If a telescope has no finder, it will be easy for the student to construct one for himself, and will be a useful exercise in optics. Two convex lenses not very different in size from those shown in fig. 1, and placed as there shown--the distance between them being the sum of the focal lengths of the two glasses--in a small tube of card, wood, or tin, will serve the purpose of a finder for a small telescope. It can be attached by wires to the telescope-tube, and adjusted each night before commencing observation. The adjustment is thus managed:--a low power being applied to the telescope, the tube is turned towards a bright star; this is easily effected with a low power; then the finder is to be fixed, by means of its wires, in such a position that the star shall be in the centre of the field of the finder when also in the centre of the telescope's field. When this has been done, the finder will greatly help the observations of the evening; since with high powers much time would be wasted in bringing an object into the field of view of the telescope without the aid of a finder. Yet more time would be wasted in the case of an object not visible to the naked eye, but whose position with reference to several visible stars is known; since, while it is easy to bring the point required to the centre of the _finder's_ field, in which the guiding stars are visible, it is very difficult to direct the _telescope's_ tube on a point of this sort. A card tube with wire fastenings, such as we have described, may appear a very insignificant contrivance to the regular observer, with his well-mounted equatorial and carefully-adjusted finder. But to the first attempts of the amateur observer it affords no insignificant assistance, as I can aver from my own experience. Without it--a superior finder being wanting--our "half-hours" would soon be wasted away in that most wearisome and annoying of all employments, trying to "pick up" celestial objects.