F. A. P. Barnard on the Zodiacal Light. 219 
This fourth proposition was not perhaps distinctly enunciated 
by Mr. Jones; but as it is sustained, equally with the ot ers, by 
the observations, it is added, in order that the exclusion of ail 
previous hypotheses may be complete ; for if these four proposi- 
tions be admitted, every conjecture which has hitherto been es- 
teemed worthy of a moment’s serious consideration, in regard to 
the source of the zodiacal light, is effectually eut off. No alter- 
hative seems to remain to us but to attribute the appearance to a 
ting surrounding the earth and illuminated by the sun. 
ut though the evidence in favor of this hypothesis is mainly 
negative, the wrjter has no disposition to deny that certain posi- 
tive indications Womnished by the observations seem to point in 
the same direction. 'To such, however, he attaches less import- - 
ance than he might otherwise be disposed to attribute to them, 
for two reasons, viz., 1, they are in themselves so indecisive, that, 
but for the negative evidence, they would have little weight ; 
and, 2, they are of a kind, of which, if the earth has really such 
a ring as is supposed, we ought to have many and conclusive ex- 
amples, instead of occasional and doubtful ones. Upon this 
point it is proposed briefly to dwell, further on. In the mean 
time, a remark or two may be made in regard to the first of the 
foregoing propositions ; in support of which the reasons assigned 
of the zodiacal light ; since nothing can be more uncertain or more 
OU Ww 
design of attaching to them any very high importance 5 
the hypothesis we are considering derives its pl 
