9, 1878.[830] This time it was
stated to have been seen at some distance south-west of the obscured
sun, as a ruddy star with a minute planetary disc; and its simultaneous
detection by two observers--the late Professor James C. Watson,
stationed at Rawlins (Wyoming Territory), and Professor Lewis Swift at
Denver (Colorado)--was at first readily admitted. But their separate
observations could, on a closer examination, by no possibility be
brought into harmony, and, if valid, certainly referred to two distinct
objects, if not to four; each astronomer eventually claiming a pair of
planets. Nor could any one of the four be identified with Lescarbault's
and Leverrier's Vulcan, which, if a substantial body revolving round the
sun, must then have been found on the _east_ side of that luminary.[831]
The most feasible explanation of the puzzle seems to be that Watson and
Swift merely saw each the same two stars in Cancer: haste and excitement
doing the rest.[832] Nevertheless, they strenuously maintained their
opposite conviction.[833]

Intra-Mercurian planets have since been diligently searched for when the
opportunity of a total eclipse offered, especially during the long
obscuration at Caroline Island. Not only did Professor Holden "sweep" in
the solar vicinity, but Palisa and Trouvelot agreed to divide the field
of exploration, and thus make sure of whatever planetary prey there
might be within reach; yet with only negative results. Photographic
explorations during recent eclipses have been equally fruitless. Belief
in the presence of any considerable body or bodies within the orbit of
Mercury is, accordingly, at a low ebb. Yet the existence of the anomaly
in the Mercurian movements indicated by Leverrier has been made only
surer by further research.[834] Its elucidation constitutes one of the
"pending problems" of astronomy.

* * * * *

From the observation at Bologna in 1666-67 of some very faint spots,
Domenico Cassini concluded a rotation or libration of Venus--he was not
sure which--in about twenty-three hours.[835] By Bianchini in 1726 the
period was augmented to twenty-four _days_ eight hours. J. J. Cassini,
however, in 1740, showed that the data collected by both observers were
consistent with rotation in twenty-three hours twenty minutes.[836] So
the matter rested until Schroeter's time. After watching nine years in
vain, he at last, February 28, 1788, perceived the ordinarily unifor