IN Mr. Mallock's letter on “Definition, Resolving Power and Accuracy,” published in NATURE of May 27 (vol. 109, p. 678), reference is made to the measurement of star images on eclipse plates, from ...
IN NATURE of May 27, p. 678, Mr. A. Mallock suggests as a quantitative measure of “definition” in an optical instrument “the angular or linear size of the field of view compared with the smallest ...