Then there are maps merely intended to give a good general idea of the appearance of the heavens at different hours and seasons.

Plate I.presents four maps of this sort; but a more complete series of eight maps has been published by Messrs.

Walton and Maberly in an octavo work; and my own 'Constellation-Seasons' give, at the same price, twelve quarto maps (of four of which those in Plate I.are miniatures), showing the appearance of the sky at any hour from month to month, or on any night, at successive intervals of two hours.

But maps intermediate in character to these and to Observatory maps are required by the amateur observer.
Such are the Society's six gnomonic maps, the set of six gnomonic maps in Johnstone's 'Atlas of Astronomy,' and my own set of twelve gnomonic maps.

The Society's maps are a remarkably good set, containing on the scale of a ten-inch globe all the stars in the Catalogue of the Astronomical Society (down to the fifth magnitude).