ASTRONOMICAL SOCIETY OF WALES.—We have received the Journal of this Society for September, and find it contains some useful information for amateurs. Besides current notes and some short contributions from various members, a brief description is given of the conditions under which Mars is now visible. This is accompanied by some illustrations, among which is an excellent map of Mars, by Schiaparelli. We notice in the table given at the end, describing “The Heavens” for October, that the period of the variable star η Aquila is given as two days nine hours; this is evidently incorrect, being the time from a minimum to a maximum. A variable star period is generally reckoned either from minimum to minimum, or from maximum to maximum, and its length in the case of this star is, roughly, seven days four hours.