Fig. 15. Standard form for plotting the apparent paths of flight. On these diagrams the original coördinates, exemplified by [Figure 14], have been moved to center. In practice the sector boundaries are drawn over the circles in red pencil, as shown by the white lines in [Figure 19], making it possible to count the number of birds falling within each zone. These numbers are then tallied in the columns at the lower right of each hourly diagram.
Table 1.—Continuation of Data in [Figure 12], Showing Time and Readings of Observations on 24-25 April 1948, Progreso, Yucatán
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Time In Out Time In Out
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10:37-10:41 Time out 11:15 8 9:30
10:45 5:30 10 11:16 4 11
6 9 5 9
5:30 10 11:17 5 11:30
10:46 6 8 11:18 5 12
3:30 11 6 11:30
5 12 11:19 5:30 11:30
10:47 3:15 1 11:20 6 10
6 8:30 3 12
5:45 11:45 5 12
5 10 11:21 5:45 11
10:48 6 9:45 5 11
10:50 5:30 11 11:23 5 12
10:51 4 11 11:25 5 10:30
10:52 4 2 6 11
5:30 11 6 12
10:53 5:30 11:30 11:27 6 10
5 11 11:28 6 11:30
10:55 5 12 5:30 12:30
5 11 11:29 6 11:30
10:56 6 10 4 12
10:58 4:30 11:30 6:30 10:30
5:45 11:45 6 11
10:59 6:30 10:30 11:30 3 10
11:00 3:30 12 (2 birds at once)
6:30 11 11:31 5 10:30
(2 birds at once) 5:30 10:30
11:03 6 11 11:32 6 11:30
11:04 3 12 11:33 7:30 9:30
5 12 4 10:30
11:05 6 10 6 11:30
5 11 8 9:30
11:06 6 10:30 11:35 7 10
11:07 3 10 4:30 1
11:08 6 11 11:38 6:30 11
11:10 7 9:30 11:40 5:30 12
11:11 5 9:15 11:42 4 2
11:13 5 12 5 12
11:14 6:30 10 6 10
5:30 1 4 2
4 12 5 12
Table 1.—Concluded
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Time In Out Time In Out
----------------------------- -----------------------------
11:44 8 9:30 8 10:15
7 11 12:16 3:30 1:30
6 10 8 11
11:45 5 12 12:23 7 1:30
6 10:30 6 12:30
5:45 11 12:36 8 11
4 12 12:37 7:30 1
11:46 7 11 12:38 7 12:30
6 12 12:40 8 1
11:47 8 10 12:45 7:30 1
11:48 6 10 12:47 5:30 1
11:49 6:30 10:30 12:48 7 1
11:51 8 10 12:52 5:30 1:30
8 10 12:54-12:55 Time out
8 10 12:56 8 10:45
8 10 12:58 5:30 1:30
6 10 7 1:30
8 10 7 2
6 11 12:59 5 3
7 12 1:00-1:30 Time out
11:52 5 1 1:37 8 12
11:54 7 11 1:38 8 12
6 12:30 1:48 7 1
11:55 5 12 7 1
11:56 7 10 1:51 5:30 11
5 12 1:57 8 1
11:58 8 11 2:07 7 2
11:59 5:30 12 2:09 9 12
12:00-12:03 Time out 2:10 8 1
12:03 5:30 11:30 2:17 9 12
12:04 8 11 2:21 6 2
12:07 6 12:30 2:30 5:30 3:15
7:30 1 2:32 8 2
12:08 5 10:30 2:46 7 1
12:09 5:30 1 3:36 9 2
7:30 2 3:39 8:30 2
12:10 6:30 12:45 3:45 6 4
12:13 8 11 3:55 9 2
12:14 7 1 4:00 8 3
12:15 7 12:30 4:03 9 2
7:15 1:30 4:30 Closed station
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We now have a concise picture of the apparent pathways of all the birds recorded in each hour of observation. But the coördinates do not have the same meaning as readings of a horizontal clock on the earth's surface, placed in relation to the points of the compass. They are merely projections of the birds' courses. An equation is available for reversing the effect of projection and discovering the true directions of flight. This formula, requiring thirty-five separate computations for the pathways reproduced in [Figure 12] alone, is far too-consuming for the handling of large quantities of data. A simpler procedure is to divide the compass into sectors and, with the aid of a reverse equation, to draw in the projected boundaries of these divisions on the circular diagrams of the moon. A standardized set of sectors, each 22½° wide and bounded by points of the compass, has been evolved for this purpose. They are identified as shown in [Figure 16]. The zones north of the east-west line are known as the North, or N, Sectors, as N1, N2, N3, etc. Each zone south of the east-west line bears the same number as the sector opposite, but is distinguished by the designation S.
