about two o'clock in the afternoon
He said that this regular alternation of the sea and land breeze in warm latitudes , as in the tropics generally , when the wind blows for so many hours in the day on and off-shore , is owing to the different powers for the radiation and absorption of heat possessed by land and water , so that when the day temperature is highest on the land the alternating breezes will be stronger , and _ vice versa _ . During the day , to illustrate this fact , the radiation of the sun 's heat on the land causes the air to expand and so rise from the surface , which , creating a vacuum , the air from the sea rushes in to fill the void . At night this process is reversed , for , while the surface of the soil will frequently show in the West Indies during the daytime a temperature of a hundred and twenty degrees and more under the meridian sun , the thermometer will sink down in the evening to fifty or sixty degrees ; whereas , the sea , being a bad radiator and its temperature rarely exceeding eighty degrees , even at the hottest period of the day , it is alternately colder and warmer than the land , and the direction of the wind accordingly oscillates between the two . The minimum temperature being at a little before sunrise in the early morning and the maximum somewhere about two o'clock in the afternoon , the change of these breezes usually occurs at some little time after these hours , the one lulling and the other setting in in due rotation -- that is , of course , near the coast , for out in the open sea their effect is not so apparent . In August , which is one of the `` hurricane months '' of the tropics , when the _ Josephine _ left Grenada on her voyage to England , the winds are more variable , blowing at odd and uncertain times ; so , there was every reason for Captain Miles ' taking advantage of the first cat 's - paw of air off the land now , as otherwise , perhaps , he might not have been able to make an offing before morning , when he would lose the advantage of the current amongst the islands towards Saint Vincent , where he had to call in for some puncheons of rum and coffee to complete his cargo . Under the direction of Moggridge , the crew made short work of hoisting in my traps and innumerable boxes , including the cocoa-nuts Doctor Martin had sent down for me , all of which Captain Miles ordered to be taken into the cabin he allotted to me on the starboard side of the ship near his own ; and then , the boat itself was hauled on board by the derrick amidships which had been used for getting in the cargo , there being no davits at the side as in a man-of-war . After seeing this operation satisfactorily accomplished , I went up the poop-ladder and walked aft to the side of Captain Miles , who was now busy about getting the vessel under weigh .