THE MOST POWERFUL TELESCOPE IN EXISTENCE. 
393 
was selected, and, after much labour, ground, polished, and 
finished. The remaining portion of the instrument and the 
observatory were pushed on as quickly as possible. On August 
1, 1879, the instrument was complete, and the grandest and 
most powerful telescope in existence stood finished before its 
maker, designer, and owner. 
An instrument of this large aperture will take a long time to 
thoroughly test, but it has stood triumphantly all the tests which 
have been applied hitherto. It has been tested on the moon, a most 
crucial test in experienced hands, on Jupiter and Saturn, and on 
faint companions to bright stars. In all cases satisfactory 
results have been obtained.* This proves that the telescope must 
be at least of fine quality, and it bids fair to turn out of the 
highest excellence. It has been used to take photographs of the 
moon, with results very satisfactory to those who are experi- 
enced in these matters. There can be no doubt, therefore, of 
its claims to be a success, so that ere long it will take its place 
in the eyes of most astronomers as the greatest optical instru- 
ment in existence, and the credit of having manufactured and 
of possessing the most powerful telescope in existence has now 
passed from America back to England. 
It may be legitimately asked, What will be the future work 
of this grand instrument? Will it be used to increase our 
knowledge of astronomy, or will it be allowed to rest in idle- 
ness, like so many other fine instruments ? It is to be trusted, 
and it may be safely anticipated, that the former will be its fate. 
It will wear out, not rust out. There is much in astronomy 
which this grand telescope can do. It can be used for observ- 
ing the faint and difficultly visible satellites of Mars, Saturn, 
Uranus, and Neptune. Ail these pressingly want observing 
and measuring, and there are few telescopes of sufficient power 
and excellence to do the work wanted. It can be easily done 
with the new one. Then there is the important question to be 
settled, Are there other satellites to those planets than those 
known ? To this telescope will fall the task of searching for a 
third and more distant satellite of Mars, for a fifth satellite to 
Jupiter, for a ninth and tenth satellite to Saturn, for a fifth and 
sixth satellite to Uranus, and perchance half a dozen new moons 
of Neptune. Moreover, there are the extremely interesting pro- 
blems connected with the minor planets. Does Vesta, Juno, or 
Pallas, possess a satellite or satellites ? If so, their discovery 
would be a great thing for astronomy. Astronomers suspect 
that away beyond Neptune there may be still another giant 
planet, still another member of the solar system. If so, it will 
* Lately this telescope has shown the outer satellite of Mars three weeks 
before it was thought possible it could be seen with the great telescope at 
Washington. 
