noon
`` By the observations we are able to take with the perfect instruments we possess , we are able at all times to ascertain our exact position on the ocean ; and we might thus sail round either Cape Horn or the Cape of Good Hope to New South Wales without once sighting land till we were about to enter Port Jackson . '' `` It is very wonderful , '' I said . `` What puzzles me is how you can find the longitude . I know you get the latitude by seeing how high the sun is above the horizon at noon , and then with the aid of the nautical almanac you can easily work out the calculation . '' `` With the aid of the chronometer we can as easily ascertain the longitude , though the calculation is a little longer , '' answered Captain Davenport . `` I can explain it to you more easily . The chronometer shows us the exact time at Greenwich .