In the transactions of the Royal Astronomical Society of London, lately published, Mr. Alvan Clark, of Boston, Mass., celebrated for his skill as an astronomical instrument maker, is paid a liigh compliment by the Rev. W. R. Dawes, for his 'astronomical discoveries, especially of new double stars. Regarding one of these, he says, "This star is about as difficult as the closest of the Poulkova catalogue, and though on a fine night visible with the eight-inch object glass I now have in use, it would require the full power of a fifteen-inch refractor to divide it. That it attracted Mr. Clark's attention as a double star, is sufficient to prove that his eye, as well as his telescope, must possess extraordinary power of definition." This was accomplished by Mr. Clark with an object glass whose aperturo is only seVen and three-quarter inches.