L.A.T. respectively, Lo. is
East.

Example:

In longitude 81 deg. 15' W, L.M.T. is April 15d--10h--17m--30s A.M. What is
G.M.T.?

L.M.T. 15d--10h--17m--30s A.M.
--12
------------------
L.M.T. 14d--22h--17m--30s
5 --25 W +
------------------
G.M.T. 15d-- 3h--42m--30s
--------

G.M.T. April 15d-- 3h--42m--30s
L.M.T. April 15d--10h--17m--30s A.M.

In what Lo. is ship?

G.M.T. 15d 3h--42m--30s
L.M.T. 14d 22h--17m--30s
------------------
Lo. in T 5h--25m--00s W

Lo. = 81 deg. 15'W

Assign also for Night Work reading the following articles in Bowditch:
276-278-279-226-228-286-287-288-290-291-294 (omitting everything on page
114.)

THURSDAY LECTURE

SIDEREAL TIME--RIGHT ASCENSION

Our last lecture was devoted to a discussion of sun time. Today we are
going to talk about star time, or, using the more common words, sidereal
time.

Now, just one word of review. You remember that we have learned that
astronomical time is reckoned from noon of one day to noon of the next
and hence the astronomical day corresponds to the 24 hours of a ship's
run. The hours are counted from 0 to 24, so that 10 o'clock in the
morning of October 25th is astronomically October 24th, 22 hours or 22
o'clock of October 24th.

Now Right Ascension is different from both astronomical and civil time.
Right Ascension is practically celestial longitude. For instance, the
position of a place on the earth is fixed by its latitude and longitude;
the position of a heavenly body is fixed by its declination and right
ascension. But Right Ascension is not measured in degrees and minutes
nor is it measured East and West. It is reckoned in hours and minutes
all the way around the sky, eastward from a certain point, through the
approximate 24 hours. The point from which this celestial longitude
begins is not at Greenwich, but the point where the celestial equator
intersects the ecliptic in the spring of the year, i.e., the point where
the sun, coming North in the Spring, crosses the celestial equator. This
point is called the First Point of Aries. You will frequently hear me
speak of a star having, for instance, a Right Ascension of 5h 16m 32s. I
mean by that, that starting at the celestial meridian, i.e., the
meridian passing through the First Point of Aries, it will take