ship or L.A.T.--i.e., the
distance in time the ship is from the sun. Then the difference between G
P S and L P S is G P L, measured by the arc L G, and that is the
difference that the ship, represented by its meridian PL, is from the
Greenwich meridian PG. In other words, that is the ship's longitude for,
as mentioned before, longitude is the distance East or West of Greenwich
that any point is, measured on the arc of the celestial equator. The
longitude is West, for you can see LPG or the arc LG is west of the
meridian PG.

Likewise if P E is the meridian of your ship, the Longitude in time is
the S.H.A. or L.A.T., E P S (the distance your ship is from the sun)
less the G.H.A. or G.A.T., G P S (the distance Greenwich is from the
sun) which is the angle G P E measured by the arc G E. And this
Longitude is East for you can see G P E, measured by G E, is east of the
Greenwich meridian, P G.

In both these cases, however, the longitude is expressed in time, i.e.,
so many hours, minutes and seconds from the Greenwich meridian and we
wish to express this distance in degrees, minutes and seconds of arc.
The earth describes a circle of 360 deg. every 24 hours. Then if you are 1
hour from Greenwich, you are 1/24 of 360 deg. or 15 deg. from Greenwich and if
you are 12 hours from Greenwich, you are 1/2 of 360 deg. or 180 deg. from
Greenwich. By keeping this in mind, you should be able to transpose time
into degrees, minutes and seconds of arc for any fraction of time. It
is, however, all worked out in Table 7 of Bowditch which turn to. (Note
to Instructor: Explain this table carefully). Put in your Note-Book:

89 deg. 24' 26" = (89 deg.) 5h--56m
(24') 1m--36s
(26") 1--44/60s
--------------------
5h--57m--37s 44/60s = 38s

4h--42m--26s
4h--40m = 70 deg.
2m--24s = 36'
2s = 30"
-----------
70 deg. 36' 30"

Also put in your Note-Book this diagram and these formulas: (For diagram
use illustration on p. 40.)

L.M.T. + West Lo. = G.M.T. L.A.T. + West Lo. = G.A.T.
L.M.T. - East Lo. = G.M.T. L.A.T. - East Lo. = G.A.T.

G.M.T. - West Lo. = L.M.T. G.A.T. - West Lo. = L.A.T.
G.M.T. + East Lo. = L.M.T. G.A.T. + East Lo. = L.A.T.

If G.M.T. or G.A.T. is greater than L.M.T. or L.A.T. respectively, Lo.
is West.

If G.M.T. or G.A.T. is less than L.M.T. or