nine o'clock
`` Fiddle faddle with your middles and ends , Rose -- I 've been in London , dear , and know that the sun rises later there than in New York , in the month of December , and that I know by the clock , I tell you . '' `` The reason of which is , '' resumed Mulford , `` because the clocks of each place keep the time of that place . Now , it is different with the chronometers ; they are set in the observatory of Greenwich , and keep the time of Greenwich . This watch chronometer was set there , only six months since ; and this time , as you see , is near nine o'clock , when in truth it is only about four o'clock here , where we are . '' `` I wonder you keep such a watch , Mr. Mulford ! '' `` I keep it , '' returned the mate , smiling , `` because I know it to keep good time . It has the Greenwich time ; and , as your watch has the New York time , by comparing them together , it is quite easy to find the longitude of New York . ''