Appropriations Expended, Results Reached, and Present Condition of the Work of the Astrophysical Observatory (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 Excerpt: ...which are generally selected to represent the best results obtained at different periods, the conditions of the experiment are quite varied. (a) Taken October 2, 1895, shows the best such curve taken in the daytime with the earlier system of galvanometer support when it rested directly on a pile of four square flat stones, separated at the corners by rubber, and themselves resting on the pier. The speed of the plate is 1 cm. in one minute, and the record is very free from small deflections. So excellent a day record was, with this earlier system of galvanometer support, very unusual. (b) Taken November 25, 1895, shows a record taken just after midnight at the same speed and with the same support for the galvanometer. While the light used (a calcium light) was so much less intense than sunlight that the difficulty of reproducing this record acts somewhat in its favor, yet the irregularities are, in the original plate, as in the reproduction, much less than those in (a). (c) Taken January 28, 1896, shows a day record similar to (a), but with the galvanometer supported on the Julius three-wire suspension now used. While not better than (b), it is distinctly better than (a). (d) Taken April 16, 1896, is like (c), except that the inner chamber had been extended to include the galvanometer. The resulting absence of "drift" is noteworthy. All these four records were taken with the galvanometer needle described on page 31, and a time of single swing of three to four seconds. The weight of that needle is 56 nigs. (e) Taken November 14, 1896, was made with the needle in use from July, 1896, to August, 1897, and described on page 61. The weight of this needle is 31 mgs., and the time of single swing was five seconds. This record is in all respects taken unde...