IT is quite a familiar illustration to represent the distances of the stars in terms of the light-year, but I am not aware that it has been noticed that the same figures which express in years the time light occupies in reaching the earth from a star, will also express in miles the distance of the star upon a scale of the radius vector of the terrestrial orbit to the inch. The illustration appears to me useful, as it gives, perhaps, a more distinct idea of the isolation of the solar system in space than can be otherwise obtained, and does not introduce the question of time into the measurement of distance. Thus if the annual parallax of 61 Cygni is assumed to be 0″.434, which is probably very nearly correct, it will take 7½ (7.464) years for its light to reach the earth, and 7½ (7.499) miles will represent the distance of this star on a scale that gives 1 inch to the distance of the sun from the earth.