should take the direction of his labours from previous workers, but be prepared to diverge from acknowledged rules should he feel justified in doing so from his new experiences. [Illustration: Fig. 18. Refracting-Telescope on a German Equatoreal.] _Working-Lists._—Full advantage should be taken of good observing weather. Sir John Herschel most aptly said that no time occupied in the preparation of working-lists is ill-spent. In our climate the value of this maxim cannot be overrated. If the 100 hours of exceptionally good seeing, available in the course of the year, are to be profitably employed, we must be continually prepared with a scheme of systematic work. The observer should compile lists of objects it is intended to examine, and their places must be marked upon the globe or chart so as to avoid all troublesome references during the actual progress of observation. If he has to consult ephemerides and otherwise withdraw attention from the telescope he loses valuable time: moreover the positions hurriedly assigned in such cases are frequently wrong and entail duplicate references, involving additional waste of time; all this may be avoided by careful preparation beforehand. If he has a series of double or variable stars to observe he must tabulate their places in convenient order so as to facilitate the work. If he intend hunting up nebulæ or telescopic comets he must carefully mark their positions relatively to adjoining stars. In the case of selenographical objects or planetary markings he may equally prepare himself by previous study. Adopting these precautions, objects may be readily identified and the work expedited. When no such preparation is made much confusion and loss of time result. On a cloudy, wet day observers often consider it unnecessary to make such provision and they are taken at a great disadvantage when the sky suddenly clears. A good observer, like a good general, ought to provide, by the proper disposition of his means, against any emergency. In stormy weather valuable observations are often permissible if the observer is prompt, for the definition is occasionally suitable under such circumstances. The most tantalizing weather of all is that experienced during an anti-cyclone in winter. For a week or two the barometer is very steady at a high reading, the air is calm, and the sky is obscured with an impenetrable mass of clouds.