Popular Astronomy. A Series of Lectures. By G. B. Airy.
(Mac- millan.)—The Astronomer Royal in this little pocket volume undertakes- to instruct all persons who will really give their minds to the subject in the principles on which -the instruments in an observatory are con- structed, and the principles on which the observations made with these- instruments are treated for deduction of the distances and weights of the bodies of the solar system. But he warns his readers that they will have to take a good deal of trouble, "and perhaps," he adds, "one of the most valuable results to be derived from a truly intellectual study- of astronomy is the habit of keeping up a sustained attention to all the- successive steps of a long series of reasonings." We cordially agree- with him in his appreciation both of the effort and the result.