THE PLANET VENUS.

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more easily prove deceptive, because the phase of such asatellite (if it existed) would, when seeu from the Earth ,necessarily be the same as that of the plauet, and cause it tolook like a smaller image of the latter.

A curious incident of a somewhat similar effect may be citedin the tiny companion star, which M. Otto Struve, for sometime, believed to belong to the bright star Procyon. ProfessorNewcomb also states, in his “Popular Astronomy” (p. 297), thatone of the eye-pieces of the great Washington telescope shows,under certain circumstances, a beautiful little satellite alongsideof Uranus or Neptune , which, however, disappears when thetelescope is moved. Nevertheless Mr. Webb remarks (in his“ Celestial Objects ”) that it is difficult to apply the explanationof an optical delusion, produced by instrumental effects andsometimes called a telescopic ghost, to Short’s observations in1740, who, by the employment of two different instruments,and four different eye-pieces, took every precaution againsterror.

For our own part, although we can hardly believe that asatellite of Venus has as yet really been seen, we must confessthat it appears difficult to explain how observers of some time^ince should have been able to see, or should have thought thatthey saw, so much more than we can see. We are almosttempted to ask,—Did their telescopes, or did their fancy, deceivethem? It may, however, be well, if further observations, witha view to the possible discovery of a satellite, be made withmodern instruments of the most improved construction, eitherunder the clear skies of Italy or of Algiers , or on some elevatedsite, such as that of the new Lick Observatory in the moun-tainous regions of North America . It will also be quite worththe while to watch carefully with very powerful telescopesduring the transit of December 1882, for the appearance of anyvery minute satellite or satellites of Venus (similar in size tothose of Mars ) upon the disc of the Sun.

found to be caused by sunlight falling upon the sliding-tube of the eye-piece. In the above paper many interesting observations of the planetare recorded, accompanied by some striking drawings of spots and othermarkings and irregularities of its surface.