In the foregoing remarks we have alluded somewhat indefinitely to high powers; and an enquiring but unastronomical reader may reasonably demand some information upon this point. It might have been instructive to have cited the various details that may be said to come into view with progressive increases of magnification. But this would be an all but impossible task, on account of the varying conditions under which all astronomical observations must necessarily be made. When we come to delicate tests, there are no standards of telescopic power and definition. Assuming the instrument to be of good size and high optical character, there is yet a powerful influant of astronomical definition in the atmosphere and its variable state. Upon two-thirds of the clear nights of a year the finest telescopes cannot be used to their full advantage, because the minute flutterings resulting from the passage of the rays of light through moving strata of air of different densities are magnified just as the image in the telescope is magnified, till all minute details are blurred and confused, and only the grosser features are left visible. And supposing the telescope and atmosphere in good state, there is still an important point, the state of the observer’s eye, to be considered. After all it is the eye that sees, and the best telescopic assistance to an untrained eye is of small avail. The eye is as susceptible of education and development as any other organ; a skilful and acute observer is to a mere casual gazer, what a watchmaker would be to a ploughman, a miniature painter to a whitewasher. This fact is not generally recognized; no man would think of taking in hand an engraver’s burin, and expecting on the instant to use it like an adept, or of going to a smithy and without previous preparation trying to forge a horse-shoe. Yet do folks enter observatories with uneducated eyes, and expect at once to realize all the wonderful things that their minds have pictured to themselves from the perusal of astronomical books. We have over and over again remarked the dissatisfaction which attends the first looks of novices through a powerful telescope. They anticipate immediately beholding wonders, and they are disappointed at finding how little they can see, and how far short the sight falls of what they had expected. Courtesy at times leads them to express wonder and surprise, which it is easy to see is not really felt, but sometimes honesty compels them to give expression to their disappointment. This arises from the simple fact that their eyes are not fit for the work which is for the moment imposed upon them; they know not what to look for, or how to look for it. The first essay at telescopic gazing, like first essays generally, serves but to teach us our incapability.