IN order to prevent any possible misapprehension in connection with your notice (NATURE, vol. xlvi. p. 619) of Mr. Rutherfurd's measures of the stars surrounding β Cygni, may I call attention to the following?—The two stars of Argelander, 27.3435 and 28.334, concerning which a doubt is expressed in my paper, are certainly lacking on the Rutherfurd plates. If they were present they would be very near the edges of the plates, and it is for this reason that I doubted whether we should expect to find them at all. The star numbered 28 in the Rutherfurd list, which appeared only as a sort of elongation of No. 27 on a plate taken at this Observatory, April 19, 1892, is one of the components of Σ2539, as was pointed out by Mr. Burnham in the Astronomical Journal, No. 268, and by myself in the same journal, No. 266.