A view of the upper deck of 'Alert' (1856) looking aft from behind the main mast
        
        A view of the upper deck of 'Alert' (1856) looking aft from behind the main mast.  The deck was covered with snow to act as insulation with a layer of ash and gravel added.  The blocks are pemmican.  During the first week of May 1876 Nares ordered that the snow was removed from the skylights and bull's-eyes in order to let light in between decks.  The skylight in the foreground has been uncovered.