause of the difference may with some show of reason be supposed to reside in specialties of movement appertaining to the several groups.  Prof.  Boss broke ground in this direction by investigating 284 proper motions, few of which had been similarly employed before (Astr.  Jour., No. 213).  They were all taken from an equatorial zone 4 deg. 20’ in breadth, with a mean declination of +3 deg., observed at Albany for the catalogue of the Astronomische Gesellschaft, and furnished data accordingly for a virtually independent research of a somewhat distinctive kind.  It was carried out to three separate conclusions.  Setting aside five stars with secular movements ranging above 100”, Prof.  Boss divided the 279 left available