Watermanship Page: 97
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(b) By means of Cassiopeia (W). When the Big
Dipper is not visible, another star group may be used to
identify the North Star. On the opposite side of the
North Star, and at about the same distance from it as
the Big Dipper, is a group of five stars, called Cassiopeia,
which forms the letter W, or M if the group is above the
North Star. The relation between the North Star and
the W is shown in figure 52. This should be memorized.
(2) Behavior of stars. At the North Pole, the North
Star appears directly overhead, and both the Big Dipper
and W are visible and seem to rotate around the North
Star. To one going south from the North Pole toward
the Equator, these stars appear to lose elevation; they
are seen nearer the horizon. The 40th parallel of north
latitude, which passes through Pennsylvania, Spain,
Greece, and Japan, is the most southerly point from
which both the Big Dipper and W are always visible.
South of this parallel only one of these star groups is
visible at a time; so half the time it is identified by the
Big Dipper. (See fig. 52.) And half the time by W.
(See fig. 52.)
(3) Southern Hemisphere. There is a faint star called
Sigma Octantis above the South Pole and 10 from it.
However since it is sometimes difficult to recognize and
use this star, the Southern Cross is usually used to deter-
mine direction. Four bright stars form the cross. It is
identified by its shape and relative brilliance, and by the
two bright pointer stars shown in figure 53. The South-
ern Cross appears to rotate about the South Pole just as
the Big Dipper seems to rotate about the North Pole,
but in the opposite direction. The groups are about
the same distance from their respective poles. To locate
the South Pole, consider the Southern Cross a kite. Ex-
tend its long axis 4Y times in the direction of the tail.
(See fig. 53.) The point in the sky thus fixed is approxi,
mately over the South Pole. Use this point for true
south direction. Under favorable light conditions the
South Pole star may be identified and used. From the
vicinity of the Equator, both the Southern Cross and
the Big Dipper are sometimes visible, sometimes only97
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United States. War Department. Watermanship, book, April 25, 1944; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc96650/m1/103/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.