Reports on the Observations of the Total Solar Eclipse of Decemeber 22, 1870 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1871 edition. Excerpt: ...was necessary to make a small triangulation. On passing out of the city toward the main-land, about one-eighth of a mile (200 meters) beyond the fortifications, we come to an open circular space perhaps three hundred feet (98 meters) in diameter. From this circular space four roads radiate. That directed N. 820 W. (true) leads to Avola and Noto. Traveling along it for a little more than half a mile (860 meters) we come to a small stream, crossed by a substantial stone bridge of three arches. Continuing in the same direction about seven-eighths of a mile (1,390 meters) further we come to another fine stone bridge, which, in this case, consists of a single arch spanning the Anapus River. The land between these two bridges is low and marshy, and the road is an artificial causeway protected throughout nearly its whole length by a stone wall on its eastern side. This wall rises about three feet above the surface of the road, and its top is covered with heavy coping-stones. On these coping-stones Professor Hall and I measured the base-line which is shown on a scale of 1 to 10,000 in Figure 4. The causeway was not quite straight, which obliged us to measure the base in four sections; the northern terminus, 5, Fig. 4, being directly above the key-stone in the east face of the central arch of the three-arched bridge; and the southern terminus, 6, Fig. 4, being directly above the key-stone in the east face of the arch over the Anapus River. The measurements were made on December 20, with my Chesterman's metallic tape-line, which is too long in the proportion of 100.134 to 100.000. This explains the origin of the column, "Corrected distances," in the following table giving the details of the measurement of the base-line: The following...