SCIENTIFIC SUMMARY. 
79 
ling in orbits of small eccentricity around the sun ; for in that case the 
luminosity of the gleam would be more constant, and its position more fixed, 
than is actually the case. Nor can the appearance, and changes of appear- 
ance, of the zodiacal light be accounted for by the existence of bodies travel- 
ling in orbits of considerable eccentricity, so long as the whole of each orbit 
lies relatively close by the sun. “We are thus led to the conclusion,” he 
adds, “ that the bodies composing the zodiacal light travel on orbits of con- 
siderable eccentricity, carrying them far beyond the limits of what may be 
called the zodiacal disc. The constitution of the disc thus becomes variable, 
and that within limits which may be exceedingly wide. They must be so, 
in fact, if all the recorded variations of the zodiacal light are to be accounted 
for. In other words, it is requisite (if the evidence is to be explained) that 
the paths of the materials composing the zodiacal light should be not only for 
the most part very eccentric, but that along those paths the materials should 
not be strewn in such a way that a given portion of any path is at all times 
occupied by a constant or nearly constant quantity of matter.” According 
to this view, the constituents of the zodiacal light resemble very closely — at 
least, as respects distribution along their several paths, and the general 
figure of those paths — the meteoric systems which the earth traverses in the 
course of her motion around the sun. Mr. Proctor then proceeds to show in 
how many respects the results deducible from this theory accord with 
known facts respecting the zodiacal light, meteoric systems, comets, and the 
corona. 
The Colours of Jupiter . — The planet J upiter, which has of late formed so 
interesting a subject of study to astronomers, is now very favourably 
situated for observation — having passed his opposition on December 13. His 
colours are even more striking this year than they were in the winter 
months of 1869-70. Mr. Browning thus speaks of the appearance of the 
planet on October 24 and 25, 1870: — “The equatorial belt was of a fuller 
ochreish or tawny colour than when I observed it during the previous op- 
position. A bright belt to the north of the equator was much the brightest 
portion of the planet’s disc. The dark belts on the northern side were of a 
very dark brown, with less copper colour in them than I found during my 
previous observations. The portion of the disc to the south of the equator 
was peculiarly free from belts. This refers specially to the views I obtained 
on the 24th. The hemisphere seen on the 25th had a light and a dark belt 
about midway between the south pole and the equator, tolerably prominent. 
The ochreish belt was mottled all over the surface with white cloudy mark- 
ings or patches — a distinct line of them, though separated by darker mark- 
ings between, evidently encircled the whole of the planet — a little way to 
the south of the true equator.” 
Photographs of Jupiter . — As some question has been raised by the Green- 
wich observers as to the reality of the changes detected and described by 
Mr. Browning, it is worthy of notice that, besides the abundant evidence 
which was brought forward in proof of Mr. Browning’s views by telescopists 
who have observed the planet as well with refractors as with reflectors, 
photography has supplied a proof of singular force and clearness. Lord 
Lindsay has taken two photographic negatives of Jupiter at Mr. De la Rue’s 
observatory, within a quarter of an hour of the time when Mr. Browning 
