Note 25 — Chapter VIII · ACCESSORIES
Reading edition
For full description and method see H. A. Vol. 14, also Miss Furness’ admirable “Introduction to the Study of Variable Stars,” p. 122, et seq. Some modifications are described in H. A. Vol. 23. These direct comparison photometers give results subject to some annoying small corrections, but a vast amount of valuable work has been done with them in the Harvard Photometry.