four o'clock to six
`` What a rum start for him to sing out , ` dead boy ! ' '' I thought so , too -- afterwards . At Eight Bells , or four o'clock in the ordinary parlance of landsmen , Mr Bitpin was relieved by the first lieutenant , who then came on deck with the rest of the starboard watch to take charge , while the port watch went below at the same time . This hour marked the beginning of the first dog watch , which , it may be here mentioned for the benefit of the uninitiated , only lasts two hours , from four o'clock to six , when the second dog watch , of similar duration , commences and continues until eight o'clock , or `` Eight Bells , '' again . These subdivisions of time are necessary on board ship in order to allow all to share alike the rough with the smooth , and give the officers and men a change at regular intervals from day to night service , and the reverse ; for , if all the watches were of equal length , there could not be any possible variation of the hours during which the hands would be on and off duty respectively , the one section of the crew in such case coming on deck at precisely the same time each day and going below in similar rotation . By the system in vogue , however , of cutting one of the watches into two parts , which is common to the seamen of all countries in the mercantile marine and is not merely limited to the routine of our men-of-war , there is a constant change introduced ; so that , the men who take , say , the first watch to-night , from eight o'clock till midnight , will have the middle watch to-morrow night , and so on in regular sequence until the time comes round again for them to `` return to their old love '' again ! `` Glass-eye , '' as the men called the first lieutenant , I noticed , was a much smarter hand than Mr Bitpin , in spite of his drawly way of speaking and lackadaisical airs below ; and when he was officer of the watch there was no lolling about the deck or any of the talking that went on behind the boats and in odd corners , as was the case while `` old growler '' had charge .