_Limited Means no Obstacle._—There are many observers who, having limited means, are apt to consider themselves practically unable to effect good work. This is a great illusion. There are several branches of astronomy in which the diligent use of a small instrument may be turned to excellent account. Perseverance will often compensate for lack of powerful appliances. Many of the large and expensive telescopes, now becoming so common, are engaged in work which could be as well performed with smaller aperture, and when the manifold advantages of moderate instruments are considered, amateurs may well cease to deplore the apparent insufficiency of their apparatus. It is, however, true that refractors have now attained dimensions and a degree of proficiency never contemplated in former times, and that the modern ingenuity of art has given birth to innumerable devices to facilitate the work of those engaged in observation. In many of our best appointed observatories the arrangements are so very replete with conveniences, and so sedatory in their influences, that the observer has every inducement to fall asleep, though we do not find instances of “nodding” recorded in their annals. Further progress in the same direction leads us to joyfully anticipate the time when, instead of standing out in the frost, we may comfortably make our observations in bed. This will admirably suit all those who, like Bristol people, are reported to sleep with one eye open! But, to be more serious, the work of amateurs is much hindered by lack of means to construct observatories wherein they may conduct researches without suffering from all the rigours of an unfavourable climate. Many of them have, like William Herschel a century ago, to pursue their labours under no canopy but the heavens above, and are exposed to all the trying severity of frost and keen winds, which keep them shivering for hours together, and very much awake! [Illustration: Fig. 17. Cooke and Son’s Educational Telescope.]