epoch A, B, C, D, E, F, G, H, and if at another time the order was A, B, C, D, F, E, G, H, symptoms of variability are pointed out. Repeated observations, where the same star is found in different sequences, will decide the question. Thus, for the stars visible to the naked eye, we know exactly the state of the sky in Herschel's day, now nearly a century ago. Any material change cannot escape us. These catalogues have been singularly overlooked by the observers of our generation who have followed this branch of observation, and it was not till 1876 that they received proper attention and a suitable reduction (at the hands of Mr. C. S. Pierce).
We owe to Herschel the first trustworthy account of the stars visible to the naked eye, and since the date of his labors (about 1800) we have similar views published by Argelander (1839), Heis (1848), Argelander and Schönfeld (1857), Gould (1860 and 1872), and Houzeau (1875). Thus his labors have been well followed up.
In the prosecution of this work Herschel found stars whose light was progressively
