If possible, let the telescope be fixed in the open air. Where money is no object, a few pounds will furnish a convenient little telescope-house, with either a rotating or sliding roof, which enables the instrument to be pointed to any quarter of the heavens. Such houses are now much more easily obtained than they once were, and anyone who has tried both ways can testify how much handier it is to have nothing to do but unlock the little observatory, and find the telescope ready for work, than to have to carry a heavy instrument out into the open. Plate IV. illustrates such a shelter, which has done duty for more than twelve years, covering an 8-1/2-inch With, whose tube and mounting are almost entirely the work of a local smith; and in the _Journal of the British Astronomical Association_, vol. xiv., p. 283, Mr. Edwin Holmes gives a simple description of a small observatory which was put up at a cost of about £3, and has proved efficient and durable. The telescope-house has also the advantage of protecting the observer and his instrument from the wind, so that observation may often be carried on on nights which would be quite too windy for work in the open. [Illustration: PLATE IV. Telescope House and 8-1/2-inch 'with' Reflector.] Should it not be possible to obtain such a luxury, however, undoubtedly the next best is fairly outside. No one who has garden room should ever think of observing from within doors. If the telescope be used at an open window its definition will be impaired by air-currents. The floor of the room will communicate tremors to the instrument, and every movement of the observer will be accompanied by a corresponding movement of the object in the field, with results that are anything but satisfactory. In some cases no other position is available. If this be so, Webb's advice must be followed, the window opened as widely and as long beforehand as possible, and the telescope thrust out as far as is convenient. But these precautions only palliate the evils of indoor observation. The open air is the best, and with a little care in wrapping up the observer need run no risk.