THE CENTENARY OF THE DISCOVERY OF URANUS. 
215 
old satellites, which constituted tlie main purpose of the observa- 
tions. Some faint objects were occasionally glimpsed near the 
planet, and tbeir relative places determined, but they were 
never found to accompany Uranus. The fact, therefore, that 
no additional satellites were discovered is not to be regarded as 
a strong point in favour of the theory of tbeir non-existence, 
because the great power and excellence of the telescope was 
expressly directed to the attainment of other ends ; and more- 
over the season in which the planet came to opposition was 
distinctly unfavourable for the prosecution of a rigorous search 
for new satellites. There can, however, be no doubt that 
the analogies of the planetary systems interior to Uranus 
plainly suggest that this planet is attended by several satel- 
lites which the power of our greatest telescopes has hitherto 
failed to reveal ; and that it is in this direction, and that of 
Neptune, we may anticipate further discoveries in future years 
when the conditions are more auspicious and the work is entered 
upon with special energy, aided by instruments of even greater 
capacity than those which have already so far conduced to our 
knowledge of the heavenly bodies. 
Notwithstanding the extreme difficulty with which the 
Uranian satellites are observed, the two brighter ones, Titania 
and Oberon , discovered by William Herschel in 1787, have 
been occasionally detected in telescopes of moderate power, and 
identified by means of an ephemeris which has shown that the 
computed positions approximately agree with those observed. 
During the last few years Mr. Marth has published ephe- 
merides of the satellites of both Saturn and Uranus, and 
many amateurs have to acknowledge the valuable aid rendered 
by these tables, which supply a ready means of identifying the 
satellites, and thus act as an incentive to observers who are 
induced to pursue such work for the sake of the interesting 
comparisons to be made afterwards. In one exceptional 
instance the two outer satellites of Uranus appear to have been 
glimpsed with an object-glass of only 4*3 inches aperture, and 
the facts are given in detail in the Monthly Notices of the 
R. A. S., April 1876, pp. 294-6. The observations were made 
in January, February, and March 1876, by Mr. J. W. Ward of 
Belfast ; and the positions of the satellites, as he estimated them 
on several nights, are compared with those computed, the two 
sets presenting tolerably good agreement. Indeed the cor- 
roborations are such as to almost wholly negative any scepticism, 
though such extraordinary feats should always be received 
with caution. In this particular case the chances of being 
misled are manifold ; even Herschel himself fell into error in 
taking minute stars to be satellites and actually calculating 
their periods ; so that when we remember the difficulties of the 
