_Photography._—Upon this branch of practical astronomy not much will be said in this volume, as it is rather beyond its scope, and possibly also beyond the resources of ordinary amateurs, so far as really valuable work is concerned. A reference must, however, be made to an innovation which has deservedly assumed a very prominent place, and is clearly destined to exert an accelerating influence on the progress of _exact_ astronomy. At present it is impossible to foretell how far it may be employed and extended, but judging from recent developments its applications will be as manifold as they will be valuable. Photographic records possess a great advantage over others, because they are more accurate and therefore more reliable. They are pictures from Nature taken by means free from the bias and error inseparable from mere eye-estimations or hand-drawings. The latter are full of discordances when compared one with another, and can seldom be implicitly trusted; but in the photograph a different state of things prevails. Here we have a faithful portrayal or reproduction of the object impressed by itself upon the plate. Hence it can be depended upon, because there has been no intermediate meddling either with its position or features by what may be termed artistic misrepresentation. True, there may be imperfections in the process; trifling flaws and obstructions will invariably creep in wherever comparatively new and novel work is attempted, but these will but little detract from the value of its results. Photography is obviously a means of discovery as well as a means of accurate record; for nebulæ and faint stars quite invisible to the eye have been distinguished for the first time upon the negatives. Those of our amateurs who intend working in this branch will find it a productive one, and not decaying in interest; but the necessary outfit will be expensive if thoroughly capable instruments are to be employed in the service. [Illustration: LONDON STEREOSCOPIC CO. PHOTOMEZZOTYPE STANMORE OBSERVATORY. OUTSIDE VIEW]