six o'clock
to nine o'clock p.m.
We should then be able to see a passing ship at such a distance as would enable us to attract her attention by means of a flare . Accordingly it was arranged that four of us , namely , Julius , the two stewardesses , and I , should each take one watch in succession . In that latitude , which was only a few degrees north of the Line , day and night were approximately of equal length , and for all practical purposes the night might be reckoned as beginning at six p.m. , and ending at six a.m. Therefore if each of us kept a watch of three hours , we should cover the twelve hours between us . But by this arrangement the same person would keep one particular watch every night , and , of course , the least arduous of the watches would be that from six o'clock to nine o'clock p.m. ; I therefore decided to split this watch into two dog-watches of one and a half hours each , by which arrangement the regularity would be broken , and each of us would get the benefit of the first dog-watch in succession , which seemed to be not only a fair but a desirable thing . To keep a night watch , however , without possessing the means to attract the notice of a passing ship , would be useless . I therefore constructed a sort of framework consisting of four twelve-foot planks , which I set up on edge in the form of a square enclosure on the after extremity of the poop , securing them firmly to the deck planking by means of battens . The planks were nine inches wide , consequently when my work was complete I had a kind of open box twelve feet square and nine inches deep in which to light my flare .