316 ANNUAL OF SCIENTIFIC DISCOVERT. 



approached, sometimes receded, and sometimes they assumed a new 

 angular position, by one end either maintaining a fixed distance or 

 approaching its neighbor, while at the other end they retired from 

 each other. These objects, some' of which were as large in superficial 

 area as all Europe, and some even as the surface of the whole earth, 

 were found to shoot in thin streams across the spots, bringing them 

 over in well-defined streams or comparative lines, as exhibited on the 

 diagram ; sometimes by crowding in on the edges of the spot they 

 closed it in, and frequently at length thus obliterated it. These 

 objects were of various dimensions, but in length generally were 

 from ninety to one hundred times as long as their breadth at the 

 middle or widest part. 



THE ZODIACAL LIGHT. 



In a paper on the above subject, read before the British Associa- 

 tion, 1862, by Prof. Challis, the phenomena of the zodiacal light, as 

 gathered from observations made both in northern and in southern 

 latitudes, were stated to be as follows : As seen in north latitudes, 

 it appears in the west after the departure of twilight, as a very faint 

 light, stretching along the ecliptic, about ten degrees broad at its 

 base in the horizon, and coming to an apex at an altitude of forty to 

 fifty degrees. It is most perceptible in the west in the months of 

 February and March, at which time its apex is near the Pleiades. 

 Similar appearances are presented in the morning before sunrise in 

 the east, in the months of August and September. The light seen in 

 the autumn lies in the same direction from the sun as that seen in the 

 spring. In the southern hemisphere, the appearances are strictly anal- 

 ogous ; but the times and positions of maximum visibility are the even- 

 ings in autumn in the west and the mornings in spring in the east. The 

 portion best seen in the southern hemisphere lies in the opposite di- 

 rection from the sun to that which is best seen in the northern hemi- 

 sphere. The portion seen and the degree of visibility depend on the 

 inclination to the horizon of the part of the ecliptic along which the 

 light stretches. The greater the inclination, the better it is seen. 

 At the December solstice, opposite portions have been seen in the 

 northern hemisphere, one in the morning, and the other in the even- 

 ing ; and in the southern hemisphere opposite portions have been sim- 

 ilarly seen at the June solstice. At these seasons, the ecliptic is 

 inclined at large and equal angles to the horizon, at equal intervals 

 before sunrise and after sunset. 



Professor Challis attributed the zodiacal light to an effect produced 

 on the luminiferous ether by the sun's rotation round its axis, com- 

 bined with a motion of translation of the solar system through space. 

 Shooting stars were similarly attributed to the effect on the ether pro- 

 duced by the motion of the earth in a cycloidal curve, resulting from 

 the same motion of translation and the proper motion of the earth in 

 its orbit. 



COMPANION TO SIRIUS. 



In 1861, Mr. Safford, of the Cambridge Observatory, announced 

 (see Annual of Scientific Discovery, 1862, p. 388) that the irregular- 

 ities observed in the motion of the bright star Sirius could be legiti- 

 mately accounted for on the hypothesis of its revolution around an 



