Should the beginner not be willing or able to face the purchase of even a comparatively humble instrument, his case is by no means desperate, for he will find facilities at hand, such as were not thought of a few years ago, for the construction of his own telescope. Two-inch achromatic object-glasses, with suitable lenses for the making up of the requisite eye-pieces, are to be had for a few shillings, together with cardboard tubes of sizes suitable for fitting up the instrument; and such a volume as Fowler's 'Telescopic Astronomy' gives complete directions for the construction of a glass which is capable of a wonderful amount of work in proportion to its cost. The substitution of metal tubes for the cardboard ones is desirable, as metal will be found to be much more satisfactory if the instrument is to be much used. The observer, however, will not long be satisfied with such tools as these, useful though they may be. The natural history of amateur astronomers may be summed up briefly in the words 'they go from strength to strength.' The possessor of a small telescope naturally and inevitably covets a bigger one; and when the bigger one has been secured it represents only a stage in the search for one bigger still, while along with the desire for increased size goes that for increased optical perfection. No properly constituted amateur will be satisfied until he has got the largest and best instrument that he has money to buy, space to house, and time to use. Let us suppose, then, that the telescope has been acquired, and that it is such an instrument as may very commonly be found in the hands of a beginner--a refractor, say, of 2, 2-1/2, or 3 inches aperture (diameter of object-glass). The question of reflectors will fall to be considered later. Human nature suggests that the first thing to do with it is to unscrew all the screws and take the new acquisition to pieces, so far as possible, in order to examine into its construction. Hence many glasses whose career of usefulness is cut short before it has well begun. 'In most cases,' says Webb, 'a screw-driver is a dangerous tool in inexperienced hands'; and Smyth, in the Prolegomena to his 'Celestial Cycle,' utters words of solemn warning to the 'over-handy gentlemen who, in their feverish anxiety for meddling with and making instruments, are continually tormenting them with screw-drivers, files, and what-not.' Unfortunately, it is not only the screw-driver that is dangerous; the most deadly danger to the most delicate part of the telescope lies in the unarmed but inexperienced hands themselves. You may do more irreparable damage to the object-glass of your telescope in five minutes with your fingers than you are likely to do to the rest of the instrument in a month with a screw-driver. Remember that an object-glass is a work of art, sometimes as costly as, and always much more remarkable than, the finest piece of jewellery. It may be unscrewed, _carefully_, from