The making of three-inch objectives, achromatic
and of short focus, wrought a revolution in telescopes and renewed the
demand for refractors, though prices, as compared with those of the
present day, were very great. But improvement was succeeded by
improvement. Larger and still larger objectives were made, yet
progress was not so rapid as not to justify Grant, in 1852, in
declaring to be a "munificent gift" the presentation, about 1838, to
Greenwhich Observatory, of a six and seven-tenths object glass alone,
and so it was esteemed by Mr. Airy, the astronomer royal. Improvement
is still the order of the day, and, as a result of keen competition,
very excellent telescopes of small aperture can be purchased at
reasonable prices. Great telescopes are enormously expensive, and will
probably be so until they are superseded by some simple invention
which shall be as superior to them as they are to the "mighty"
instruments which, from time to time, caused such sensations in the
days of Galilei, Cassini, Huyghens, Bradley, Dollond, and those who
came after them.
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