Sailing
Method. Divide 1600 by 8 = 200. Every 200 miles you should change your
course 1/4 point East.

_The Chronometer_

The chronometer is nothing more than a very finely regulated clock. With
it we ascertain Greenwich Mean Time, i.e., the mean time at Greenwich
Observatory, England. Just what the words "Greenwich Mean Time" signify,
will be explained in more detail later on. What you should remember here
is that practically every method of finding your exact position at sea
is dependent upon knowing Greenwich Mean Time, and the only way to find
it is by means of the chronometer.

It is essential to keep the chronometer as quiet as possible. For that
reason, when you take an observation you will probably note the time by
your watch. Just before taking the observation, you will compare your
watch with the chronometer to notice the exact difference between the
two. When you take your observation, note the watch time, apply the
difference between the chronometer and watch, and the result will be the
CT.

For instance, suppose the chronometer read 3h 25m 10s, and your watch,
at the same instant, read 1h 10m 5s. C--W would be:

3h -- 25m -- 10s
-- 1 -- 10 -- 05
----------------
2h -- 15m -- 05s

Now suppose you took an observation which, according to your watch, was
at 2h 10m 05s. What would be the corresponding C T? It would be

WT 2h -- 10m -- 05s
C -- W 2 -- 15 -- 05
--------------------
CT 4h -- 25m -- 10s

If the chronometer time is less than the W T add 12 hours to the C T, so
that it will always be the larger and so that the amount to be added to
W T will always be +. For instance, CT 1h--25m--45s, WT 4h--13m--25s,
what is the C-W?

CT 13h--25m--45s
WT 4 --13 --25
----------------
C--W 9h--12m--20s

Now, suppose an observation was taken at 6h 13m 25s according to watch
time. What would be the corresponding CT?

WT 6h--13m--25s
C--W 9 --12 --20
----------------
15h--25m--45s
--12
----------------
CT 3h--25m--45s

Put in your Note-Book: CT = WT + C - W.

If, in finding C-W, C is less than W, add 12 hours to C, subtracting
same after CT is secured.

Example No. 1:

CT 3h--25m--10s
WT 1 --10 --05
----------------
C--W 2h--15m--05s

WT 2h--10m--05s
+ C--W 2 --15 --05
----------------
CT 4h--25m--10s

Example No. 2: